JPH0582941A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To provide the manufacture of a printed wiring board, in which the firm adhesion of an insulating substrate and a precipitated electroless plating layer is obtained, regarding the manufacture of the printed wiring board, in which a circuit is manufactured by a circuit forming process including electroless plating to a section, to which at least the circuit is formed. CONSTITUTION:In a roughening process as plating pretreatment, in which the resin layer of an insulating substrate is formed in a surface shape proper to plating, the resin layer is chemically roughened by a chromic acid- tetrafluoroboric acid aqueous solution containing fluorine ions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a printed wiring board in which a circuit is formed in a circuit forming step including electroless plating at least in a portion where a circuit is formed. It is intended to provide a method for producing a printed wiring board, which can obtain strong adhesion with an electrolytic plating layer.

[0002]

2. Description of the Related Art In recent years, as a method of manufacturing a printed wiring board, a method of forming a circuit in a circuit forming step including electroless plating at least in a portion where a circuit is formed (additive method) has been widely used. .. Additive law includes
After chemically roughening the insulating substrate, cover the portion where the circuit is not formed with the electroless plating resist, or coat the portion other than the portion where the circuit of the insulating substrate is formed with the electroless plating resist and then roughen it. Perform a method of forming a circuit by dipping it in an electroless plating solution (full additive method), and chemically roughen the insulating substrate, and then electrolessly plate the entire surface of the substrate except the part where the circuit is to be formed. A method (semi-additive method) of forming a layer, coating electroplating resist on the area other than the area where the circuit is formed, performing thick plating on the area of the circuit, and removing the electroless plating layer other than the area of the circuit by etching is performed. It is being appreciated.

In all of these methods, the insulating substrate is roughened and electroless plating is performed. Since the deposited plating firmly adheres to the resin layer, it is important to make the surface uneven. As a roughening liquid for roughening the surface as a pretreatment for plating, an oxidizing acid solution is generally used. For example, the examples of JP-A-63-199497 and JP-A-63-19839 are used.
The chromic acid-sulfuric acid aqueous solution or chromic acid-tetrafluoroboric acid aqueous solution of Example 4 of Example 5 is used.

[0004]

Problems to be Solved by the Invention JP-A-63-1994
97 and the chromic acid-sulfuric acid aqueous solution of Example 4 of JP-A-63-198395 make a good roughened shape, but inactivate the inside of the through holes, and prevent the deposition of electroless plating. Has a problem that it does not precipitate. or,
The chromic acid-tetrafluoroboric acid aqueous solution does not hinder the deposition of electroless plating, but is regulated to a composition that easily forms roughening irregularities (containing 50% by weight or more of diene-based synthetic rubber in the resin). In addition, a substrate containing a large amount of diene-based synthetic rubber in the resin is not preferable because it lowers the electrical characteristics, heat resistance or surface hardness of the printed wiring board, and it is desirable to reduce or not include the diene-based synthetic rubber. It is rare.

The present invention relates to a method for manufacturing a printed wiring board in which a circuit is formed in a circuit forming step including electroless plating at least in a portion where a circuit is formed, and a strong adhesion between an insulating substrate and a deposited electroless plating layer. It is an object of the present invention to provide a method for manufacturing a printed wiring board that can obtain the above.

[0006]

According to the present invention, a resin layer of an insulating substrate is chemically treated with a chromic acid-tetrafluoroboric acid aqueous solution containing a fluorine ion in a roughening step of a pretreatment for forming a surface uneven shape suitable for plating. It is characterized by roughening.

A chromic acid-tetrafluoroboric acid aqueous solution containing fluorine ions is a water-soluble fluoride capable of supplying fluorine ions to an aqueous solution of dichromate such as sodium dichromate or chromic anhydride and tetrafluoroboric acid. What was added can be used.

Hexavalent chromium ions have a concentration of 0.01-0.
A range of 2 mol / l can be used, preferably 0.5 to
The range of 0.15 mol / l is desirable. 0.01 mol
If it is less than 1 / l, the oxidizing power of the resin cannot be obtained, and 0.2
When it is more than 1 mol / l, it is difficult to dissolve chromium ions and there is a problem in working, so that it cannot be used. Tetrafluoroboric acid may be used in a concentration range of 30 to 60% by weight, preferably 40 to 50% by weight. At a concentration of 30% by weight or less, the oxidizing power of the resin cannot be obtained, and 60% by weight
Above is tetrafluoroboric acid is saturated and difficult to dissolve,
Hexavalent chromium ions and fluorine ions are difficult to dissolve and cannot be used. The concentration of fluorine ion is 0.01-
A range of 0.5 mol / l can be used, preferably 0.1
A range of up to 0.3 mol / l is desirable. 0.01 mol
If the concentration is less than 1 / l, the effect of increasing the oxidizing power of the resin cannot be obtained, and if it is more than 0.5 mol / l, plating deposition on the resin is hindered, and therefore it cannot be used.

[0009]

[Function] By supplying fluorine ions to the chromic acid-tetrafluoroboric acid aqueous solution, it is possible to increase the resin oxidizing power of chromic acid and form an uneven shape capable of obtaining firm adhesion with the deposited electroless plating layer. ..

[0010]

[Example] Example 1 Laminated plate with adhesive (Hitachi Chemical Co., Ltd. ACL-E-
168), an ultraviolet-curable plating resist (SR-3000 manufactured by Hitachi Chemical Co., Ltd.) was prepared on a portion of the insulating substrate other than the portion where the circuit is formed, and then sodium dichromate 20 g
/ L, sodium fluoride 10g / l are immersed in a roughening solution in which 42% tetrafluoroboric acid is dissolved at 40 ° C for 5 minutes for roughening treatment and neutralization treatment, followed by electroless copper plating (Hitachi Chemical A circuit having a conductor thickness of 30 μm was produced using L-59 manufactured by Kogyo Co., Ltd. The circuit board manufactured in this way is
As a result of measuring the peeling strength of the conductive circuit based on IS-C6481, it had a value of 2.0 to 2.2 N / cm.

When the surface and cross section of the roughened epoxy resin were observed with a scanning electron microscope, a uniform uneven shape having a depth of about 15 to 25 μm was formed.

Example 2 A laminated board with an adhesive (ACL-E- manufactured by Hitachi Chemical Co., Ltd.)
168) was immersed in a roughening solution prepared by dissolving 20 g / l of sodium dichromate and 10 g / l of sodium fluoride in 42% tetrafluoroboric acid at 40 ° C for 5 minutes for roughening treatment and neutralization treatment. An ultraviolet curable plating resist (SR-3000 manufactured by Hitachi Chemical Co., Ltd.) was prepared on a portion of the insulating substrate other than the portion where the circuit is formed, and electroless copper plating (L-59 manufactured by Hitachi Chemical Co., Ltd.) was used. A circuit having a conductor thickness of 30 μm was produced. The circuit board produced in this way is JIS-
As a result of measuring the peeling strength of the conductive circuit based on C6481, it had a value of 1.9 to 2.1 N / cm.

When the surface and cross section of the roughened epoxy resin were observed with a scanning electron microscope, a uniform uneven shape having a depth of about 15 to 25 μm was formed. The effect of the present invention is shown in Table 1 in comparison with the conventional method.

[0014]

[Table 1]

[0015]

As shown in the table, according to the present invention, the resin on the surface of the substrate can be formed with a sufficiently roughened and roughened shape, and strong adhesion can be obtained with the deposited electroless plating layer, which hinders the plating depositability. It is possible to obtain a method for manufacturing a printed wiring board that allows roughening without being performed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Chihisa 1500 Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Electronic Components Division

Claims (1)

[Claims] 1. A method for manufacturing a wiring board in which plating resist is applied, roughening, and electroless plating are performed on a laminated board with an adhesive to form a desired circuit, and the roughening step is to immerse the wiring board in an oxidizing aqueous solution. And the roughening liquid is 0.01 to
Hexavalent chromium ion of 0.2 mol / l, tetrafluoroboric acid of 30 to 60% by weight, 0.01 to 0.5 mol
A method for producing a printed wiring board, which comprises a fluorine ion of 1 / l.