JPS61241329A - Method of bonding copper and resin - Google Patents

Abstract

PURPOSE:To obtain a patch board, etc., having high adhesivity free from corrosion with acids, by forming a copper oxide layer on the surface of copper, reducing the layer into metallic copper with a reducing solution, forming further a copper oxide layer with an acidic solution and bonding a resin to the layer by contact bonding under heating. CONSTITUTION:In bonding copper to a resin by contact bonding under heating, a copper oxide layer is formed on the surface of copper, the layer is treated with a reducing solution so that the copper oxide layer is reduced into metallic copper, while is treated with an oxidizing to form a copper oxide layer and the bonding is carried out.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method of adhering copper and resin, and is particularly suitable for manufacturing a multilayer printed wiring board formed by laminating and adhering a copper circuit layer and a resin layer. This article relates to a method of adhering copper and resin.

[Background of the invention]

When adhering copper and resin, it is not possible to obtain sufficient adhesion force by adhering the copper surface as it is.
CUITS MANUFACTURING), J
A method of forming an oxide layer on the copper surface as described in AN1985, P 64-65Vc, or a method of reducing the copper compound layer to metallic copper using a reducing solution after forming the oxide has been reported. However, in the method of forming the copper oxide layer, the copper oxide layer is hydrolyzed in an acidic aqueous solution and dissolved as copper ions.

Furthermore, although the method of reducing metal copper has an extremely excellent effect on acid resistance, the chemical affinity with the resin is impaired, resulting in lower adhesion strength compared to oxidation treatment. If such a method is applied to future high-density and highly multilayer printed wiring boards, the problem will arise that the copper layer will peel off from the resin layer due to heat due to insufficient adhesive strength.

[Purpose of the invention]

An object of the present invention is to provide a method for adhering copper and resin, which has good acid resistance and sufficiently high adhesion.

[Summary of the invention]

Conventionally, various methods have been studied as methods for pre-treating copper for adhesion between copper and resin.

For example, in multilayer printed wiring boards, the steel surface to be bonded is treated with an alkaline aqueous solution containing sodium chlorite to improve adhesive strength, and
There is a method of forming a cupric oxide layer. This method of forming a copper oxide layer is extremely effective for improving adhesive strength, but generally, in order to improve adhesive strength, the copper oxide layer must be formed thickly. Further, when the copper oxide layer comes into contact with acid, it is hydrolyzed and dissolved. From the above two points, the acid treatment process after bonding causes the undesirable phenomenon that the oxide layer at the bonding interface exposed on the inner surface of the hole penetrating the bonding surface or the edge of the cut surface dissolves, causing acid to seep into the interface. . Further, as a means for preventing acid seepage, there is a method in which, after performing the above-mentioned oxide layer formation treatment, reduction treatment is performed in a reducing solution containing dimethylborane amine or the like to form metallic copper.

However, although the adhesion between metallic copper and resin obtained in this way is extremely effective against acid seepage, the chemical affinity with the resin is impaired, so the above-mentioned oxidized steel layer is formed. The adhesion strength is lower than that of other materials. Therefore, when this method is applied to a multilayer printed wiring board, there is a problem in that the metal copper and the resin at the bonding interface peel off due to heat treatment after bonding.

The present invention addresses this problem by forming a copper oxide layer on the steel surface and applying a reducing solution to the formed copper oxide layer to reduce the copper oxide layer to metallic copper. The present invention is characterized by a method for adhering copper and resin, including a step of applying an oxidizing solution to the core metal copper layer to form a copper oxide layer.

[Embodiments of the invention]

The present invention will be explained below by taking lamination adhesion of a multilayer printed wiring board as an example.

Example 1 (1) The copper surface of a glass cloth-filled polyimide resin steel-clad laminate was coated with 0 words C4 H2O50f/LHC1 (56%).
Etching is carried out by immersing it in an aqueous solution at a temperature of 500 f/40 for 1 minute.

(2) Next, after washing with water, the temperature of NaCLCb 90 f/L NaOH509/1 NasPOa-t2Hto 15t/
Treat with 75υ aqueous solution for 1 minute to form a copper oxide layer on the surface.

(5) After washing with water Dimethylamine borane 6f/L NaOH5f/L Temperature 256 The oxide layer is reduced by leaving it in an aqueous solution of for 1 minute.

(4) Next, after washing with water, NaCtO250t/1 NaOH+ Ot/L NasPOa ・12 H2O5f/L temperature
A thin copper oxide layer is formed on the surface by evacuating the sample in a 75 V aqueous solution for 50 seconds.

(After washing the copper-clad laminates treated as above in 51 with water and drying them, they were laminated through a prepreg made of glass cloth impregnated with polyimide resin, and bonded by applying pressure at 170°C for 80 minutes at 20 intervals. .

(6) The adhesion between the copper foil laminated and bonded in this way and the polyimide resin of the prepreg layer was good, and the beer strength was 1.4 Kv'c111. Further, after multi-layer adhesion, a through-hole was made and immersed in 1:1 hydrochloric acid, but no acid seepage from the through-hole wall or discoloration of the adhesive interface layer was observed even after immersion for more than 5 hours.

Example (1) The treatments (1) to (4) of Example I were also carried out on a glass cloth-containing epoxy resin copper-clad laminate.

(2) Next, after washing with water and drying, the glass cloth is laminated with prepreg impregnated with epoxy resin, and 1
A pressure of 4/cII was applied to 20 for 60 minutes at 70υ to bond.

(5) Next is an example! The same evaluation as in (6) was conducted.

As a result, beer strength was 2.8 kg/an and acid resistance was 5.
It was good for more than an hour.

Example I Actual multilayer printed wiring boards were prepared and evaluated according to Examples (1) and (2), and good results were obtained in both hydrochloric acid penetration and heat resistance.

Comparative example! The glass cloth-containing polyimide resin copper-clad laminates treated in Example I (1) and (2) were adhered in the same manner as in Example I (5), and beer strength and hydrochloric acid resistance were evaluated.

As a result, the beer strength was 1.4 degrees, but it was found that acid seepage occurred within 5 minutes after immersion in 1=1 hydrochloric acid @ Comparative Example Glass cloth filled epoxy resin steel clad laminate The plate was also evaluated in the same way as the comparative example, and the beer strength was 2-8 hours.
/cryt, but regarding hydrochloric acid resistance, acid seepage occurred within 5 minutes.

Comparative Example■ Glass cloth-containing polyimide resin steel-clad laminates treated in (1) to (5) of Example I were adhered in the same manner as in (5) of Example I, and beer strength and hydrochloric acid resistance were evaluated. did.

As a result, the hydrochloric acid resistance was good at 5 hours or more, but the beer strength was 1.0 to 12 b/es.

In addition, an epoxy resin steel-clad laminate containing glass cloth was evaluated in the same manner, and the results were similar to those of the polyimide resin steel-clad laminate containing glass cloth.

〔Effect of the invention〕

As described above, according to the present invention, copper and resin can be bonded to each other without being attacked by acids and having high adhesion strength.

Claims (1)

[Claims] In the method of bonding copper and resin by heat-pressing, there are two steps: forming a copper oxide layer on the copper surface, and applying a reducing solution to the formed copper oxide layer to convert the copper oxide layer into metallic copper. A method for adhering copper and resin, comprising the steps of reducing the metal copper layer and further applying an oxidizing solution to the metal copper layer to form a copper oxide layer.