JPH0787264B2 - Manufacturing method of ceramic wiring board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a ceramic wiring board used as an electronic base material.

[Background technology]

For metallizing ceramics, various methods such as a telefunken method, an active metal method, a thick film method, a thin film method, and a plating method have been conventionally used as needed. Among them, the plating method can directly metalize a single metal to a ceramic substrate, so that the obtained metal layer has high conductivity, the thickness of the metal layer can be easily controlled over a wide range, and the through-hole metallization is also easy. Since it has advantages such as high reliability and capable of forming a fine pattern, research for practical use is being conducted.

Conventionally, a ceramic wiring board by a plating method has been manufactured by a batch process in which the following operations (a) to (e) are sequentially performed.

(A) Preparation of ceramic substrate (b) Substrate surface roughening treatment (c) Substrate cleaning and drying treatment (d) Substrate surface activation treatment (e) Electroless plating treatment As described above, (a) to ( Although a ceramic wiring board is obtained through the process of e), when manufacturing a wiring board by these processes, batch processing was performed as described above, so there was a large variation in the characteristics from lot to lot, and the yield decreased. As a result, cost increase is unavoidable, and these improvements have been desired.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for manufacturing a ceramic wiring board, which has less variation in characteristics and can be manufactured at low cost.

[Disclosure of Invention]

The present invention comprises a step of immersing a sintered ceramic substrate in a phosphoric acid treatment solution to roughen its surface, a step of cleaning the treatment solution after the roughening treatment, and electroless plating on the roughened substrate. A method for manufacturing a ceramic wiring board including a step of forming a metal layer and continuously performing all steps up to the formation of the metal layer, wherein the roughening step includes a phosphoric acid treatment solution continuous regeneration step. Is a step of adding water to the phosphoric acid treatment solution sent from the roughening step to hydrolyze condensed phosphoric acid in the phosphoric acid treatment solution, and treating unnecessary reaction products generated by the hydrolysis with phosphoric acid. The step of removing from the solution, the step of adjusting the phosphoric acid concentration of the phosphoric acid-treated solution by adding new phosphoric acid to the phosphoric acid-treated solution from which unnecessary reaction products have been removed, and the phosphoric acid concentration were adjusted Send the phosphoric acid treatment solution to the roughening process. The preparation of the ceramic wiring board which comprises a step of returning it is an gist.

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment thereof.

First, the manufacturing process of the ceramic wiring board according to the present invention
Shown in the figure.

The manufacturing process will be described below with reference to FIG.

A sintered ceramic substrate is prepared. As the material of the sintered substrate, oxide type ceramics such as alumina, forsterite, steatite, zircon, mullite, cordierite, zirconia and titania are mainly considered.
Carbide-based and nitride-based ceramics can also be used.

Degrease the prepared ceramic substrate. Degreasing is performed in order to improve the wettability of the treatment liquid in the subsequent steps.

 Wash degreasing liquid with water.

It is immersed in a roughening treatment solution to roughen the substrate surface. Roughening is performed in order to exert an anchor effect at the time of forming the metal layer, and as the roughening treatment solution, the adhesion does not decrease even if the roughening treatment solution remains, and adversely affects the chemical plating metal. At least one phosphoric acid solution selected from the group consisting of orthophosphoric acid, metaphosphoric acid, and pyrophosphoric acid is used. The processing temperature is preferably 250 ° C to 360 ° C. This is 25, as you can see in Figure 3.
This is because the etching ability is low at a treatment temperature of 0 ° C. or lower, and decomposition or condensation becomes severe even at 360 ° C. or higher, so that the etching ability is also low. The degree of roughening depends on the immersion time, but the immersion time is 1 to 30 minutes, preferably 3 to 10 minutes. Borax, V ₂ O ₅ , HF, alkali metal compounds, etc. can be considered as the roughening solution, but they can roughen the surface layer of the substrate densely and, in addition, improve the adhesion to the metal layer formed on the surface. It is the phosphoric acid solution that meets the requirement of not affecting.

By the way, it is possible to roughen the ceramic surface layer by etching HF at 90 ° C, which is generally well known, but if a small amount of HF remains, the etching will proceed gradually and the ceramic substrate will Deteriorates or corrodes the electroplated metal layer. Further, it is impossible to make a fine and uniform rough surface.

The roughened substrate is washed. Since the roughening is performed by the phosphoric acid treatment liquid, the reaction product with the phosphoric acid treatment liquid remains on the surface of the substrate after the roughening. Therefore,
The surface of the roughened substrate is washed with warm water or water. If necessary, then dry.

The surface of the roughened substrate is activated. This is a step of activating the substrate surface by applying a catalyst that serves as a receptor for electroless plating. In the activation step, generally, a sensitizing step of adsorbing divalent tin ions on the substrate surface using a stannous chloride solution and a palladium chloride solution are used, and metallic palladium is added to the substrate surface by the action of the tin ions. The sensitizing-activating method, which comprises an activation step of precipitating in, is used, but it is also possible to use an emulsion type activator. When the sensitizing-activating method is used for the activation step, it is necessary to add a water washing step between the sensitizing step and the activation step.

Electroless plating is applied to form a metal layer on the substrate surface.
This is usually done by chemical copper plating, chemical nickel plating, or the like. The thickness of the metal layer is about 0.8 to 10 μm.

The ceramic wiring board manufacturing apparatus according to the present invention is adapted to carry out the above steps at least continuously.

If necessary, electrolytic plating is performed. In the case of electrolytic plating, if the required metal layer is thick, after performing the chemical plating on the substrate, copper plating, or when using this wiring board for digital signal circuits, electroless plating is used. The thickness of the obtained metal layer is sufficient, but when it is used as a wiring board for high power, it is thickened by electrolytic plating.

Surface treatment is performed as necessary. The surface treatment is a preparation step for chemically polishing the surface of the metal surface after electrolytic plating with a solution such as sulfuric acid to draw a circuit pattern.

If necessary, a circuit is formed by etching. The necessary circuit may be formed immediately by chemical plating or electrolytic plating thereon, but it is general that the subtractive method is used to form a circuit by etching by plating the entire surface of the substrate. .

It should be noted that the steps 1 to 3 may be performed by different devices.

FIG. 11 schematically shows an embodiment of an apparatus using the method for manufacturing a ceramic wiring board according to the present invention.
As shown in the figure, this ceramic wiring board manufacturing device
Degreasing device 19, Degreasing liquid cleaning device 20, Phosphoric acid treatment device 21, Sensitizing treatment device 22, Sensitizing treatment liquid washing device 23, Activation treatment device 24, Activation treatment liquid washing device 25, Electroless plating device 26, Electrolytic plating equipment
27, a surface conditioning treatment device 28, a surface conditioning treatment liquid cleaning device 29, and a drying device 30, which are twelve small devices, and each device is arranged in the order described above. Each apparatus is provided with a transfer means, and the transfer means guides the substrate sent from the previous step to the inside of the processing tank for processing and sends it to the next step.

Except for the phosphoric acid treatment equipment 21 and the drying oven 30,
As shown in the figure, processing tank 11, ultrasonic cleaning tank 12, dryer 13,
Further, it is provided with a carrying belt 14 as a transfer means. The processing bath 11 contains a processing liquid corresponding to each process. For example, in the degreasing device 19, trichlene, acetone or the like is used as the treatment liquid, and the cleaning devices 20, 23, 2
At 5,29 water is used. The ultrasonic cleaning tank 12 is the processing tank 11
It is provided below and is equipped with an ultrasonic cleaning device and the like.
As shown in FIG. 8 (a), the carrying belt 14 is endless with a large number of belt pieces 14 a connected so as to be bendable so as to circulate through the processing tank 11, the ultrasonic cleaning tank 12 and the dryer 13. By changing the patrol speed, the immersion time of the substrate in the processing bath 11 can be changed freely. A mesh 15 is formed at the center bottom of each belt piece 14a. As shown in FIG. 8B, the substrate 2 sent from the previous step is placed on the carrying belt 14 and immersed in the processing liquid in the processing tank 11 together with the carrying belt 14. The carrying belt 14 coming out of the processing tank 11 sends the processed substrate 2 to the next step, and then is inverted and enters the ultrasonic cleaning tank 12. Ultrasonic treatment tank
At 12, the carrying belt piece 14a is washed. The cleaned carrying belt piece 14a is dried by the dryer 13 and receives the new substrate 2 sent from the previous step,
It is adapted to be immersed again in the processing tank 11. The material of the carrying belt 14 is generally formed of metal such as stainless steel, and the surface thereof is coated with a resin having acid resistance and alkali resistance such as fluorine resin and polypropylene. The mesh 15 is provided so that the back surface of the substrate 2 can be processed well when it is dipped in the processing liquid, and that the mesh 15 is well drained when it is removed from the processing liquid. Electrolytic plating section 27, carrying belt
14 is made of copper and serves as a cathode in the treatment tank 11, and as shown in FIG. 9, two anodes 17, 17 made of copper are used.
Are arranged so as to sandwich the carrying belt 14 and the substrate 2. The treatment bath 11 and the ultrasonic cleaning bath 12 differ depending on the type of treatment liquid, but are not particularly limited as long as they have acid resistance and alkali resistance. Generally, vinyl chloride is used.

As shown in FIG. 6, the phosphoric acid treatment device 21 includes a treatment liquid tank 5,
A dryer 10 and a cleaning tank 6 having three tanks of a first tank 7, a second tank 8 and a third tank 9 are provided, and each tank is circulated.
The substrate 2 sent from the previous step (degreasing liquid cleaning device 20) is immersed in each tank in order, and then the endless belt 4 is carried to the next step (sensitizing device 22). A phosphoric acid treatment liquid is put in the treatment liquid tank 5. The temperature of the treatment liquid is controlled to a desired temperature of 250 ° C to 360 ° C. Phosphoric acid is dehydrated and condensed by heating, and the degree of condensation changes from moment to moment depending on the heating time, which lowers the activity of the phosphoric acid treatment solution and affects the degree of roughening of the substrate. However, the treatment liquid tank 5 is provided with a continuous regeneration means for hydrolyzing the condensed phosphoric acid and newly adding phosphoric acid if necessary to keep the activation degree of the treatment liquid in the treatment liquid tank 5 constant at all times. I have it. The system will be described in detail with reference to FIG.

The treatment liquid is drawn out from the bottom of the treatment liquid tank 5, gradually cooled to 70 to 100 ° C., and then fed to a hydrolysis tank (not shown).

Add water to the processing liquid sent to the hydrolysis tank, and add 3
Higher-order condensed phosphoric acid higher than phosphoric acid is decomposed to orthophosphoric acid or pyrophosphoric acid.

The amount of water added in the hydrolysis tank is 0.5 l to 4 l with respect to the treatment liquid 1.

The reaction product contained in the hydrolyzed phosphoric acid is removed by filtration.

The filtered phosphoric acid is sent to a phosphoric acid injection tank (not shown).

Add new phosphoric acid so that the concentration of phosphoric acid sent in will be the concentration of the processing solution.

The phosphoric acid having the treatment liquid concentration is sent to the preheating tank by a chemical pump to preheat it to the temperature of the treatment liquid, and then the phosphoric acid is sent to the treatment liquid tank 5.

The amount of new phosphoric acid added is controlled automatically in the treatment liquid tank 5 by constantly sampling the treatment liquid, measuring the concentration of phosphoric acid and the degree of condensation of phosphoric acid, and automatically controlling the results. It has become so. The portions of the treatment liquid tank 5 and the continuous regenerating means that come into direct contact with phosphoric acid are made of quartz, which is excellent in corrosion resistance to high-temperature phosphoric acid.

On the other hand, the cleaning tank 6 is for removing phosphoric acid and reaction products adhering to the substrate 2 processed in the processing liquid tank 5, and the first tank 7 and the second tank 8 have 80- Hot water heated to 100 ° C. is put therein, water is put in the third tank 10, and each tank is equipped with an ultrasonic cleaning device (not shown).
Since each of the tanks 7, 8 and 9 does not come into contact with high temperature phosphoric acid, stainless steel coated with fluorine resin or polypropylene resin is used.

As shown in FIGS. 5 (a) and 5 (b), hooks 3 made of a fluororesin are attached to the belt 4 over the entire circumference of the belt 4 at regular intervals, and the hooks 3 hang the carrier. It can be lowered. This carrier 1 is the substrate 2
And circulates each tank together with the belt 4 and the substrate 2 and its lower part are immersed in the processing liquid in each tank. The carrier 1 is also made of quartz like the processing liquid tank 5. Substrate 2 from the degreasing liquid cleaning tank 20
Is transferred to the phosphoric acid processing device 21, is automatically placed on the carrier 1, and the belt 4 is moved to move the processing liquid tank 5 and the cleaning tank 6 to the first position.
The tank 7, the second tank, and the third tank are soaked in order in each tank.

Of course, also in this device 21, the time during which the substrate is immersed in the processing liquid can be freely changed by adjusting the speed of the belt 4.

The drying device 30 is also provided with the carrying belt 14 so that the plating substrate sent from the previous step (the surface treatment liquid cleaning device 29) can be dried by the dryer. of course,
The carrying belt 14 can also freely change the speed.

In the above embodiment, the treatment liquid tank 11 of each cleaning device 20, 23, 25, 29.
Is filled with water, and the substrate sent by the carrying belt 4 is immersed in the cleaning so that the cleaning can be performed by spraying water from the vertical direction of the belt 4 with a spray or a shower. It doesn't matter.
It is preferable that the cleaning water of the cleaning devices 25 and 29 after each plating device is sent to a recovery device, concentrated, and returned to the treatment tank 11 of each plating device, because the loss of the plating solution can be eliminated. The dryer 30 only needs to have a function of drying. The device for performing the non-essential step may be omitted.

Next, examples will be described.

(Example 1) As the manufacturing apparatus, those up to the electroless plating apparatus 26 of the ceramic wiring board manufacturing apparatus described in the above-mentioned example were used. Triclen was placed in the processing tank of the degreasing device 19 and the speed of the carrying belt 14 was adjusted so that the immersion time of the substrate was 3 to 5 minutes. Water was put in the processing tank of the degreasing liquid cleaning device 20, and the speed of the carrying belt 14 was adjusted so that the immersion time of the substrate was 3 to 5 minutes. While maintaining the phosphoric acid temperature of the phosphoric acid treatment liquid tank 5 of the phosphoric acid treatment device 21 at 330 ° C.,
The concentration of orthophosphoric acid was kept at 25 to 35% by the continuous regeneration means, and the speed of the belt 4 was adjusted so that the immersion time of the substrate was 5 minutes. The first tank 7 and the second tank 8 of the cleaning tank 6
Was heated to 80 to 100 ° C., and water was added to the third tank 9. The immersion time of the substrate in each tank of the cleaning tank 6 is 3 to
It was 5 minutes. A commonly used stannous chloride solution was placed in the treatment liquid tank of the sensitizing device 22, and the speed of the carrying belt 14 was adjusted so that the immersion time of the substrate was 2 minutes. A commonly used palladium chloride solution was put in the treatment tank of the activation device 24, and the speed of the carrying belt 14 was adjusted so that the immersion time of the substrate was 1 minute. Water was put in the treatment tanks of the cleaning tanks 23 and 25 arranged after the sensitizing device 22 and the activation device 24, and the speed of the carrying belt 14 was adjusted so that the immersion time of the substrate was 1 minute. Electroless plating equipment 26
A high-speed thickening type commercially available electroless copper plating solution is put in the treatment tank of, and the temperature is kept at 55 ° C. The speed of the carrying belt 14 is adjusted so that the immersion time of the substrate is 3 hours.
Adjusted to 5 cm / min. Prepare three types of alumina substrates with 92,96,99% alumina content as ceramic substrates,
Using the ceramic wiring board manufacturing apparatus prepared as described above, a ceramic wiring board having a copper plating layer of 10 μm formed on both surfaces was obtained. The substrate surface roughness Rmax after the phosphoric acid treatment was 2.5 μm (92%), 4 μm (96%), and 10 μm, respectively.
It was within ± 1 μm in μm (99%). The thus obtained wiring board was further subjected to thick plating by electrolytic plating to make the thickness of the copper plating layer 35 μm, the peel strength was measured, and the adhesion between the board and the copper plating layer was measured. , 1.9kg / cm (92%), 1.4kg / c, respectively
With m (96%) and 1 kg / cm (99%), it was possible to suppress variations within ± 5%. Further, when a 96% alumina substrate was used for a long time and the time course of the substrate surface roughness Rmax obtained by the phosphoric acid treatment was examined, as indicated by the ● in FIG. It was possible to supply a substrate having a stable surface roughness to the next step with almost no change. The peel strength used in the examples means the peel strength when the copper layer 18 having a width of 1 cm is pulled up in the vertical direction as seen in FIG.

Comparative Example 1 Obtained by phosphoric acid treatment in the case where this apparatus was used for a long time in the same manner as in Example 1 except that the phosphoric acid treatment apparatus of Example 1 was a batch type without a continuous regeneration means. When the time-dependent change of the surface roughness Rmax of the substrate to be processed is examined, the surface roughness Rm of the substrate treated 1 hour after the start of the immersion treatment and the substrate roughness Rm as shown by the circle in FIG.
ax was very different. Since the surface roughness Rmax greatly affects the adhesion between the substrate and the copper layer, the variation of the peel strength of the obtained wiring board reaches up to 40%.

(Example 2) After the electroless plating apparatus 26, an electroless plating solution cleaning apparatus,
The plating surface activating device and the electrolytic plating device 27 were added to the device of the first embodiment. Electroless plating equipment of this equipment
The processing solution in the 26 processing tanks was a normal temperature type chemical copper plating solution maintained at 25 ° C, and the speed of the carrying belt 14 was adjusted so that the immersion time of the substrate was 20 minutes,
m copper plating layer was formed. The electroless plating solution cleaning device and plating surface activating device have the same structure as other cleaning devices.Put water in the treatment tank of the electroless plating solution cleaning device and adjust the speed of the carrying belt 14. The immersion time was set to 1 minute. On the other hand, 10% sulfuric acid was put in the treatment tank of the plating surface activating device and the substrate was immersed for 1 to 2 minutes to activate the surface of the chemical copper plating. Sulfuric acid plating solution is placed in the processing tank of the electrolytic plating device 27.
The substrate was held at 25 ° C., the speed of the carrying belt 14 was adjusted so that the substrate was immersed for 80 minutes, and a copper plating layer having a thickness of 35 μm was formed on both sides of the substrate at a current density of ² A / dm ² . . The steps other than the above were performed under the same conditions as in Example 1.

(Example 3) Except that instead of dipping the washing with a washing device, water was sprayed from above and below the carrying belt.
A wiring board was obtained in the same manner as in Example 1.

Also in the devices of Examples 2 and 3, similar to Example 1, wiring boards having no variation in characteristics were continuously obtained.

The manufacturing apparatus using the method for manufacturing a ceramic wiring board according to the present invention is not limited to the above embodiment. For example, although the copper layer is formed as the metal layer in the embodiments, other conductors such as nickel may be used. In the embodiment, palladium serving as an active site is deposited on the substrate surface by sensitizing and activation, but an emulsion type activator may be used. The subtractive method is generally used for circuit formation, but of course the additive method or the semi-additive method can be applied. In the case of forming a circuit by these methods, a plating resist may be applied in a desired pattern, and a step of removing an unnecessary conductor portion by etching or the like may be added. In the embodiments, the subtractive circuit forming method using the photo method is used, but the circuit forming may be performed by screen printing. In the embodiment, the ultrasonic cleaning device is used for each cleaning device, but it does not have to be provided. However, it is more efficient to use ultrasonic cleaning together.

〔The invention's effect〕

As described above, according to the method for manufacturing a ceramic wiring board of the present invention, the steps up to the electroless plating step are continuously performed, and the phosphoric acid treatment liquid is always activated stably by the continuous regeneration step. Since the state can be maintained, there is little variation in characteristics such as adhesion between the substrate and the metal plating layer, and the ceramic wiring substrate can be manufactured at low cost.

In particular, in the continuous regeneration step of the phosphoric acid-treated solution, condensed phosphoric acid that reduces the degree of activation of the phosphoric acid-treated solution is hydrolyzed by adding water to the phosphoric acid-treated solution and hydrolyzing it easily and efficiently. Can be removed. While the roughening process of the ceramic wiring board is continuously performed in the roughening process, the phosphoric acid treatment solution whose activation degree has decreased can be continuously regenerated in the phosphoric acid treatment solution continuous regeneration process. The activation degree of the phosphoric acid treatment solution used can always be kept constant.
As a result, as described above, the phosphoric acid treatment liquid continuous regeneration step is also incorporated in the production line that continuously performs each step including the roughening step of the ceramic wiring board, and the roughening step is always performed with a constant processing quality. It will be possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing one embodiment of a process of manufacturing a ceramic wiring board according to the present invention, FIG. 2 is a block diagram showing one embodiment of a process of continuous regeneration means of phosphoric acid, and FIG. FIG. 4 is a graph showing the relationship between the phosphoric acid treatment liquid temperature when using the regenerating means and the substrate surface roughness. FIG. 4 shows the treatment liquid treatment when the continuous regenerating means is used and when the batch type is used. FIG. 5 (a) is a side view showing one embodiment of a carrier used in the phosphoric acid treatment apparatus, and FIG. 5 (b) is a graph showing the change over time in the ability (influence on the substrate surface roughness Rmax). FIG. 6 is a side view showing a state in which the ceramic substrate is placed, FIG. 6 is a schematic diagram illustrating one embodiment of a phosphoric acid processing apparatus, and FIG. 7 is a schematic illustrating one embodiment of a processing apparatus other than the phosphoric acid processing apparatus. Fig. 8 (a) shows the carrying belt. 1 is a partial perspective view showing an embodiment,
FIG. 8 (b) is a partial perspective view showing a state in which the ceramic substrate is placed, FIG. 9 is a side sectional view illustrating a processing tank of an electrolytic plating apparatus, and FIG. 10 is a side view illustrating a peel strength measuring method. 11 and 12 show a ceramic wiring board manufacturing apparatus to which the method for manufacturing a ceramic wiring board according to the present invention is applied.
It is a schematic diagram explaining an Example. 2 ... Ceramic substrate, 18 ... Copper layer (metal layer), 21 ... Phosphoric acid treatment device, 26 ... Electroless plating device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Ogawa 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (56) References JP-A-61-140195 (JP, A) JP-A-61-151081 ( JP, A)

Claims (3)

[Claims] 1. A step of immersing a sintered ceramic substrate in a heated phosphoric acid treatment solution to roughen its surface, a step of cleaning the ceramic substrate after the roughening treatment to remove the treatment solution, and A method of manufacturing a ceramic wiring board, comprising a step of forming a metal layer on the roughened substrate by electroless plating, and continuously performing all the steps up to the formation of the metal layer, the method comprising: The process is accompanied by a phosphoric acid treatment solution continuous regeneration process. In this phosphoric acid treatment solution continuous regeneration process, water is added to the phosphoric acid treatment solution sent from the roughening process to remove the phosphoric acid treatment solution. The step of hydrolyzing the condensed phosphoric acid of, the step of removing unnecessary reaction products generated by the hydrolysis from the phosphoric acid treatment solution, and the step of adding new phosphoric acid to the phosphoric acid treatment solution from which unnecessary reaction products are removed And add phosphoric acid treatment And adjusting the concentration of phosphoric acid, preparation of a ceramic wiring board which comprises a step of sending back the phosphating solution phosphate concentration is adjusted to the roughening step. 2. The method for producing a ceramic wiring board according to claim 1, wherein the phosphoric acid treatment solution is at least one selected from the group consisting of orthophosphoric acid, metaphosphoric acid, and pyrophosphoric acid. 3. The roughening step uses a phosphoric acid treatment solution heated to 250 to 360 ° C., and the hydrolysis step in the phosphoric acid treatment solution continuous regeneration step is the phosphoric acid sent from the roughening step. 70 ~ 10 treatment solution
A step in which water is added after cooling to 0 ° C. and the phosphoric acid treatment solution is sent back to the roughening step is heated to the treatment solution temperature of the roughening step and then sent back to the roughening step. The method for manufacturing a ceramic wiring board according to any one of the first and second aspects.