JPH0413877B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention comprises a substrate portion and a conductor portion formed by electroless plating, and the non-plated area is coated with a silane coupling agent on the conductor portion protruding surface of the substrate portion. The present invention relates to a resin composition for applying a silane coupling agent to non-plated areas when manufacturing a printed circuit board coated with a derivative. <Prior Art> A conventional printed circuit board 1 consists of a board section 3 and a conductor section 5, as shown in FIG. In a general etching method, the conductor portion 5 is formed by dissolving and removing unnecessary portions from a copper-clad laminate using chemicals. Further, in the additive method, as shown in FIG. 11, a region of the substrate portion 13 where the conductor portion 17 is not formed (hereinafter referred to as a “non-plated region”) is covered with a resin layer 15. <Problems to be Solved by the Invention> Even with such conventional printed circuit boards 1 and 11, it was possible to meet the needs of the past. However, it has become impossible to adequately respond to the trend of miniaturization of printed circuit boards as devices become smaller and more dense in recent years. In particular, when manufacturing using the etching method, the first step is to dissolve and remove unnecessary copper foil using chemicals.
As shown in Fig. 0, there is a tendency for the conductor portion 5 to erode in a reverse tapered shape up to its base (so-called undercut phenomenon). For this reason, with miniaturization of the circuit, the conductor parts 5, 5
When the distance between the conductor parts 5 and the substrate part 3 is narrowed, this tendency becomes even stronger because the chemicals need to be circulated and flowed to the finer details, and the base part of the conductor part 5 becomes thinner considerably, causing the contact between the conductor part 5 and the substrate part 3 to become thinner. Adhesion strength is extremely reduced. Also, during solder coating, which is generally applied, solder adheres to the blank part 4 of the board part 3,
There are drawbacks such as short circuits. Furthermore, in the printed circuit board 11 shown in FIG. 11, due to the presence of the resin phase 15, as the distance between the conductor parts 17, 17 becomes narrower, hydrogen gas generated in the plating reaction becomes difficult to dissipate, and the conductor parts There is a risk that the thickness of the conductor parts 17 may vary or the resin layer 15 may be plated in a mist-like manner, which may impede the insulation resistance between the conductor parts 17 . Therefore, the present invention has the following advantages: (a) plating can be performed while promoting the dispersion of hydrogen gas by not providing a resin layer, (b) a fine circuit with a uniform thickness without undercuts can be formed, and (u) ) When manufacturing a printed circuit board using electroless plating method, which prevents solder from adhering to parts other than the conductor parts, a derivative of the silane coupling agent, which is the key to achieving each of the above objectives, is used to prevent solder from adhering to the parts other than the conductor parts. An object of the present invention is to provide a resin composition for application to a plating area. <Means for Solving the Problems> As a result of extensive studies in order to achieve the above object, the inventors of the present invention have come up with the resin composition of the invention described below. To manufacture a printed circuit board comprising a substrate part and a conductor part formed by electroless plating, and in which a non-plated area of the conductor part protruding surface of the board part is covered with a derivative of a silane coupling agent. At this time, a resin composition for applying the silane coupling agent to the non-plating area, which contains rosin, a silane coupling agent, a sulfur compound added as necessary, and a plating resist agent for acid plating. It is characterized by being an active ingredient. <Detailed Description of Means> The above-mentioned means will be described in detail below. This resin composition contains rosin, a silane coupling agent, a sulfur compound added as necessary, and a plating resist agent for acid plating as active ingredients. As for the rosin, what is commonly called rosin (pine resin) and many types of rosin extracted from other plants are effective, and Canadian balsam extracted from Canadian maple is particularly preferred. The amount of rosin blended is 3 to 50% by weight in the resin composition, preferably 15 to 30%. 3
If it is out of the range of ~50%, there is a risk that the resin composition will be destroyed by the roughening liquid in the step (a) below. Silane coupling agents refer to silanes and other silicon compounds that have the ability to chemically bond organic polymers and inorganic materials. For example, triethoxymethylsilane, trimethoxymethylsilane, triethoxyphenylsilane,
Trimethoxyphenylsilane, triethoxyvinylsilane, α-aminopropyltriethoxysilane, N-(β-aminoethyl)-α-aminopropyltrimethoxysilane, α-methacryloxypropyltrimethoxysilane, α-mercaptopropyltrimethoxy Examples include silane, ureidopropyltriethoxysilane, and the like. Its blending amount is expressed as weight% in the resin composition.
0.1-15.0%, preferably 1.5-5.0%. 0.1
If it is less than 15.0%, there is a risk that plating will precipitate in non-plated areas, while if it exceeds 15.0%, there is a risk that plating will not be applied to plated areas, which are both undesirable. In addition, at this time, the material of the substrate part 25 is inorganic,
The amount of silane coupling agent in the coating 29 must be adjusted depending on whether it is an organic substance or a mixture of both, but it is necessary to supply sufficient bonding agents to the interface of the non-plated area 26. A sufficient amount to form the derivative phase of the silane coupling agent is required and determined experimentally (see Examples in Table 1). This silane coupling agent has good compatibility with common solvents for resin compositions (ethylene glycol monobutyl ether, 2-(2-ethoxyethoxy)ethanol, etc.). Furthermore, it has good compatibility with the rosin described above and the sulfur compound described below. As described later, this silane coupling agent is mainly modified into derivatives such as silanol because the method for manufacturing a printed circuit board using the resin composition of the present invention is a water treatment system. Examples of the sulfur compound include 2-mercaptobenzothiazole, thiourea, methyl blue, methylene green, 2-imidazolidinethione, methyl orange, and taurine. By adding this sulfur compound, it is possible to reliably prevent plating from depositing in the non-plated areas in the electroless plating step (d) described below. This is thought to be due to the fact that the sulfur compound is transferred to the non-plated area while bonding with the functional group of the silane coupling agent. In this way, sulfur compounds are added as needed. The amount of this sulfur compound to be blended is only a small amount, but the amount by weight relative to the resin composition is
It ranges from 0.005 to 0.5. If it is less than 0.005%, the above prevention function may not be effective, and if it exceeds 0.5%, the sulfur component will act as a catalyst poison for formalin, which is a reducing agent, and the sulfur component will exceed the plating boundary line and reach the plating area. Each of these is undesirable because there is a risk that electroless plating may not be possible due to the effect that the plating precipitation reaction may be stopped. In addition, when the above-mentioned rosin, silane coupling agent, and sulfur compound are individually added to a plating resist agent for acidic plating, the resin composition cannot withstand strong acidic solutions such as roughening liquid (first (See each comparative example in the table). As the plating resist agent for acid plating, for example, the plating resist agent SPR-530CMT (trade name) manufactured by Sanei Chemical Co., Ltd. can be used.
This plating resist agent contains an inorganic filler. Incidentally, the above plating resist agent for acidic plating alone cannot withstand the strong acidic solution such as the roughening solution used in the step (a) below. This resin composition has durability against the strongly acidic roughening liquid, catalyst liquid, and activation liquid used in steps (a) and (c) described below. If we were to estimate the reason for this, it would be as follows (a) to (c). (a) When a silane coupling agent is not added to the resin composition of the coating 29, as shown in Fig. 3, an inorganic filler (compounded in the glazing resist agent) is added.
The grain boundaries exhibit hydrophilicity with the OH groups facing outward. In contrast, silane coupling agents (e.g. trimethoxy(methyl)silane; CH ₃ Si
When (OCH ₃ ) ₃ ) is added, it is hydrolyzed by the treatment with water in the process of the present invention, and as shown in Figure 4, the grain boundaries of the inorganic filler are CH ₃
It becomes hydrophobic with the group facing outward. Furthermore, the CH ₃ group increases the bonding strength between the inorganic filler and the organic component. Therefore, the coating 29 is formed with strong hydrophobicity and denseness on both the inner and outer surfaces.
It will not be attacked even when immersed in strong acidic solutions such as roughening solution or catalyst solution. Due to such characteristics of the coating 29, its thickness can be made as thin as possible. Therefore, it is suitable for negative printing of fine patterns. (b) Next, the coating 29 contains a sufficient amount of silane coupling agent to have the denseness and chemical resistance performance described in (a) above. This slightly excess silane coupling agent is firmly bonded to the interface of the non-plating area 26, and the coating 29
Even after peeling off with an alkaline aqueous solution, a fixed film of silanol (a derivative of a silane coupling agent) generated by hydrolysis of the silane coupling agent can remain on the interface of the non-plated region 26. Since the outermost shell phase of this silanol has H groups facing outward, it is hydrophobic and has the ability to repel hydrogen atoms, hydrogen gas, and metal ions, making it possible to completely control plating precipitation. I was able to confirm this through experiment. It has also been found that this function is also effective three-dimensionally, that is, in three-dimensional directions. Presuming this state, it is thought that the plating control phase 24 is formed on the non-plating region 26 in a semi-elliptical cross-sectional shape, like a water droplet on a lotus leaf seen in nature. (c) If the surface of the dried coating 29 is treated with an acidic aqueous solution such as hydrochloric acid or sulfuric acid, the hydrophobic function may be further enhanced, the properties described in (b) above may be enhanced, and the surface of the coating 29 may be further enhanced.
The surface of 9 becomes strong. This is because the resin composition is influenced by acid groups and the effect is promoted, and the outermost monomolecular phase or a part of the phase of the silanolized phase on the surface of the coating 29 is converted into silica gel. Alternatively, it is considered that the bond between the silanol and the organic component becomes stronger. Next, a method for manufacturing a printed circuit board using the above resin composition will be explained. (A) Step of coating the non-plated area 26 of the substrate section 25 with the resin composition The substrate section 25 is a plate-shaped member capable of supporting the conductor section 23, and the material for forming it is not particularly limited. Examples include plastics, ceramics, glass, semiconductors, and laminates thereof. Further, the conductor portion 23 in the substrate portion 25
The protruding surface may be a curved surface. The resin composition is diluted with the above-described solvent and screen printed onto the substrate portion 25 (see FIG. 2). The thickness of the coating 29 thus obtained is 4 to 7 μm. If the thickness is less than 4 μm, there is a risk of blurring when screen printing. The thickness exceeding 7 μm is due to the denseness of this resin composition.
Not necessary. (a) Step of applying a catalyst to the plating region 27 of the substrate portion 25 First, it is necessary to roughen the plating region 27 of the substrate portion 25 with a roughening liquid. As the roughening liquid, when the substrate part 25 is made of resin, a mixed aqueous solution of chromic acid + sulfuric acid, chromic acid + sulfuric acid + phosphoric acid, sulfuric acid + phosphoric acid, etc. is used. Sometimes, a hydrofluoric acid solution is used.
When the substrate portion 25 is immersed in these roughening liquids, the plating area not protected by the coating 29 will be roughened. Next, a catalyst is applied to the plating area. For example, when using palladium as a catalyst,
The substrate part 25 is immersed in a mixed solution of palladium chloride and hydrochloric acid (catalyst liquid) to support palladium on the substrate part 25, and the palladium is immersed in a mixed solution of tin chloride and hydrochloric acid (activation liquid). This is done in the activation process. Of course, a process using a one-component catalyst liquid may also be used. Moreover, the type of catalyst is not particularly limited. (C) Step of removing the coating 29 from the non-plating area 26 In this step, even if the coating 29 has acid resistance, it is decomposed by an alkaline aqueous solution. 25 is immersed in the water. At this time, the state of the interface between the coating 29 and the non-plated region 26 of the substrate portion 25 is such that the silane coupling agent contained in the coating 29 (which does not contribute to imparting the above-mentioned properties to the coating 29) ) plays an important role. That is, when the coating 29 is printed on the substrate 25, one of the bonding groups of the organic and inorganic functional groups of the silane coupling agent acts selectively depending on the material of the substrate 25. , which is firmly bonded to the substrate interface and covers the non-plated area 26. Therefore, when the coating 29 is removed with an alkaline aqueous solution, this interface is also hydrolyzed at the same time, so that the fixed silane coupling agent phase is denatured into silanol and left at the interface of the non-plated area 26. Ru. If the phase of the derivative of such a silane coupling agent forms a monomolecular thin phase, it will be sufficient to meet the above-mentioned requirements.
The effect of (b) can be achieved. In other words, it is possible to make the surrounding area of the non-plated region 26 hydrophobic, to prevent the approach of hydrogen ions, hydrogen gas, and metal ions, and to prevent plating from depositing in the non-plated region 26. . (d) Step of forming the conductor portion 23 in the plating region 27 of the substrate portion 25 by electroless plating This step is performed by immersing the substrate portion 25 in an electroless plating solution. When the substrate part 25 is immersed in the plating liquid, hydrogen or hydrogen gas is generated from the plating area to which the catalyst is applied, and plating is started. A plating control phase 24 is formed. Therefore, plating is prevented from depositing in the non-plated region 26, and the plating control function affects three dimensions at the boundary with the plating region 27, so that plating is prevented from being deposited in the non-plated region 26. Growth that protrudes into the plating area 26 is controlled. Therefore, the plating (conductor portion 23) can be formed to have a predetermined rectangular cross section. Moreover, at this time, since the plating control phase 24 has a hydrogen gas repulsion function,
This promotes the dissipation of excess hydrogen gas generated from the plating region 27. Therefore, plating can be efficiently applied to the plating regions 27 that are closely spaced at minute intervals. Note that the type of plating metal is not particularly limited, and is determined depending on the relationship with the catalyst. It has also been found that this plating control phase 24 has the property of not allowing any solder to adhere to the non-plated areas 26 when it is immersed in a molten solder bath for solder coating. This means that the non-plating area 26 is made of a derivative of a silane coupling agent, or is made of molten solder (260°C).
This is thought to be due to the fact that it is coated with silicon oxide that has been denatured by heating. <Effects of the Invention> As explained above, the resin of the present invention contains a predetermined blend of rosin, a derivative of a silane coupling agent, a sulfur compound added as necessary, and a plating resist agent for acid plating as active ingredients. A print comprising a substrate part and a conductor part formed by electroless plating according to a composition, and a non-plated area on the protruding surface of the conductor part of the substrate part is coated with a derivative of a silane coupling agent. A substrate can be manufactured. Here, the resin composition of the present invention can withstand strongly acidic solutions such as plating solutions, and can apply a silane coupling agent derivative to non-plated areas of the substrate portion. <Examples> Hereinafter, resin compositions of Examples of the present invention will be described together with a method for using the same (a method for manufacturing a printed circuit board). (a) Step of coating the non-plated area of the substrate portion with a predetermined resin composition (see Figures 5 and 6) A resin composition having the formulation shown in Table 1 is prepared. On the other hand, as the substrate part 35, ABS with a thickness of 3 mm is used.
board (expressed as organic material in Table 1) and thickness 0.8
mm alumina ceramics (alumina purity: 96
%) plates (expressed as mineral in Table 1) are prepared. Note that the vertical and horizontal lengths of the plate are not particularly limited. A through hole 32 is bored into the substrate portion 35 as shown in FIG. After that, as shown in Figure 6, the first
Screen print with the resin composition shown in the table,
A coating 39 is formed. On the surface of the substrate portion 35 , the surface covered with this film 39 becomes a non-plated region 36 . The distance between one coating 39 and the other coating 39 can be narrowed to a minimum of 70 μm. Coating 39
The thickness should be at least 4 μm. This thickness is the thickness obtained by performing normal screen printing once. The fact that only a thin film can be printed in this way means that a clearer pattern can be obtained. Thereafter, the substrate portion 35 provided with the coating 39
Dry at 120°C for 15 to 20 minutes. The outer surface of the coating 39 in this state becomes hydrophobic. (a) Step of applying a catalyst to the plating area 37 of the substrate portion 35 (see FIG. 7) In order to apply a catalyst, it is first necessary to roughen the plating area 37. Prepare a roughening liquid 1 with the following composition, and add an organic substrate 35 to it while keeping it at 45 to 60°C.
Soak for 20 minutes. Roughening liquid 1 Chromic acid trioxide 30g Sulfuric acid (specific gravity; 1.84) 500ml Phosphoric acid (specific gravity; 1.7) 100ml Water with a total volume of 1 ~ Total 1 On the other hand, when the substrate portion 35 is inorganic, 46%
Keep the hydrofluoric acid solution at room temperature and add it to this
Soaked for 10-20 minutes. Thereafter, each substrate portion 35 (including the coating 39) was washed with water, and its condition was visually observed. Note that the entire surface of the substrate portion 35 without the coating 39 is roughened (becomes a plating region 37). The results are shown in Table 1. From the results in Table 1, it can be seen that the resin compositions of Examples did not deteriorate and maintained their hydrophobicity. On the other hand, the resin composition of the comparative example disappeared. According to the studies conducted by the present inventors, it has been confirmed that the resin compositions of the examples have corrosion resistance even with respect to the roughening liquids 2 and 3 for organic substrates having the following formulations. Roughening liquid 2 Chromic acid trioxide 100g Sulfuric acid (specific gravity; 1.84) 420ml Phosphoric acid (specific gravity; 1.7) 200ml Water to a total volume of 1 ~ Total 1 Roughening liquid 3 Chromic acid trioxide 500g Sulfuric acid (specific gravity; 1.84) 250ml Total volume water with 1 to total 1 Next, the substrate portion 25 is immersed in a catalyst liquid having the following composition. Catalyst liquid PdCl ₂ 1.0 g SnCl _{2.2H 2} O 50 g HCl (37% solution) 400 ml Water to a total volume of 1 ~ Total 1 The immersion conditions are 25 to 50°C x 15 to 5 minutes.
As a result, the catalyst substrate is adsorbed onto the plating region 37 of the substrate portion 35. Almost no catalyst substrate is adsorbed on the surface of the coating 39. This is presumed to be due to electrochemical repulsion caused by the silane coupling agent in the resin composition forming the coating 39. After washing the substrate portion 35 (including the coating 39) with water, the substrate portion 35 is immersed in an activation liquid having the following composition. Activating liquid HCl (37% solution) 100 ml Water to a total volume of 1 ~ Total 1 The immersion conditions are room temperature x 2 minutes. This activates the catalyst substrate in the plating area. Then wash with water. (C) Step of removing the coating 39 of the resin composition (8th step)
(See figure) The substrate portion 35 (including the coating 39) is immersed in a stripping solution having the following composition. Stripping liquid NaOH 200g Water to a total amount of 1 ~ Total 1 Immersion conditions are room temperature x 2 to 3 minutes. As a result, the coating 39 is gelled, and by washing with water,
It is peeled off from the non-plated area 36 of the substrate portion 35. Even if the coating 39 is peeled off from the non-plating area 36, the derivative of the silane coupling agent is transferred to the non-plating area 36 to form a plating control phase, as described above. (d) Step of forming the conductor portion 33 in the plating area 37 of the substrate portion 35 by electroless plating (see Fig. 9) Using plating solutions 1, 2, and 3 of the following composition, plating is performed under the following conditions. Electrolytic plating was performed. Plating solution 1 (Cu plating) CuSO ₄・5H ₂ O 10g EDTA−4Na 35g HCHO (37% aqueous solution) 10ml 2,2′−Bipy 10ml K ₄ Fe (CN) ₆・3H ₂ O 50ml Surfactant Small Amount NaOH Amount to adjust to PH12.4 Water to make the total amount 1 ~ Total 1 Plating conditions 70℃ x 50 hours Plating solution 2 (alkaline Ni plating) NiCl ₂・6H ₂ O 30g NaH ₂ PO ₂・H ₂ O 10g Na ₃ C ₆ H ₅ O ₇・2H ₂ O 75g NH ₄ Cl 50g NH ₄ OH Amount to adjust pH to 8.5-9.5 Water to make the total amount 1 ~ Total 1 Plating conditions 90℃ x 10 hours plating Solution 3 (acidic Ni plating) NiCl ₂・6H ₂ O 30g NaH ₂ PO ₂・H ₂ O 10g Na ₃ C ₆ H ₅ O ₇・2H ₂ O 25g NH ₄ Cl Amount to adjust to PH5.0-6.0 Total amount Water with 1 ~ Total 1 Plating conditions 90℃ x 10 hours As a result, as shown in Figure 9, the plating area 37
A conductor portion 33 is formed thereon. The non-plated areas 36 are coated with a derivative of a silane coupling agent. Therefore, the non-plating area 36 is in the solder repulsion phase (=plating control phase 3).
4) will be provided. According to the inventor's study, when the substrate part 35 after the conductor part 33 is immersed in a molten solder bath for 10 seconds,
No solder adhered to the non-plated area 36 at all. This confirmed the effect of isolating the solder in the solder repellent phase in the non-plated area 36. On the other hand, when an experiment similar to the above was conducted on a printed circuit board that was not coated with a silane coupling agent, solder adhered to various parts of the non-plated areas 36. The cross-sectional shape of the conductor portion 33 of the printed circuit board 31 of the embodiment formed in this way is as follows:
I got up straight from 7. Table 2 shows the dimensions of the cross section of the conductor portion formed using plating liquid 2 in a band-shaped plating region of a constant width. Each dimension of the conductor part was obtained by taking a microscopic photograph of the cross section of the conductor part and measuring it with a caliper. The resin compositions used were those for coating the non-plated areas, and Examples 1, 3, and 5 in Table 1 were used. The reason why the cross-sectional shape of the conductor portion rises straight from the plating region is considered to be due to the action of the plating control phase. When electroless plating is performed with the non-plated area of the substrate not covered with the silane coupling agent derivative, the width of the plating increases within 5 to 10 minutes from the start of plating, and the width of the plating increases within 30 to 60 minutes. This developed into so-called "stickiness" on the entire surface of the board.

【table】

【table】

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a printed circuit board 21 of the present invention, FIG. 2 is a cross-sectional view showing a state in which a film 29 is formed by screen-printing a resin composition on a substrate portion 25, and FIG. FIG. 4 is a schematic diagram showing the inorganic filler in the resin composition when it is not blended, and FIG. 5 is a schematic diagram showing the inorganic filler in the resin composition when the silane coupling agent is blended. 6 is a cross-sectional view showing the substrate part 35 of the example, FIG.
A cross-sectional view showing a state in which a catalyst has been applied to the plating area 37 of the figure, and FIG. 8 is a coating 39 of the figure 7.
FIG. 9 is a cross-sectional view showing the printed circuit board of the embodiment, with the 10th and 11th
The figure is a sectional view of a conventional printed circuit board 1, 11. 1, 11, 21, 31... printed circuit board, 3,
13, 25, 35...Substrate part, 5, 17, 23,
33...Conductor part.

Claims (1)

[Scope of Claims] 1. Comprised of a substrate portion and a conductor portion formed by electroless plating, wherein a non-plated area on the protruding surface of the conductor portion of the substrate portion is made of a derivative of a silane coupling agent. A resin composition for applying the silane coupling agent to the non-plated area when manufacturing a coated printed circuit board, the resin composition comprising: rosin; 3 to 50% by weight; silane coupling agent; 0.1 to 15% by weight. Weight%, sulfur compounds added as necessary; 0.005~
A resin composition comprising: 0.5% by weight, a plating resist agent for acid plating; the remainder being an active ingredient.