JPS648078B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to metallization of non-metallic surfaces. To metallize non-metallic surfaces, the individual surface is first made catalytic for electroless metal deposition, and then the catalyzed surface is coated without an external power source and with the required thickness of metal, e.g. Cu or
Exposure to an easily manipulated plating bath solution is typically provided for a sufficient time to form a Ni layer. On the metal layer thus obtained, additional metal plating is usually applied by conventional electrolytic plating. Known methods of making plated through holes in printed circuit boards use this metallization concept and variations thereof to metallize the hole walls. Starting with a two-sided copper-coated laminate as the base material, a suitably sized panel with the required pores is first prepared and made catalytic by immersion in a known catalyst solution; Exposure to an electroless plating bath solution that produces a metal deposit without an external power source for a sufficient time to deposit a metal, typically copper, to a thickness of, for example, 0.5 to 2.5 microns. The first conductive metal layer is further plated using conventional electrolytic plating means. The typical catalyst solutions used in the aforementioned process have been used in the industry for many years and have developed to a relatively high degree of stability. This mechanism is used to oxidize appropriate components present in the electroless plating bath by reducing the complexed metal ions to metals, which act as an internal electron source to be used in the plating reactant. Thereby, surfaces treated with the above solutions catalytically promote the generation of electroless metal deposits. Operation of electroless plating solutions requires careful monitoring of the various components and replenishment of consumed materials. Furthermore, the plating solution has a tendency to precipitate indiscriminately, resulting in the formation of metal, eg copper, deposits on the walls and bottom of the tank used when operating the plating bath. As a result, the plating operation is disturbed and it is necessary to remove the plating solution from the tank and to clean the walls and bottom of the tank by an etching operation. Therefore, electroless metal plating is quite expensive and complex, and requires highly trained operations. Despite the above-mentioned essential drawbacks, to date, first metal layers by electroless plating have been used to metallize non-metallic surfaces, including the above-mentioned processes used in the fabrication of printed circuit boards. It was considered essential as part of all processing processes. U.S. Pat. No. 3,099,608 forms a nearly non-conductive film of colloidal or semi-colloidal particles on the walls of pores made in laminates used in making printed circuits, and copperizes the pore walls. describes the use of palladium-tin-chloride colloids for electrolytic plating. However, this process has been found to have significant drawbacks and is impractical for practical use. Palladium-tin-chloride colloidal dispersions have unacceptably very short lifetimes. It can only be used for about 9 days as the dispersion solidifies and is quite expensive due to its high palladium content.
Furthermore, this method deposits significantly more copper on the surface than on the walls of the through hole, which also makes it unacceptable for economical use. The patent describes the use of a "thin, barely visible film of particles" of "semi-colloidal palladium" deposited on the surface to be plated, the fact that the film has "considerable resistance," and " Palladium, which inherently has the properties of both a catalytic metal and a conductive metal, has the potential to simultaneously and combine activation and conductivity functions.'' (Paragraph 4)
(lines 53 to 56), and further states that ``after electrolytic plating is initiated with the conductor, it is clearly activated by the catalytic properties of palladium, and that the electrolytic deposition process is applied directly onto the film of conductive agent particles. It is based on the teaching that ``Continued'' (paragraph 4, lines 62-66). Column 5, lines 2 to 7 states, ``Colloidal palladium deposits in through-holes are extremely weak conductors and, compared to precipitated graphite, are less useful as substrates for electroplating than electrolytically deposited palladium. have to take help from something else in
In other words, the aid of a catalyst must be used during the Metski reaction.'' Such observations by the above patent applicant began in 1959 and continued with the use of graphite for the metallization of non-conducting materials, and for the metallization of plastic parts and the creation of plates with plated through holes (PTH). Although the first application of the "seeding agent-electroless plating method" was carried out in the same era, a process that can actually be used has not yet been developed. Seeding Agents - Very Early Difficulties Associated with Electroless Technology and Its Improvements;
Considering the complex set of operating, control and maintenance characteristics of electroless plating baths compared to the relatively simple electrolytic plating process, it is unlikely that these observations will have any impact as far as technological improvements over the last 20 years are concerned. It is rather surprising that there was no such thing. This is likely because these observations did not give the person skilled in the art any teachings that would enable their use. In the absence of this teaching, this observation could only be reproduced when using this "conductor solution" and the copper pyrophosphate electrolytic plating baths that existed at the time, without acknowledging the importance of the composition of the copper electrolytic plating bath. It is thought that
For example, of the known formulations for the pyrophosphate electroplating baths used at the time of the patent application, the simplest does not produce copper of sufficient quality for printed circuit boards, and more complex types of baths Although it produced sufficient copper quality, the operability of the processing process was poor. Therefore, this observation was considered to have no industrial practical application. Seeding agents - electroless copper, with or without subsequent electrolytic plating, have resulted in acceptance in the industry as merely a means to metallize non-metallic surfaces. Therefore, the teachings in this patent are far from the present invention. The present invention provides a method for directly electrolytically plating a nonmetallic surface using a seeding method that has conventionally been used only as a pretreatment for electroless plating, and a novel method for producing printed circuit boards using the same. With the goal. The method of the present invention is to electrolytically plate a nonmetallic surface in a container containing an electrolytic plating solution containing a metal B to be electroplated in the form of ions, which is equipped with a counter electrode, and the nonmetallic surface is electrically conductive. A plating method in which the connector part is located adjacent to the outside of the non-metallic surface to be electrolytically plated, and the adjacent connector part is used as an electrode (connector electrode) during electrolytic plating. It is characterized by having the following steps. (a) A number of discontinuous metal seats are provided on the non-metallic surface. Here is the US Patent for Metal Seat
No. 3011920, No. 3532518, No. 3672923 and No.
3672938 (Japanese Patent Publication No. 52-44540), etc., is a discontinuous metal seat formed by a so-called seeding agent, and in the present invention, each of these metal seats is made of a metal different from metal B. It is applied to consist of or include A. (b) exposing said non-metallic surface comprising at least a portion of said connector portion to an electrolytic plating bath solution; This solution has a certain electrical conductivity and furthermore, the rate of deposition of metal B on the surface consisting of or formed by the electroplated metal B species is faster than that of It contains at least one component C, without the pyrophosphate anion, which allows the deposition of metal B on a metal seat containing or consisting of metal A. (c) Pair the connector portion with a potential difference sufficient to (1) initiate electrolytic plating of metal B onto the exposed portion of the connector portion, and (2) permit electrolytic plating of metal B onto adjacent metal seats. Applied between the electrodes. By applying this potential difference, electrolytic plating of metal B starts on the connector portion and the metal seat adjacent thereto, and the connector portion is covered with metal B by electrolytic plating of metal B onto the connector portion. (d) Continue applying the above potential difference until all adjacent metal seats are covered with metal B. the rate of deposition of metal B on the adjacent metal seat is greater than the rate of electrodeposition of metal B onto a surface consisting of or formed by a species of metal B;
This high rate of electrodeposition of metal B onto adjacent metal seats continues until all of the seats are covered with metal B. (e) Continuous electroplating of Metal B on the exposed and electroplated portions of the connector section to form a continuous conductive coating of Metal B having a thickness of at least 0.5 microns. In the present invention, the rate of metal deposition onto the metal sheet is preferably at least one order of magnitude higher than the rate of deposition onto the plated metal, particularly preferably at least two orders of magnitude higher. Further, in the present invention, although not particularly limited, the metal seat and the metal to be plated are metals selected from group b or group of the periodic table of elements, and it is preferable that they are not of the same type. Furthermore, component C used in the present invention is preferably selected from dyes, surfactants, chelating agents, brightening agents or leveling agents. The substrate provided with the metal seat is preferably subjected to one or more treatments selected from heat treatment, treatment using a detergent conditioning agent, and treatment using a reducing agent. The method of the present invention is an improved method for plating non-metallic surfaces on substrates and is highly suitable for plating through-holes in metallized laminates. An advantage of manufacturing printed circuits with plated through holes is the preservation of the copper hole walls. Since copper can be electroplated directly onto the non-metallic pore walls without an electroless metal layer, the physical properties and adhesion of the copper-non-metallic substrate (plastic) interface are greatly improved. This is particularly important for the production of highly reliable printed circuits, such as multilayer circuits. Although the present invention is not bound by any particular theory, it is believed that direct electrolytic plating on nonmetallic surfaces is possible based on the following principle. (1) A metal seat provided on a non-metallic surface is connected to a "connector part" (connector electrode). This connection is provided on the surface by the electrolyte of the plating bath, forming a "resistive path" between the connector section and the adjacent metal seat. A similar electrical path is also formed between the metal seats. (2) In a theoretical electrolyte with infinite electrical conductivity, the higher the electrical conductivity of the electrolyte, the lower the resistance of the "resistive circuit", and all metal seats will have the same potential difference as the connector part. However, on the contrary, with a theoretical electrolyte of very low electrical conductivity, the resistance between the metal seat and the connector part is insufficient to provide a potential difference for plating the metal seat for all practical purposes. seems to be too expensive. (3) In a real electrolyte, a voltage drop appears in the resistive circuit. Therefore, (a) the potential difference supplied by the power supply with respect to the counter electrode and the connector part is not only due to the voltage drop across the electrodes, including the deposition overpotential, but also due to the resistance formed by the electrolyte. An appropriate plating potential difference must be selected to supply the metal seat, also compensating for voltage drops in the conductive conductors. (b) The higher the electrolyte electrical conductivity, the faster the plating rate on the metal sheet and the more uniform its thickness. (c) The electrical conductivity of the electrolyte must be selected to be acceptably high with respect to the Metski factor. The term electrical conductivity, as used here, is defined as a function of the concentration of the species-carrying current, and in acidic baths it is assumed that hydrogen ions act as the main species-carrying current. (1) For all practical purposes, the deposit formed by electrolytic plating is substantially uniform and its thickness is not substantially a function of distance to the connector portion. In the case of printed circuit boards with holes with metallized walls, there must be essentially no unacceptable difference in the thickness of the deposit on the surface and on the hole walls. (2) To overcome the non-uniformity problem also commonly associated with electrolytic plating, certain additives known, for example, as leveling agents, are used in the plating bath. (3) Pyrophosphate electrolytic plating baths containing additives of this type are
It produces satisfactory results when used in the electrolytic plating process. (4) However, currently used copper pyrophosphate baths containing additives of this type reduce the effectiveness of the processing method suggested by the aforementioned US Pat. No. 3,099,608. Generally, the additives used will deposit equally on the finished metal species (copper) and the palladium on the metal seat;
Or, it preferentially adheres to the latter, thereby interfering with or inhibiting the plating operation on the metal seat. Unexpectedly for the above-mentioned patent, we found that the metal species B to be plated adheres itself preferentially, resulting in a plating action on a metal seat of a dissimilar suitable metal A, e.g. palladium. In comparison, the plating action on the surface made of plated metal B is reduced, or it adheres preferentially to the metal A of the metal seat, and the metal A By using a bath composition containing component C, which enhances the plating action on metal sheets consisting of or containing it, satisfactory results are obtained both in uniform thickness and in excellent quality of the deposit. The present invention was completed based on the discovery that the following can be obtained. The present invention overcomes all of the problems identified in the above-mentioned US patent with regard to seeding and electroless-electroplating processes. As is clear from the mechanism theorized above, the applied potential difference can be plated at a faster rate on the plated seat than on the plated out metal. It must be sufficient to electrolytically deposit the metal. One such technique involves measuring the current-potential relationship for the presence or absence of component C versus the location of metal electrodes on various substrates. Potential range applicable to standard electrolytic deposition solutions (e.g., from about 0 to - for copper sulfate and sulfate plating solutions)
At 200 mV versus a saturated carmel electrode, and about -300 to -1000 mV versus a saturated carmel electrode for a copper pyrophosphate plating solution, plating rates on various substrates (e.g., those containing metal seats) will vary depending on whether the plating solution is a component It has been discovered that when C is included, the plating speed is faster compared to other substrates, such as the metal to be plated. The absorbent component of the electrolytic plating solution (component C) comprises the electroplating metal (e.g. copper) electrode and the metal used to form the metal seat (e.g. copper).
It can be selected based on the current-potential difference curve obtained using an electrode made of palladium. Current-potential curves are recorded using a three-electrode system consisting of a test article, a counter, and a reference electrode. Polarization of an electrode can be carried out either by applying a linearly varying potential difference and recording the current (voltage current method) or by applying a constant current and recording the potential difference (potentiostatic method) . The three-electrode system, voltage-current method, and constant-potential method are described in “Modern
Electrochemistry” 891~893 and 1019~
Listed on page 1026. A rapid method of selecting bath compositions for the process of the present invention uses current-potential curves to determine the value of the difference, delta (E) _i, defined below. Delta (E) _i = E′ _i −E″ _i where E′ _i and E″ _i are the potential difference at current density i of the metal used to form the electrolytically plated metal electrode and metal seat, respectively ( 1st
figure). The current density i is in the range of 30-50% of the peak current i _p (FIG. 1). With the current density chosen in this way, the metal electrodes used to form the metal seat are hardly covered by the plating metal at the potential difference E _i . The current density i in the potentiostatic method is also selected in such a way that the metal electrodes used to form the metal seat are hardly coated with the metal to be plated. The absorbent component selection method consists of the following steps. (1) Current for two types of test electrodes, the electrolytically plated metal (e.g. Cu) and the metal used to form the metal seat (e.g. Pb) -
A potential difference (iv) curve is recorded. (2) Select a current density within the range of 30 to 50% of the peak current. (3) Read the potential difference E′ _i and E″ _i for the selected current from the current-potential difference curve (iv). (4) Calculate the difference in potential difference. Delta (E) _i = E′ _i −E″ _i (5) The absorbent component that yields the highest delta (E) _i value is the suitable component, ie the bath with the highest value of differential delta (E) _i is the suitable bath. The same methods and criteria are used to select the appropriate concentration of absorbent component. Other rapid methods for selecting bath compositions for the process of the present invention also use current-potential curves, but
However, in this case the function delta(E)dep is determined and defined as: Delta (E)dep = E′dep − E″dep where _E′dep and E″ _dep are the deposited metal on the electroplated metal substrate and the metal used to form the metal seat, respectively. The potential difference (i.e., the potential difference extrapolated from the current-potential curve to zero current) (FIG. 2). The experimental method is the same technique as the method described above. However, _E'dep and _E''dep are calculated by extrapolating the current-potential curve to zero current and then read the values of _E'dep and _E''dep . In the present method of selecting bath compositions for the process of the present invention, the bath with the highest delta E _dep value is the suitable bath. The absorbent component that produces the highest delta E _dep value is the appropriate concentration of absorbent component. Both of the above rapid methods of selecting bath compositions for galvanostatic plating can be modified for use with other techniques of metal plating, such as pulse plating, galvanostatic or potentiostatic plating. Besides the rapid method described above for selecting the bath composition for the process of the present invention, other methods used in electrochemical academic research (see pages 1017 et seq. of the above-mentioned book) are identical. It can be used in the following ways. Therefore, all components that seek to achieve faster plating speeds on metal seats than on plateable metals as described above are within the scope of this invention. In one embodiment of the invention, component C preferentially attaches itself to the surface of the seeds of metal B compared to the surface of the seeds of metal A, so that the surface formed by the seeds of seat metal A The preferential deposition is made effective by almost suppressing or reducing the plating reaction on the surface formed by metal B while hardly suppressing the plating reaction on the surface. In another embodiment, component C preferentially attaches itself to the seeds of seat metal A, such that the deposited component C reduces the overpotential difference and, as a result, increases the plating relative to the reaction of the surface of the seeds of metal B. Increase reaction. According to a suitable embodiment of the invention, the electrical conductivity of the electrolytic plating bath solution and the potential difference applied to the connector part and the counter electrode are selected to be sufficiently high so that the metal B
A deposition rate is achieved on the surface of the seed of sheet metal A that is at least one order of magnitude higher, and preferably two orders of magnitude higher, than the deposition rate on the surface of the seed of sheet metal A. It has been found that the maximum electrical conductivity suitable for the process of the present invention is as high as is acceptable with respect to other plating factors for all practical purposes. The potential difference applied to the electrodes is also chosen to compensate for the potential drop across the resistive conductor formed by the plating bath solution between the connector portion and the metal seat made of metal A, and between said phosphorescent seats. I also discovered that I had to. Furthermore, it is desirable to choose the potential difference to be the highest value allowed with respect to the other plating factors. Metal A and likewise metal B can be selected from groups b or groups of the Periodic Table of the Elements provided, and both are dissimilar. Suitable metals A and B are selected in such a way that metal A exhibits a lower plating potential difference than metal B under the conditions provided by the plating operation. Suitable metals for A are selected from palladium, platinum, silver and gold, with palladium being most preferred. A suitable metal B is selected from copper and nickel. Suitable electroplating bath solutions are acidic. Component C is a dye, a surfactant, which acts by preferentially adhering itself to the surface made of metal B and reducing or inhibiting the plating reaction.
It can be selected from chelating agents, polishing agents and leveling agents, and alternatively from bipolar agents which preferentially adhere themselves to surfaces made of metal A and increase the plating reaction on said surfaces. Suitable dyes are for example Victoria Pure Blue F80, methylene blue, methyl violet,
Acid Blue 161, Alcian Blue 8GX, and other N-heterocyclic compounds selected from amines, imines, and diazo compounds, including triphenylmethane type dyes and fused ring amines, imines, and diazo compounds. It is something. Suitable surfactants are nonionic surfactants such as alkylphenoxypolyethoxyethanols, such as octylphenoxypolyethoxyethanol, and nonionic fluorocarbon surfaces such as Zonyl FSN from EI Dupont. Contains an activator. Among the many surfactants, including wetting agents and water-soluble organic compounds, proposed for use in electrolytic plating solutions are surfactants and polymers, including polyoxyethylene. Compounds with as few as 4 polyoxyethylene groups and compounds with as many as 1 million have been found to be effective. Preferred groups of such compounds include polymers with as few as 20 polyoxyethylene groups and as many as 150 polyoxyethylene groups. Polyoxyethylene and polyoxypropylene block copolymers containing 10 to 400 oxyethylene groups are also preferred. Among these, preferred block copolymers are those containing 7 to 250 oxyethylene groups. In general, it has been found that these polyoxyethylene compounds, when added to electrolytic plating baths, particularly acidic electroplating baths, will significantly enhance the growth of electrolytic plating metal onto the nonconducting surface that provided the metal seat. There is. These polyoxyethylene compounds are most often used in electrolytic plating solutions in concentrations ranging from 0.1 to 1 g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/g/. The optimum concentration depends on the composition of the electroplating solution and the polyoxyethylene compound chosen. In some cases, concentrations of less than 0.1 or more than 1 g/g and up to 100 g/g may be preferred. Typical chelating agents are riboflavin, 2,4,
Contains 6-(2-pyridyl)-S-triazine and pyrophosphate anions. Suitable polishing and leveling agents include N-heterocyclic compounds, triphenylmethane type dyes, thiourea and thiourea derivatives. Among the thiourea derivatives suitable for use are tetramethylthiuram disulfide and allylthiourea. For example, a suitable commercially available example is Electrochemical's
There is the Electro-Brite PC-667 and Leeronard's Copper Gleam PC. Other suitable additives include saccharin and O-benzaldehyde sulfonic acid derivatives which are particularly useful in Watts' nickel-metal baths. In a suitable embodiment of the invention, each surface is coated with a solution of metal A as a compound or complex, such as a dimetal halide, a metal halide chloride, as exemplified by palladium-tin chloride. A metal seat is formed by processing. Reference examples of the above-mentioned dimetal halides are US Pat. No. 3,011,920; 3,532,518;
can be found in It has been found that to form a metal seat of metal A, it is advantageous to expose the surface to a reducing agent after the above treatment. In the case of seat-forming compounds consisting of tin, it has been found that it is further advantageous to remove the tin compound from the surface on which the seat was provided. This is accomplished with tin-removal solvents that allow the formation of soluble alkali stannites, such as dilute aqueous tetrafluoroboric acid solutions or strongly basic solutions. In order to improve the shelf life of seating-providing surfaces, we have found it advantageous to expose surfaces treated with seating-providing solutions to a thermal processing treatment, e.g. 65-120°C for 10 minutes or longer. did. Surfaces treated as described above immediately after removal from the seating solution will be treated without harmful effects.
It has been discovered that it can be stored for a long period of time, for example 9 months. After long-term storage, it is advantageous to expose the seat to an acidic solution, for example 1 molar sulfuric acid, for 15 to 20 minutes. Suitable reducing agents mentioned above can be selected from sodium borohydride, formaldehyde, dimethylamine borane or hydroxylamine. It has also been found advantageous to pre-treat the non-metallic surface prior to the seating process by exposing it to a detergent conditioning agent, such as an aqueous solution containing a mixture of non-ionic and cationic humectants. The detergent conditioning agents described above are widely used in plating printed circuits and plastic products. The drawings will now be briefly described, although FIGS. 1 and 2 have already been described in detail. Figures 3a to 3f show the state of electrolytic deposition in an electrolytic plating bath, and Figure 3a is a photograph taken 1 minute after electrolytic deposition. The substrate was a copper-clad laminate that provided a palladium metal seat on the walls of the through-hole. The metal being deposited is copper. Figure 3b is a photographic representation of the same substrate captured 2 minutes after electrolytic deposition. Figure 3c is a photographic representation of the same substrate captured 3 minutes after electrolytic deposition. Figure 3d is a photographic representation of the same substrate captured 4 minutes after electrolytic deposition. Figure 3e is a photographic representation of the same substrate captured 5 minutes after electrolytic deposition. Figure 3f is a photographic representation of the same substrate captured 20 minutes after electrolytic deposition. The above series of drawings shows that the metal deposition on the surface of the pores is uniform and continuous. EXAMPLE This example describes the metallization of the walls of a drilled hole in a copper-clad insulating sheet of the type used in printed circuit fabrication. The panels were cut from 1.6 mm thick copper coated FR-4 epoxy glass sheets. Holes were drilled into the copper coated epoxy-glass FR-4 panel. The pore-provided panel is then treated with a solution containing a cationic surfactant, a nonionic surfactant, and an alkanolamine and adjusted to a pH below 4 to clean the pore wall surface for subsequent processing steps. and conditioned. Subsequently, the panel was immersed in a 1% sulfuric acid solution for 5 minutes, rinsed with water, and soaked in a sodium persulfate solution (120
g/PH2 or less) for 45 seconds at 40°C to deoxidize the copper surface, and then rinse again with water. The panels were then treated for 5 minutes in a pre-soaking solution containing 5 g of tin chloride (); 225 g of sodium chloride/and sufficient hydrochloric acid to obtain a pH below 0.5. After the pre-soaking step, the panels were exposed to a palladium-tin-chloride solution for 5 minutes at 55°C. The panels were continuously stirred in the palladium-tin-chloride solution. The palladium-tin-chloride solution was formulated as follows. That is, the solution of Example 3 of U.S. Pat. No. 3,682,671 was combined with 3.5 moles of sodium chloride and 0.08
210 molar by mixing with a solution of tin chloride
Dilute to a palladium concentration of mg/mg. After immersion in the palladium-tin-chloride solution, the panels were rinsed with water, heat treated in an oven at 100° C. for 60 minutes, and then brushed. Several panels were electroplated in an electrolytic plating solution consisting of 0.3 mole copper sulfate; 1.8 mole sulfuric acid; and 1.3 mmol hydrochloric acid. Current density is 3.8A/
(10cm square). Prior to electrolytic plating, the copper surface was deoxidized by immersing it in a sodium persulfate solution for 5 seconds. After 5 minutes of electrolytic plating, the hole walls
Only 10% was covered. After 1 hour of electrolytic plating, the panels were removed and the holes were inspected. The copper was partially electroplated on the hole wall, but no plating was done in the middle, leaving a gap in the center of the hole. Additional panels were electrolytically plated after adding 5g/g of the essential ionic surfactant, octylphenoxy polyethoxyethanol, to the copper plating solution. In less than 5 minutes, the hole walls were completely covered with a continuous film of copper metal without any gaps. EXAMPLE Additional panels prepared by the method of the example were placed in the same copper electroplating solution as in the example, except containing 5 g/ml of methyl violet instead of the nonionic surfactant. I electrolytically plated it. After 5 minutes of electrolytic plating, the hole walls were covered with a completely continuous film of copper metal. EXAMPLE The preparation of the example was repeated except that methyl violet was replaced with methylene blue. Again, after 5 minutes of electrolytic plating, the hole walls were covered with a completely continuous film of copper. EXAMPLE The process of the example was repeated except that the copper electroplating bath was replaced with a Watts nickel electroplating bath. The Watts nickel bath consists of 300 g/ of nickel sulfate; 30 g// of nickel chloride; and 30 g// of boric acid. Only incomplete plating was performed on the hole wall. Watts Satsukaline Polisher
In addition to the nickel bath, and other panels were plated. A completely continuous film of electroplated nickel quickly covered the pore walls. Example: Watts' nickel-metal bath is 20ml/Lectro.
-Nic10-03 (Cellex, O- commercially available from Fusker Chemical & Plastics Company)
The preparation of the example was repeated except that a polishing agent containing benzaldehyde sulfonic acid was included. A completely continuous film of electroplated nickel was obtained on the pore walls. EXAMPLE The procedure of the example was repeated with the exception that Copper Gleam PC (a polish consisting of a triphenylmethane dye used in copper sulfate/sulfuric acid electrolytic plating baths) was added to the Watts nickel bath. A completely continuous film of electroplated nickel was obtained on the pore walls. EXAMPLE This example describes the fabrication of a printed circuit using the metallization techniques of the present invention. Cut FR-4 or CEM-3 grade copper-coated insulating sheets into panels of a size convenient for the manufacturing process. Drill the required holes for the plated through-hole short circuits and deburr the copper surface of the panel. The panels are then treated in cleaning and conditioning solutions, sulfuric acid solution, cleaning, sodium persulfate solution, cleaning, presoaking solution, and palladium-tin-chloride solution, as in the examples. Next, clean the panel and place it in the oven for 20 minutes
Heat treatment at 120°C and brushing.
The panels may be stored at this stage or processed immediately without interrupting the processing process. At this stage, the panel is provided with a plating resist mask created by well-known photoprinting, screen printing or other suitable processing processes. The panel was then placed in an alkaline detergent for 45 seconds at 3A/
(10cm square) and is manufactured using reverse current electrolytic plating method.
Wash and treat with sodium persulfate for 5 seconds (as above) and wash again. The panels were then washed for 5 minutes using a bath consisting of:
Perform electrolytic plating at 3A/(10cm square). Copper sulfate 75 g / Sulfuric acid 190 g / Chloride ions 70 ppm Electro-Brite (PC-667) 5 ml / The resulting panels were then cleaned and copper electrolyzed at 3 A / (10 cm square) for 40 minutes in a bath containing: Metsuki. Copper Sulfate 75g / Sulfuric Acid 190g / Chloride Ion 50ppm Copper Gleam PC 5ml / Alternatively, without going through the two-step electrolytic plating process described above, the panels were heated at 3A/(10cm square) for approximately 45 minutes as described above. Plated in one step during the first electrolytic plating bath. Then wash the panel and then 2A/(10cm
It is converted into a printed circuit board by a well-known solder plating process for 18 minutes (200 sq.
Etch with a copper chloride solution containing ammonia, melt the solder, apply a solder mask, and mill to the dimensions of the circuit board. EXAMPLES Panels are processed in accordance with the Examples up to and including exposing the copper coated panels to a palladium-tin-chloride solution. After this step, it is washed and then immersed in a 5% tetrafluoroboric acid solution, which is a solvent for the tin component of the palladium-tin-chloride seat deposited on the pore walls. The panel is then formulated according to the invention,
Then, it is plated at 3A/(10cm square) in a copper electrolytic plating bath having the following composition. Copper Sulfate 75g / Sulfuric Acid 190g / Chloride Ion 50ppm Copper Gleam PC 5ml / After depositing a 35μ thick copper layer, the panel was cleaned, dried and applied with a positive photoresist etching mask using known techniques. Cover the required circuit diagram, including the through holes to be plated. The copper is etched and the resist is then removed using standard processing steps, resulting in a finished printed circuit board. EXAMPLE This example describes the preparation of a multilayer printed circuit board. A multilayer composite is formed by assembling each layer of circuitry onto an insulating carrier and forming it into a laminate using well-known manufacturing techniques. After making the through holes and removing dirt from the copper layer forming part of the hole walls, the laminate is then processed as described in the Examples and Sections. EXAMPLE This example describes the preparation of a printed circuit board on a neat or uncoated laminate without providing copper foil on the surface. An adhesive layer is provided on the surface of the panel by the method of US Pat. No. 3,625,758 and holes are formed. Attach the panel to electrolytic plating equipment to provide suitable conductive edges to form suitable connector sections. The process of the US patent enhances the adhesion of the panel. The panels are then processed as described in the Examples. EXAMPLE XI A copper coated FR-4 epoxy glass panel is drilled through holes, cleaned and tested using conditioning solution, pre-soak solution and palladium-tin-chloride solution. It was processed as follows. After palladium-tin-chloride solution and washing, the copper coated panels were dried and immersed in each of the following reducing agents (dissolved in a 1.5 molar aqueous sodium hydroxide solution): Sodium Boron Hydroxyl Hydroxylamine Both panels were electroplated for 2 minutes in the copper electroplating bath of the Example. A complete continuous film of copper was obtained on the pore walls. Example XII The procedure of Example XI was repeated, except that the palladium-tin-chloride solution was replaced by an aqueous solution of potassium hexachloroplatinate () and tin chloride (). The reducing agent used was 1 g/g of sodium borohydride. The holes were covered with a continuous film of copper by electrolytic plating in less than 5 minutes. EXAMPLE The preparation of the example was repeated except that the copper sulfate/sulfuric acid bath was replaced with a copper pyrophosphate electroplating bath. The copper pyrophosphate bath had the following formulation. Copper 32g / Pyrophosphate ion 245g / Ammonia 225g / Temperature 52°C Pyrophosphate anion performs the function of component C.
After 5 minutes of plating at 4.5/(10 cm square), the hole walls were completely covered with copper. A conventional polishing agent for copper pyrophosphate plating baths, dimercaptothiadiazole compounds (from M&T Chemical Co.)
Other panels were plated in the same plating bath with the addition of 1 ml of RY61H (commercially available as RY61H). After 5 minutes in a copper pyrophosphate bath using conventional RY61H polish, the pore walls were unplated. Dimercaptothiadiazole is strongly adsorbed onto palladium metal seats and prevents preferential deposition on palladium metal seats. Examples Soak for 0.5 minutes, rinse and then use Pluronic F-127 (BASF-
(commercially available from Wyndt Corporation) and electroplated in accordance with the present invention in the same copper electroplating solution as in the examples except that component C is present in the solution at a concentration of 0.2 g/l. repeated. After electrolytic plating for 5 minutes at a potential difference giving a current density of 3.8 A/dm ² , the pore walls were covered with a completely continuous film of copper. EXAMPLES In the following examples, A was carried out in the same manner as Example XI, and Examples B to O were carried out using various surfactants as component C, with concentrations, current densities and plating times as follows: The method of Example XI was repeated. In all cases, the result after electrolytic plating was a continuous coating of copper covering the pore walls, completely free of defects.

[Table] Pleronic is a trade name of BASF-Wyandt Co., Ltd. for a polyoxyethylene and polyoxypropylene block copolymer.
-127 is a polyoxypropylene base of about 70 oxypropylene units connected to two polyoxyethylene chains containing a total of about 300 oxyethylene groups. In Pluronic F-68, the polyoxypropylene portion contains about 160 units. Pluronik L-42 has about 20 polyoxypropylene units and
It has 15 polyoxyethylene units. Polyox WSR80 is a polyoxyethylene compound with an average molecular weight of 200,000 commercially available from Union Carbide Company. Olin 6G and 10G are alkyl phenyl polyoxyethylene compounds with 6 and 10 oxyethylene groups, respectively. These are commercially available from Orlin. Tergitol Mine Foam-IX is a linear alcohol polyoxypropylene-polyoxyethylene compound commercially available from Union Carbide. EXAMPLE The method of Example XI was repeated except that the electrolytic plating solution was a nickel bath consisting of: 195 g NiSO ₄ 6H ₂ O / 175 g NiCl ₂ 6H ₂ O / 40 g H ₃ BO ₃ / PH 1.5 Temperature 46° C. The non-ionic activator added to this solution as component C was Carbowax 1540 at a concentration of 0.1 g/. After electrolytic plating for 15 minutes at a potential difference of 3.8 A/dm ² , the pore walls were covered with a completely continuous coating of nickel. EXAMPLE To more fully illustrate the effectiveness of polyoxyethylene groups in practicing this invention, anionic activators widely used in the electroplating industry and recommended for use in acidic copper sulfate electroplating baths are presented. Sodium lauryl sulfate was tested as follows. Pluronic F-
1.0 g of sodium lauryl sulfate (commercially available as Duponol C from EI Dupont) was added as a surfactant instead of Pluronic F-127, and Pluronic F- 127 in place of 1.0 g/ammonium polyether sulfate and 1.0 g/ammonium lauryl polyether sulfate (commercially available as Cypon EA from Alcorac)
The method of Example XI was repeated, except that: After a plating time of 5 minutes, the electrolytic plating bath containing polyether sulfate and lauryl polyether sulfate formed a completely continuous film of copper covering the pore walls, whereas the electrolytic plating bath containing lauryl sulfate formed a completely continuous film of copper covering the pore walls. Electrolytic plating did not cover the pore walls even after a plating time of 15 minutes. This experiment shows that lauryl sulfate, a simple linear anionic activator, is ineffective for purposes of the present invention. If a surfactant is selected according to the teachings of the present invention to modify the structure of lauryl sulfate with polyether groups, it becomes effective as component C. EXAMPLE The method of the example was repeated except that substituted thiourea was used in place of Copper Gleam PC. 5 mg of tetramethylthiuram disulfide was used as component C in the first electrolytic plating solution, and 0.8 g of allylthiourea was used in the second solution. After electroplating for 15 minutes at a potential difference of 3.8 amp/sqdm, the hole walls of printed circuit boards plated in both solutions were covered with a continuous coating of copper.

[Brief explanation of the drawing]

Figure 1 is a graph showing the current-potential difference relationship defined by difference delta (E) _i = E′ _i −E″ _i , and Figure 2 is defined by difference delta (E) _dep = E′ _dep −E″ _dep . Graphs showing the current-potential difference relationship, FIGS. 3a to 3f, are a series of explanatory diagrams showing changes over time in electrolytic deposition according to the method of the present invention. A: iv curve for an electrode made of metal 1 (e.g. Pd), B: iv curve for an electrode made of metal 2 (e.g. Cu).

Claims (1)

[Claims] 1. A non-metallic surface is coated in a container equipped with a counter electrode and containing an electrolytic plating solution containing the metal B to be plated selected from group b or group of the periodic table in ionic form. electrolytically plated, the non-metallic surface has a conductive connector part,
A plating method in which the connector portion is located adjacent to the outside of the non-metallic surface to be electrolytically plated, and the adjacent connector portion is used as an electrode during electrolytic plating, comprising: (a) said non-metallic surface; On top, Pd, Pt, Ag and Au
(b) said non-metal comprising at least a portion of said connector portion; the surface has a specified electrical conductivity,
Furthermore, the method further comprises a component (C) that acts so that the deposition rate of metal B is faster on the metal sheet made of or containing metal A than on the electroplated surface made of metal B. (c) applying a potential difference sufficient to initiate electrolytic plating of metal B onto the exposed portion of the connector portion and to permit electrolytic plating of metal B onto adjacent metal seats; and the counter electrode, and the application of this potential difference initiates the electrolytic plating of metal B on the connector portion and the metal seat adjacent thereto, and the electrolytic plating of metal B on the connector portion
(d) continue applying the above potential difference until all adjacent metal seats are covered with metal B; (e) cover the exposed portion of the connector portion and its electroplated surface with metal B; the step of continuously electrolytically plating metal B to form a conductive continuous film of metal B having a thickness of at least 0.5 microns on a portion that has not been previously electrolessly plated. A method of electrolytically plating non-metallic surfaces. 2. A method according to claim 1, characterized in that component C is a dye selected from methylene blue and methyl violet. 3. Component C is a surfactant selected from alkylphenoxy-polyethoxyethanols, nonionic fluorocarbon surfactants, polyoxyethylene compounds, and block copolymers of polyoxyethylene and polyoxypropylene. A method according to claim 1, characterized in: 4. A method according to claim 3, characterized in that component C is selected from compounds containing 4 to 1,000,000 oxyethylene groups. 5. Process according to claim 4, characterized in that component C is selected from compounds containing 20 to 150 oxyethylene groups. 6. Process according to claim 3, characterized in that component C is selected from ethylene oxide-propylene oxide copolymers containing 10 to 400 oxyethylene groups. 7 Component C is 2,4,6-(2-pyridyl)-S-
The method according to claim 1, characterized in that it is a triazine. 8. Component C is a polishing agent and/or leveling agent selected from N-heterocyclic compounds, triphenylmethane dyes, thiourea, allylthiourea, tetrathiuram disulfide, thiourea derivatives, saccharin and O-benzaldehyde sulfonic acid derivatives. The method according to claim 1, characterized in that it comprises a dye. 9. The electrical conductivity of the electrolytic plating bath solution and the potential difference applied between the connector portion and the counter electrode are such that the rate of deposition of site metal A species on the surface is at least one order of magnitude greater than the rate of deposition of metal B species on the surface. 2. A method according to claim 1, characterized in that the speed is sufficiently high to provide a large speed. 10 A potential difference is created between the connector part and the metal seat containing or consisting of metal A, and between adjacent metal seats, so as to compensate for the potential drop on the resistive path formed by the plating bath solution. 10. The method according to claim 9, characterized in that: is adjusted. 11 Under the conditions given to the plating process, metal A
Claim 1, characterized in that the metals A and B are chosen such that the potential difference for the deposition of metal B on top is less negative than the potential difference for the deposition of metal B on metal B itself. The method described in Section 1. 12. The method according to claim 1, characterized in that in the step of forming the metal seat, the metal A in a dissolved state is used as a compound or a complex. 13. The method according to claim 12, wherein the compound is a metal halide or a metal halide double salt. 14 Claim 1, characterized in that the metal halide double salt is palladium-tin-chloride.
The method described in Section 3. 15. The method of claim 12, wherein the solution comprises metal A and a tin halide and the treated surface is then exposed to a tin compound solvent. 16 Treating the nonmetallic surface with a solution containing metal A,
14. A method according to claim 13, characterized in that a plurality of metal seats of metal A are then formed by exposing the surface to heat or a reducing agent. 17. A method according to claim 16, characterized in that the heat treatment is carried out at a temperature of 65 to 120° C. for at least 10 minutes. 18. Process according to claim 16, characterized in that the reducing agent is selected from sodium borohydride, formaldehyde, dimethylamine borane and hydroxylamine. 19 Furthermore, after forming a continuous film of metal B of the desired thickness on the non-metallic surface, the deposition of metal B is terminated and one or more metal layers are electrolytically plated on the film or a portion thereof. A method according to claim 1, characterized in: 20 A metal deposit formed by using at least two types of electrolytic plating bath solutions with different compositions, the first solution containing components that maximize the deposition rate on metal A, and the second electrolytic plating bath solution being formed. 20. A method according to claim 19, characterized in that it is formulated to optimize the properties of. 21. The method according to claim 1, characterized in that the metal B is selected from the group consisting of Cu and Ni. 22 Printing comprising forming holes in a copper-clad insulating sheet or a laminate of such sheets and providing the non-metallic walls of the holes with a metal layer without prior electroless metal plating. A method for manufacturing a circuit board, comprising: (a) electrolytic plating with a predetermined electrical conductivity, comprising a counter electrode and a metal B to be electrolytically plated selected from group b or group of the Periodic Table of the Elements in molten form; A container containing a bath is provided, the copper cladding is positioned adjacent to the outside of the non-metallic surface of the wall to be electrolytically plated, and this adjacent copper cladding is used as an electrode during electrolytic plating. (b) on the wall of said hole, a metal A selected from the group consisting of Pd, Pt, Ag and Au, with the exception of metal B;
(c) in a next step, this copper-clad sheet or laminate is made of copper-clad sheets or laminates having a specified electrical conductivity. , further comprising a component C which acts such that the rate of deposition of metal B is faster on the metal sheet consisting of or containing metal A than on the electroplated surface consisting of metal B. (d) create a potential difference between the copper cladding and the counter electrode sufficient to initiate electrolytic plating of metal B onto the exposed portion of the copper cladding and to permit electrolytic plating of metal B onto adjacent metal seats; By applying this potential difference, electrolytic plating of metal B is started on the copper cladding and the metal seat adjacent to it, and by electrolytic plating of metal B on the copper cladding, the copper clad part is covered with metal B. (e) continuing to apply said potential difference until all of the adjacent metal seats are covered with metal B; and (f) successively electrolytically plating metal B onto said sheets or laminates to at least A method for manufacturing a printed circuit board, comprising the step of forming a conductive continuous film of metal B having a thickness of 0.5 microns. 23 The method further includes the step of providing a negative resist layer on the surface of the copper-clad sheet or laminate, the layer leaving exposed a portion corresponding to the desired conductor pattern including the hole, and the wall forming the metal A. After forming a hole with a seat and creating a continuous film of metal B, one or more metal layers are electrolytically plated on the film, the resist layer is removed, and the areas covered by the resist layer are removed. 23. A method according to claim 22, characterized in that the metal is removed by etching. 24 Further, one or more metal layers are electrically deposited on the film of metal B, and following the electrolytic plating process, a positive resist layer is provided on the surface of the clad sheet or laminate, and the resist layer has no holes. 23. The method of claim 22, further comprising fixing to form a printed circuit board pattern by covering a portion corresponding to a desired circuit pattern and etching away metal not covered by the positive resist layer. Method. 25. A printed circuit in which holes are formed in a non-metal sheet and the non-metal parts of the sheet corresponding to the desired printed circuit conductor pattern are plated with a metal layer of a desired thickness without prior electroless metal plating. A process for producing a plate, comprising: (a) electrolytic plating of a defined electrical conductivity, comprising a counter electrode and containing the metal B to be electrolytically plated selected from group b or group of the Periodic Table of the Elements in ionic form; preparing a container containing a bath solution, the non-metallic part comprising a conductive connector part;
(b) positioning this connector section adjacent to the outside of the non-metallic surface to be electrolytically plated, and using this adjacent connector section as an electrode during electroplating; (c) forming a number of discontinuous metal seats consisting of or including a metal A selected from the group consisting of and Au, but different from metal B; The sheet has a specified electrical conductivity, and further the deposition rate of metal B is higher on the metal sheet consisting of or containing metal A than on the electroplated surface consisting of metal B. (d) initiating electrolytic plating of metal B onto the exposed portion of the connector portion between the connector portion and the counter electrode; A potential difference sufficient to permit electrolytic plating of metal B onto the adjacent metal seat is applied between the connector section and the counter electrode, and application of this potential difference causes electrolysis of metal B onto the connector section and the adjacent metal seat. Start plating and electroplating of metal B onto the connector portion covers the connector portion with metal B; (e) Continue applying the above potential difference until all adjacent metal seats are covered with metal B; (f) Metal B is continuously electrolytically plated on the exposed portion of the connector portion and on the electrolytically plated seat to form a continuous conductive film of Metal B having a thickness of at least 0.5 microns. A method of manufacturing printed circuit boards. 26. A method as claimed in claim 25, characterized in that the connector portion covers the surface of the insulating sheet in small areas along its edges and is shaped like a window frame. 27. A method of manufacturing a printed circuit board comprising forming holes in a copper-clad insulating sheet or a laminate formed from a number of such sheets, and providing the walls of the holes with a metal layer: (a) a number of metal Seat (the metal of the seat is selected from the group consisting of palladium, platinum, silver and gold)
(b) In the next step, without prior electroless metal plating, from an acidic electrolytic plating bath containing copper ions and an organic compound containing 4 to 1,000,000 oxyethylene groups. Electrolytically plate copper on the hole wall,
A continuous film is formed with copper deposited on the hole wall, and (c) copper is further electrolytically plated to strengthen the continuous conductive film, thereby forming a plated through hole in the insulating sheet. A method of manufacturing printed circuit boards. 28. The method of claim 27, wherein the acidic electrolytic plating bath contains sulfuric acid.