JP2000216536A - Manufacture of laminate board with inner layer circuits - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the CCD recognition by heating and holding a substrate over a specified substrate surface temp. for several seconds or more and adhering a Cu circuit with a thermosetting resin. SOLUTION: A Cu circuit on the surface of a substrate is treated with an acid water soln. contg. carboxylic acid, Cu ions and a Cu ion chelating agent to rough the Cu circuit surface, the rough-surfaced Cu circuit is washed with water, the substrate is heated and the substrate surface temp. held at 110 deg.C or higher for 5 sec or more, the Cu circuit is adhered with a thermosetting resin such as epoxy resins, phenol resins, polyimide resins, unsat. polyester resins and polyphenylene ether resins to produce. Thus it is possible to obtain an inner-circuit-contg. laminate board superior in acid resistance and solder heat resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a laminated board containing an inner circuit used for manufacturing a multilayer printed wiring board.

[0002]

2. Description of the Related Art A multilayer printed wiring board used for electric and electronic equipment is used to form a copper circuit by etching a copper foil on the surface of an inner layer substrate and then increase the adhesive strength to the copper circuit. Perform surface treatment, then laminate the substrate for the inner layer and the prepreg manufactured by impregnating the glass cloth with the thermosetting resin, further laminate copper foil on the outside of the laminate, heat and pressure mold To produce a laminated board with an inner circuit. Next, after drilling a hole in the inner layer circuit-containing laminate, a plating process is performed to form a through-hole plating film for conducting the inner layer copper circuit and the outer layer copper foil in the hole, and then the outer layer copper foil is etched. After forming an outer layer circuit by soldering, a solder resist film is formed on the surface of the laminated board other than the outer layer circuit to be connected to the electronic component so that solder does not adhere.

As a surface treatment applied to a copper circuit on the surface of the inner layer substrate, a chemical oxidation treatment called a blackening treatment is generally performed. However, when using the laminated board with the inner layer circuit that has been subjected to this blackening treatment, the acid such as the plating solution used in the plating process dissolves the treatment film around the hole, and the black color changes to pink, There is a problem that a phenomenon called haloing may occur in the obtained printed wiring board.

[0004] Therefore, a method of roughening a copper foil with a solution containing an acid, hydrogen peroxide and copper ions without performing an oxidation treatment, or a method of chelating acid, copper ions and copper ions without performing an oxidation treatment. A surface treatment method for giving a proper adhesive strength while suppressing the occurrence of haloing by a method of roughening a copper foil with a solution containing an agent or the like has been studied (for example, Japanese Patent Application Laid-Open No. 10-335815).

[0005] However, when roughening treatment is performed with such a solution containing copper ions, there is a problem that the solder heat resistance of the obtained laminated board with an inner layer circuit may be reduced, and there is room for improvement. . Therefore, there is a demand for a manufacturing method that can provide a laminated board with an inner layer circuit having excellent acid resistance and excellent solder heat resistance without performing an oxidation treatment.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to make a copper circuit formed on the surface of a substrate contain copper ions. After the surface of the copper circuit is roughened by treating with an acidic aqueous solution, a method of manufacturing a laminated board containing an inner layer circuit manufactured by bonding the roughened copper circuit and a thermosetting resin, and having excellent acid resistance. Another object of the present invention is to provide a manufacturing method capable of obtaining a laminate having an inner circuit having excellent solder heat resistance.

[0007]

According to the present invention, there is provided a method of manufacturing a laminated board having an inner layer circuit, wherein a copper circuit formed on a surface of a substrate is treated with an acidic aqueous solution containing copper ions to form a surface of the copper circuit. After the roughening, the method of bonding the roughened copper circuit and the thermosetting resin is performed by bonding the roughened copper circuit and the thermosetting resin. After roughening the surface of the copper circuit by
The surface of the roughened copper circuit is rinsed with water, and then the substrate is heated. After maintaining the surface temperature of the substrate at 110 ° C. or higher for 5 seconds or longer, the copper circuit is bonded to the thermosetting resin. There is a feature.

[0008] The method of heating the substrate is preferably a method of irradiating the surface of the substrate with infrared rays, and the thermosetting resin adhered to the copper circuit is a thermosetting resin impregnated in glass cloth. preferable.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for manufacturing a laminated board with an inner layer circuit according to the present invention, a copper circuit formed on the surface of an inner layer substrate is treated with an acidic aqueous solution containing copper ions to form a surface of the copper circuit. This is a method for manufacturing a laminated board with an inner circuit, which is manufactured by bonding a roughened copper circuit and a thermosetting resin after roughening.

The acidic aqueous solution used in the present invention is an acidic aqueous solution containing at least an acid and copper ions.
Liquid containing carboxylic acid and copper ions, carboxylic acid,
An acidic aqueous solution such as a solution containing copper ions and a chelating agent for copper ions and a solution containing sulfuric acid, hydrogen peroxide and copper ions, which can etch copper to roughen the surface of a copper circuit. If this acidic aqueous solution contains copper ions,
Since the etching amount is stable, the difference in the degree of roughening depending on the in-plane position of the substrate is reduced.

It is preferable that the acidic aqueous solution contains a carboxylic acid having 1 to 5 carbon atoms, such as formic acid or acetic acid, because the reactivity for roughening is excellent and the processing time can be shortened. Further, it is preferable that the acidic aqueous solution contains a chelating agent for copper ions, because the difference in the degree of roughening depending on the in-plane position of the substrate becomes small. This is thought to be because the presence of the chelating agent facilitates the dissolution of copper on the surface of the copper circuit, and the roughening proceeds uniformly. Examples of the chelating agent include ethylenediaminetetraacetic acid, cyclohexanediaminetetraacetic acid, 1,10-phenanthroline, 8-hydroxyquinoline and the like.

When the surface of a copper circuit is roughened using an acidic aqueous solution containing a carboxylic acid and copper ions, the concentration of the carboxylic acid is generally from 10 to 100 g / L (hereinafter referred to as g / L). Desirably, the concentration of copper ions is desirably 15 to 25 g / L. Also,
The pH is desirably 4 or less, and the liquid temperature during the treatment is desirably about 30 to 45 ° C.

When the surface of a copper circuit is roughened using an acidic aqueous solution containing carboxylic acid, copper ions and a chelating agent for copper ions, the concentration of the carboxylic acid is generally 10%.
The concentration of copper ions is preferably 15 to 25 g / L, and the concentration of the chelating agent for copper ions is desirably 0.1 to 10 g / L. Further, the pH is desirably 4 or less, and the liquid temperature during the treatment is desirably 30 to 45 ° C.

When the surface of a copper circuit is roughened using an acidic aqueous solution containing sulfuric acid, hydrogen peroxide and copper ions, the concentration of sulfuric acid is generally desirably 30 to 150 g / L. The concentration of hydrogen oxide is generally 5 to 5
0 g / L, and the concentration of copper ions is 5 g / L.
３０30 g / L, and the liquid temperature during the treatment is
25-45 ° C is desirable.

The treatment time using the acidic aqueous solution is appropriately determined according to the composition and temperature of the acidic aqueous solution, but it is preferable to perform the treatment under the condition that the surface roughness of the copper circuit is 2 to 6 μm. When the thickness is less than 2 μm, the adhesiveness of the obtained laminate may decrease. When the thickness exceeds 6 μm, the thickness of the copper circuit may be reduced and the electrical reliability may decrease.
Examples of the method of treating the copper circuit with an acidic aqueous solution include a method of spraying the copper circuit with an acidic aqueous solution and a method of immersing the copper circuit in an acidic aqueous solution.

The acidic aqueous solution may contain a humectant, a rust inhibitor and the like. Before the treatment with the acidic aqueous solution, if necessary, the surface of the copper circuit may be washed by mechanical polishing or chemical polishing such as ammonium persulfate, and then the treatment may be performed with the acidic aqueous solution.

Next, the copper circuit roughened by the treatment with the acidic aqueous solution is washed with water to remove the acidic aqueous solution adhering to the surface, and then the substrate is heated to dry the moisture. A laminated board with an inner layer circuit is manufactured by bonding a curable resin.

It is important that the substrate is heated so that the surface temperature of the substrate is kept at 110 ° C. or more for 5 seconds or more. By this heating, the moisture absorbed by the substrate when treated with the acidic aqueous solution is dried, and the resulting laminated board with an inner layer circuit becomes a laminated board with an inner layer circuit having excellent solder heat resistance. In addition, 110 ° C
If the above temperature is less than 5 seconds or if the surface temperature of the substrate does not reach 110 ° C., the dehumidification is insufficient, and the solder heat resistance of the obtained laminated board with an inner layer circuit is reduced.

The surface temperature of the substrate is a temperature measured at the surface of the copper circuit. If the holding time at a temperature of 110 ° C. or more differs depending on the in-plane position of the substrate, even at the shortest position. Heat to hold for more than 5 seconds. Further, the upper limit time of the state in which the surface temperature of the substrate becomes 110 ° C. or more is not particularly limited,
Less than 10 minutes is economical.

The method of the heat treatment is not particularly limited as long as the surface temperature of the substrate can reach 110 ° C. or higher, and a method of blowing hot air onto the surface of the substrate, an infrared ray on the surface of the substrate, And the like. In the case of the method of irradiating the surface of the substrate with infrared rays,
It is preferable because the surface temperature of the substrate can easily reach 110 ° C. or higher.

The thermosetting resin used in the present invention may be an epoxy resin, a phenol resin, a polyimide resin, an unsaturated polyester resin, a polyphenylene ether resin, etc., alone, modified, or a mixture. All thermosetting resins can be used.

In the case where the thermosetting resin is a thermosetting resin impregnated into a resin-impregnated base material generally called a prepreg, which is produced by impregnating a base material such as glass cloth with the thermosetting resin, the adhesive property and the The effect of improving the acid resistance is large and preferable, but it is not limited to the thermosetting resin used for the prepreg, and the metal foil is bonded to the surface of the inner layer substrate via the thermosetting resin layer without the base material. A thermosetting resin for forming a resin layer or a thermosetting resin for forming a solder resist film used in a method generally called a build-up method may be used.

The substrate for the inner layer used in the present invention may be a plate having a copper circuit formed on one or both sides using a material that can withstand heat treatment for curing the thermosetting resin. For example, the above-mentioned thermosetting resin sheet is a plate in which copper foil is stretched on one or both sides, a cloth of inorganic fibers such as glass or an organic fiber such as polyimide, a substrate such as paper, and the above-mentioned thermosetting resin. Adhering with resin, using a board or the like with copper foil on one or both sides, etching the copper foil to form a circuit, or performing copper plating on the surface of the board without copper foil And those formed with a copper circuit.

[0024]

(Example 1) A glass-based epoxy resin double-sided copper-clad laminate having a size of 50 × 50 cm and a thickness of 0.8 mm excluding copper foil [trade name: R-176, manufactured by Matsushita Electric Works, Ltd.]
6] is etched to form a plurality of land patterns having a diameter of 1.5 mm and a size of 30 × 10
An inner layer substrate having a pattern in which 0 mm copper foil remains was obtained.

Also, as an acidic aqueous solution containing a carboxylic acid having 1 to 5 carbon atoms and a chelating agent for copper ions, a copper hydroxide is dissolved by using a treatment liquid [trade name: CZ8100] manufactured by Mec Co., Ltd. An acidic aqueous solution having a pH of 3.5 and containing 15 g / L of the ions was bathed. The copper ion concentration was determined by sampling an acidic aqueous solution,
It measured by titrating using A (ethylenediaminetetraacetic acid) normal liquid.

Then, the copper circuit was contacted with the acidic aqueous solution for 165 seconds by spraying an acidic aqueous solution whose temperature was controlled at 38 ° C. onto the copper circuit, thereby roughening the surface of the copper circuit.
Next, after washing with water to remove the acidic aqueous solution adhering to the surface, hot air was blown onto the surface of the substrate to heat the substrate so that the surface temperature of the substrate was kept at 110 ° C. or higher for 5 seconds.

Next, a thickness of 0.15
mm, a glass-based epoxy resin prepreg having a resin amount of 50% [trade name: R-1661, manufactured by Matsushita Electric Works, Ltd.] is laminated on both sides of the inner layer substrate by two sheets, and further, both outer layers of the laminate are laminated. Then, a copper foil having a thickness of 18 μm was laminated thereon, and this laminate was heated and pressed under the conditions of a temperature of 170 ° C., a pressure of 3.9 MPa, and a time of 60 minutes to obtain a laminate having an inner layer circuit.

Example 2 After washing with water to remove the acidic aqueous solution adhering to the surface, the surface of the substrate is irradiated with infrared rays so that the surface temperature of the substrate is kept at 110 ° C. or higher for 5 seconds. Except that heating was performed in the same manner as in Example 1, a method for producing a laminated board with an inner layer circuit was obtained.

Example 3 After washing with water to remove the acidic aqueous solution adhering to the surface, the surface of the substrate is irradiated with infrared rays so that the surface temperature of the substrate is kept at 110 ° C. or higher for 15 seconds. Except that heating was performed in the same manner as in Example 1, a method for producing a laminated board with an inner layer circuit was obtained.

(Comparative Example 1) After washing with water to remove the acidic aqueous solution adhering to the surface, the surface of the substrate is irradiated with infrared rays so that the surface temperature of the substrate is kept at 110 ° C or higher for 1 second. Except that heating was performed in the same manner as in Example 1, a method for producing a laminated board with an inner layer circuit was obtained.

Comparative Example 2 A method for producing a laminated board with an inner circuit was obtained in the same manner as in Example 1 except that the substrate was heated so that the surface temperature of the substrate was kept at 110 ° C. or higher for 4 seconds.

(Comparative Example 3) After washing with water to remove the acidic aqueous solution adhering to the surface, the surface of the substrate is irradiated with infrared rays so that the surface temperature of the substrate is kept at 110 ° C or higher for 4 seconds. Except that heating was performed in the same manner as in Example 1, a method for producing a laminated board with an inner layer circuit was obtained.

(Evaluation and Results) The heat resistance and the acid resistance of the laminates with the inner layer circuits obtained in each of the examples and comparative examples were measured.

The solder heat resistance was evaluated by preparing an evaluation sample by etching the entire surface of the copper foil of the outer layer of the laminated board with the inner layer circuit, cutting it into a square of 50 mm, and then polishing the end face.
Next, the evaluation sample was placed in ion-exchanged water for 1 hour or 2 hours.
After boiling for 3 hours or 3 hours.
It was immersed for 0 seconds and visually observed for abnormalities such as measling. Then, when no abnormality such as measling or delamination occurred, it was evaluated as ○, and when an abnormality such as measling or delamination occurred, it was evaluated as x.

The acid resistance is measured by using a 0.4 mm diameter drill [manufactured by Union Tool Co., Ltd., product name: UC30] at a position where a land pattern with a diameter of 1.5 mm of the inner layer substrate is located in the laminated board containing the inner layer circuit. 50 holes were drilled at a rotation speed of 72,000 rpm and a feed rate of 19 μm / rotation, then immersed in a 1.2 N hydrochloric acid aqueous solution at 20 ° C. for 10 minutes, washed immediately, and then washed with an outer layer. The copper circuit of the inner layer substrate is exposed by shaving the insulating layer where the copper foil and prepreg have hardened, and the maximum length from the wall surface of the hole of the part where the treated film has turned pink is magnified by 50 times. It was measured.

The results are shown in Table 1. As shown in Table 1, the laminated board with the inner layer circuit obtained in each of the examples has better solder heat resistance than the laminated board with the inner layer circuit obtained in each of the comparative examples, and It was confirmed that the laminate had excellent acid resistance, similarly to the laminate with the inner layer circuit obtained in each comparative example.

[0037]

[Table 1]

[0038]

According to the method of manufacturing a laminated board with an inner layer circuit according to the present invention, after roughening the surface of a copper circuit, the surface of the roughened copper circuit is washed with water, and then the substrate is heated. After maintaining the surface temperature of 110 ° C. or more for 5 seconds or more, the copper circuit and the thermosetting resin are bonded together to produce, so that the laminated board with the inner layer circuit having excellent acid resistance and solder heat resistance is excellent. It is possible to obtain.

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Claims (3)

[Claims] 1. A copper circuit formed on a surface of a substrate is treated with an acidic aqueous solution containing copper ions to roughen the surface of the copper circuit, and then the roughened copper circuit is bonded to a thermosetting resin. In the method for manufacturing a laminated board with an inner layer circuit to be manufactured, the method of bonding the roughened copper circuit and the thermosetting resin is performed after the surface of the copper circuit is roughened by treating with an acidic aqueous solution. The method is characterized in that the surface of the copper circuit is washed with water, then the substrate is heated, and the surface temperature of the substrate is kept at 110 ° C. or more for 5 seconds or more, and then the copper circuit and the thermosetting resin are bonded. A method for producing a laminated board containing an inner circuit. 2. The method according to claim 1, wherein the method of heating the substrate is a method of irradiating infrared rays to the surface of the substrate. 3. The method according to claim 1, wherein the thermosetting resin that adheres to the copper circuit is a thermosetting resin impregnated in a glass cloth. .