JPH0728114B2 - Method for manufacturing ceramic wiring board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a ceramic wiring board in which wiring of a desired pattern is formed on the surface of a ceramic substrate.
More specifically, the present invention relates to a method for producing high-density wiring having low resistance on the surface of a ceramic substrate at low cost and with high performance.

[Conventional technology]

Conventionally, a thin film method and a thick film method are widely known as methods for forming wiring on the surface of a ceramic substrate.

The thin film method is that after depositing a metal on the surface of a ceramic substrate,
The vapor-deposited metal is removed by etching except for the portion where the wiring is formed, to form a wiring having a desired pattern made of the vapor-deposited metal left on the substrate. Although the thin film method is suitable for high-density wiring, its application range is limited due to defects such as poor mass productivity and uneconomical, and low adhesion strength between the ceramic substrate and the deposited metal.

The thick film method is a method of forming a wiring by printing and firing a paste composed of noble metal particles, and is widely used. However, in the thick film method, since the wiring is formed by using the printing method, it is difficult to form a high density circuit in which the obtained wiring has a conductor width of 150 μm or less, and the paste has a high resistance such as glass. Since it often contains components, it has the drawback that it is difficult to form low-resistance wiring. It is not always suitable as a method for manufacturing low-resistance high-density wiring on the surface of a ceramic substrate at low cost and with high performance. Not a thing.

On the other hand, in recent years, as a method of forming low-resistance high-density wiring on a ceramic substrate at low cost and with high performance, copper plating is performed on the surface of the ceramic substrate and the plated copper on the substrate other than the portion where the wiring is formed is removed by etching. Therefore, a method for obtaining a desired wiring is being studied. Since this method uses pure metal-plated copper as a wiring material, wiring with extremely low resistance can be obtained, and since an etching method is used, it is possible to obtain wiring with high density and fine lines. . The plating method also has the advantage that it can be mass-produced and the wiring can be formed extremely economically. However, in the method of directly copper plating on the ceramic substrate,
It is not possible to sufficiently secure the adhesion strength between the ceramic substrate and the plated copper, which is a major obstacle to practical use.

In order to solve such a problem, a method of manufacturing a ceramic wiring board using nickel, which has excellent adhesion strength to the ceramic substrate, is being studied, but nickel plating has a high resistance value of the wiring. It was not suitable for low resistance wiring.

[Problems to be solved by the invention]

The present invention has been made in view of the above problems in the ceramics substrate, and a main object of the present invention is to solve the problems in the conventional ceramics wiring board and to provide a high-density wiring with low resistance at low cost. Another object of the present invention is to provide a novel method for manufacturing a ceramic wiring board that can be manufactured with high performance.

[Means for solving problems]

The present invention that achieves the above object comprises: (1) a first step of subjecting a ceramic substrate to electroless nickel plating and laminating a nickel layer on the substrate; and (2) a ceramic substrate on which the nickel layer is laminated. ,
A second step of performing electroless copper plating and / or electrolytic copper plating and laminating a copper layer on the nickel layer of the substrate; and (3) the nickel of a ceramic substrate in which the nickel layer and the copper layer are sequentially laminated. And a third step of laminating a resist layer on a portion where the copper layer and the copper layer remain, and (4) etching the ceramic substrate on which the nickel layer, the copper layer and the resist layer are sequentially laminated to laminate the resist layer. Wiring formed by removing the nickel layer and the copper layer on the substrate other than the existing portions and then removing the resist layer to leave the nickel layer and the copper layer in the portion where the resist layer was laminated. And a fifth step of subjecting the ceramic substrate on which the wiring is formed to a heat treatment, and a fifth step of subjecting the ceramic substrate on which the wiring is formed to a heat treatment. A.

That is, according to the present invention, by performing various steps including the above steps (1) to (5), a wiring having a desired pattern in which a nickel layer and a copper layer are sequentially laminated on a ceramic substrate is formed. is there.

A typical example of the ceramics substrate in the present invention is an alumina ceramics substrate containing Al ₂ O ₃ as a main component. The substrate shape can be a desired one according to the application of the ceramic wiring board to be formed, etc., but is generally a plate shape. The wiring is provided at a desired portion of such a ceramic substrate. Although it depends on the shape of the substrate, for example, if it is a plate-shaped substrate, it may be provided on only one side of the substrate or on both sides. Of course, it may be provided on all of these surfaces or only a part thereof.

In the present invention, the substrate is preferably subjected to degreasing treatment and / or etching prior to the first step of electroless nickel plating. For the degreasing treatment, a solvent such as methanol or an alkaline aqueous solution such as caustic soda is generally used.

The etching is generally wet etching using an acid such as hydrofluoric acid, kelf hydrofluoric acid, ammonium acid fluoride, hydrochloric acid, nitric acid, or an alkaline aqueous solution such as caustic soda and sodium carbonate, but is dry etching. I don't care. In addition, even if salts such as sodium chloride and potassium chloride are used in combination with an acid or an alkali, there is no problem.

In the first step of the present invention, electroless nickel plating is applied to a ceramic substrate and a nickel layer is laminated on the substrate. In this step, it is preferable to subject the substrate to sensitization and / or activation prior to electroless nickel plating. Stannous chloride solutions are commonly used for sensitization. Practically, the activation treatment is performed with an aqueous solution containing palladium or a palladium colloid, or with an aqueous solution containing silver ions and an aqueous solution containing palladium or a palladium colloid.

Specifically, the electroless nickel plating in the present invention is performed using, for example, the following combinations of electroless plating baths.

For example, 1) nickel-phosphorus plating bath nickel sulfate + sodium hypophosphite + sodium citrate III sodium 2) nickel-boron plating bath nickel chloride + DMAB ([CH ₃ ] ₂ NHBH ₃ ) + II sodium tartrate etc. .

The electroless nickel plating in the first step is easy to manufacture on the entire surface of the ceramic substrate, but it is not always necessary to apply it on the entire surface. For example, only one side of the substrate or the portion where wiring is formed is used. It is also possible to limit to the substrate surface.

The thickness of the electroless nickel plating in the first step is 0.01 in order to secure sufficient adhesion strength with the ceramic substrate and to keep the conductor resistance of the wiring formed through the first to fifth steps good. μm to 3.0 μm is preferable.

In a second step performed after the first step, a ceramics substrate having a nickel layer laminated on the surface of the first step is subjected to electroless copper plating and / or electrolytic copper plating. A copper layer is laminated on the nickel layer. The copper layer is preferably laminated so as to cover the entire surface of the nickel layer.

Electroless copper plating in the present invention, for example, EDTA, EDTA-
It is performed using an electroless copper plating solution such as a mixed solution of copper, paraformaldehyde, and 2-2'-dipyridyl. On the other hand, as the electrolytic copper plating, it is common to use a copper sulfate-based plating solution containing sulfuric acid and copper sulfate, and / or a copper pyrophosphate-based plating solution containing copper pyrophosphate, potassium pyrophosphate, ammonia, and a brightener. is there. Electrolytic copper plating is preferably performed after acid activation treatment with sulfuric acid.

An alloy layer made of nickel and copper may be formed on the nickel layer and the copper layer.

In a third step performed after the second step, a resist layer is further laminated on the nickel layer and the copper layer sequentially laminated on the ceramic substrate through the first and second steps. In the fourth step performed after the completion of this step, the resist layer is selectively laminated on the nickel layer and the copper layer to be left as wiring. The resist may be appropriately selected and used from resist ink, dry film photoresist, liquid photoresist, etc., depending on the fine line property of the pattern required for the ceramic wiring board.

In a fourth step performed subsequent to the third step, the ceramic substrate on which the nickel layer, the copper layer and the resist layer are sequentially laminated through the above first to third steps is subjected to an etching treatment, and the resist layer is The nickel layer and the copper layer on the substrate other than the portion where is laminated are removed by etching.
Then, the resist layer in the portion consisting of the nickel layer, the copper layer and the resist layer remaining on the ceramic substrate after the etching process is removed. By removing the resist, a wiring having a desired pattern in which a nickel layer and a copper layer are sequentially laminated is formed on the ceramic substrate.

The etching in this step may be either wet etching or dry etching, but if it is wet chamber etching, for example, ferrous chloride, cupric chloride, copper nitrate,
It is preferable to use an etching solution containing one kind or a combination of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid and the like. The resist may be removed by using a solvent such as acetone or trichlene or an alkaline aqueous solution such as caustic soda.

In a fifth step following the fourth step, the ceramic substrate having the wiring of the desired pattern obtained in the fourth step is heat-treated. The heat treatment is preferably carried out using an oven, a firing furnace or the like under heat treatment conditions of 50 ° C. to 400 ° C. for 5 minutes to 5 hours.

The heat treatment in this step is carried out mainly for the purpose of improving the adhesion strength between the ceramic substrate and the wiring consisting of the nickel layer and the copper layer sequentially laminated on the substrate. However, if such a heat treatment is performed in a step prior to the fifth step, the adhesion with the substrate can be improved, but the adhesion with the substrate can be improved, as shown in Comparative Example 2 described later, for example. Due to the improvement, it becomes difficult to remove the conductor from the substrate during the etching process in forming the wiring, and a problem such as a short circuit between the conductors occurs due to etching residue on the substrate. Cannot be achieved.

After the above first to fifth steps, for example, the copper oxide film on the wiring on the ceramic substrate is mechanically and / or chemically removed, or nickel is plated on the wiring or It is perfectly acceptable to perform a process such as applying gold plating and / or gold plating to improve the adhesion between the mounted component and the ceramic wiring board.

[Action]

In the present invention, nickel, which has excellent adhesion strength to the ceramics substrate, and copper, which is a low resistance material, are used to form wiring by sequentially stacking these nickel and copper on the substrate,
Low resistance that takes advantage of these copper and nickel,
Further, it is possible to obtain a ceramic wiring board having excellent adhesion to the ceramic substrate.

Further, since the wiring formed by using these nickel and copper is formed by the plating method which can form the high density wiring with high mass productivity and economically, the high density wiring and the fine line wiring are inexpensive. In addition, it can be formed with high performance.

〔Example〕

Examples will be shown below to explain the present invention in more detail.

Example 1 In this example, a ceramic substrate having a thickness of 0.
635 mm, substrate size 80 mm × 80 mm made of 96% pure Al ₂ O ₃ , using the following conditions (a) degreasing treatment and (b) etching treatment, the first step according to the present invention The fifth step was carried out under the following conditions (c) to (c) and order to prepare a ceramic wiring board having high-density wiring. The obtained ceramics wiring board had low resistance and good adhesion, and also had excellent etching properties during wiring formation, and desired fine wiring patterns were formed on the substrate at high density. .

Needless to say, the following treatment may include treatment such as washing and drying, if necessary, as in the conventional method.

(A) Degreasing treatment Methyl alcohol Conditions: room temperature 5 minutes (b) Etching treatment Etching solution composition: ammonium acid fluoride 100g / l sodium chloride 100g / l Conditions: 60 ° C 15 minutes First step (c) Sensitization treatment Senshi Titing solution composition: stannous chloride 0.05g / l Condition: 25 ℃ for 5 minutes (d) Activation treatment Activation solution composition: Palladium chloride 0.10g / l Condition: 25 ℃ for 5 minutes (e) Electroless nickel plating treatment Nickel Plating solution composition: (Nickel-phosphorus system) Nickel sulfate 0.01mol / l Sodium hypophosphite 0.04mol / l Trisodium citrate 0.02mol / l Conditions: 75 ℃ 15 minutes Second step (f) Acid activation treatment Activity Liquid composition: Sulfuric acid 10% Condition: Room temperature 1 minute (g) Electrolytic copper plating treatment Copper plating bath composition: Copper sulfate 70g / l Sulfuric acid 170g / l Brightener 5cc / l Condition: 23 ℃ 30-60 minutes 2A / dm ² No. Three steps (h) Pattern printing process Use solar ink Co. KB-30 as Sutoinku, which was silk screen printing on the second step to end the ceramic substrate to form a resist pattern by curing at 100 ° C. 10 min.

Fourth step (i) Etching treatment Etching solution composition: Phosphoric acid 500 ml / l Nitric acid 250 ml / l Conditions: 50 ° C for 4 seconds (nu) Resist removal treatment The resist was removed by immersing it in trichlene.

Fifth Step (L) Heat Treatment 250 ° C. in Air for 2 Hours Table 1 shows the performance of the ceramic wiring boards formed in this example. In addition, as a comparative example, the fifth step in the present example is omitted as Comparative Example 1, and the heat treatment of the fifth step is performed between the second step and the third step. The performance of the ceramic wiring boards obtained in Comparative Examples 1 and 2 is the same as that of Comparative Example 2
Shown in the table.

The adhesion strength test methods shown in Table 1 are as follows.

(1) Form a 2 mm x 2 mm land as a measurement land.

(2) A tin-plated copper wire with a diameter of 0.6 mm is placed in the center of the measurement land in a direction perpendicular to the substrate and soldered with a soldering iron at 260 ± 10 ° C within 5 seconds and washed with trichlene.

(3) Put the soldered sample in a constant temperature bath of 150 ± 10 ℃.
Store for 2 hours.

(4) Pull the dried sample with a tensile tester in the direction perpendicular to the substrate, and measure the value when the conductor part peels off.
Adhesion strength.

Example 2 A ceramic wiring board was manufactured in the same manner as in Example 1 except that the electrolytic copper plating treatment in the second step in Example 1 was replaced with the following electroless copper plating.

Second step Electroless copper plating treatment Electroless copper plating bath composition: EDTA Copper 1g / l (as copper) EDTA 40g / l Paraformaldehyde 7g / l α-α'dipyridyl 10ppm Conditions 60 ℃ 2 hours pH12 Ceramics obtained The wiring board is easy to etch, electroless Ni plating 0.2μm, electrolytic Cu plating 5.2μm,
It showed good performance with conductor resistance of 3 mm / □ and adhesion strength of 9.5 kg / 2 mm x 2 mm.

〔The invention's effect〕

As described above, according to the present invention, the problems in the conventional method for manufacturing a ceramic wiring board are solved, and low-density high-density wiring can be manufactured at low cost and with high performance.

Claims (1)

[Claims] 1. A first step of: (1) subjecting a ceramics substrate to electroless nickel plating and laminating a nickel layer on the substrate; and (2) a ceramics substrate on which the nickel layer is laminated,
A second step of performing electroless copper plating and / or electrolytic copper plating and laminating a copper layer on the nickel layer of the substrate; and (3) the nickel of a ceramic substrate in which the nickel layer and the copper layer are sequentially laminated. And a third step of laminating a resist layer on a portion where the copper layer and the copper layer remain, and (4) etching the ceramic substrate on which the nickel layer, the copper layer and the resist layer are sequentially laminated to laminate the resist layer. Wiring formed by removing the nickel layer and the copper layer on the substrate other than the existing portions and then removing the resist layer to leave the nickel layer and the copper layer in the portion where the resist layer was laminated. And a fifth step of subjecting the ceramic substrate on which the wiring is formed to a heat treatment, and a fifth step of subjecting the ceramic substrate on which the wiring is formed to a heat treatment.