DE2044484A1 - Adhesion promoter for the production of printed circuits according to the build-up method - Google Patents

Description

Standard Elektrik Lorenz AG ^ ^

Stuttgart

H. Schmid - 1

Adhesion promoter for the production of printed circuits according to the Rearing method.

The application relates to the manufacture of printed circuit boards according to the known build-up method. In this known method, a non-laminated insulating plate assumed, if necessary is already provided with holes, if the insulating plate is on both sides to be versJien with conductor tracks and those arranged on both sides Conductor tracks are to be plated through.

In the known method (ER-PS 1 519 797) the mechanically and / or chemically roughened entire insulating material plate is provided with an adhesive or bonding agent layer. After the adhesion promoter with tin and palladium has been activated, is then applied to the entire one insulating plate by chemical copper plating about 0.5 to 1 Am thick copper layer then to about j5 to 5 / To is amplified by galvanic plating. Instead of galvanically reinforcing the 0.5 - l / µm thick copper layer, the entire copper layer of 3 - 5 / µm can be built up chemically.

This generated in a known manner copper base layer, a negative mask is applied to the provided to the copper base layer insulating plate in a likewise known manner in the screen printing or by a photo method which allows only the future tracks uncovered * on these surfaces is then the copper base layer by electrolytic copper plating to about 35 / Xn reinforced. The undesired parts of the copper base layer are finally etched away in such a way that, after the negative stencil has been removed, the entire plate is exposed to an etching liquid, which means that, in addition to the thin copper base layer, the conductor tracks are also etched away to a correspondingly small thickness.

9/8/1970

Gust / thu - / -

209811/150?

L U

H. Sohmid - 1

Although it is also already known as a natural or adhesion promoter using synthetic rubbers, it has not yet been possible to to find an adhesion promoter with which the required adhesive strength of the copper on the insulating plate can be achieved. In addition to sufficient adhesive strength of the conductor tracks, further strict requirements are placed on printed circuits, such as high ones Resistance to solder baths, resistance to acids and alkalis, stamping and Drilling ability and high surface resistance, which with the well-known Adhesion promoters could only be realized to a limited extent or with increased scrap.

The task of the application is therefore to provide a new, improved adhesion promoter " ler for the manufacture of printed circuits to indicate without the construction method, in which the adhesion between the insulating material plate and the copper base layer takes place exclusively through the adhesion promoter.

According to the invention, the adhesion promoter consists of

40-60% by weight acrylonitrile

30-35 wt % butadiene

5-10% by weight of phenolic resin dissolved in methyl ethyl ketone.

Particularly advantageous has proven in the production of printed circuits according to the growing method, an adhesion promoter, which according to one preferred embodiment of the invention% from

1000 g of acrylonitrile butadiene solution

36 g phenolic resin and
360 g of methyl ethyl ketone
consists.

209811/1507

H. Schmid - 1.

In addition to other excellent properties, this adhesion promoter is characterized by its ability to dry quickly and the insulating panels coated with it are extremely stackable due to their impact and scratch resistance. Moreover, the activatable adhesive layer on an insulating plate in a known manner, for example with a mixture of 50 wt% sulfuric acid, 50 wt% water and 6og / l of chromic acid in a simple manner without destroying the matrix, ie anätzbar.

The new adhesion promoter, which requires a drying time of around 2.5 hours at 140 G, also has a surface resistance of 10 to 10 M _- Q. depending on the activation strength. Printed circuits produced with the new bonding agent using the build-up method have a solder bath resistance of 45 + 5 seconds at the soldering temperature of 260 ° C required by the DIN standard. While the bonding agent is otherwise resistant up to 160 C, the conductor tracks attached to printed circuits with it have an adhesive strength of 6-10 kg / 25mm. Furthermore, it can be used equally well in connection with phenolic resin laminates and epoxy resin laminates and has good resistance to dilute acids and alkalis.

The beneficial effect of the new adhesion promoter is presumably based on that when activated, the butadiene component is attacked more rapidly by oxidation is considered the other two components. This allows in the adhesion promoter layer At the points where a butadiene chain is located, a molecular hole is created in which the later chemically deposited copper is anchored. The phenolic resin component, which at the same time has a good affinity for Has base material, gives the adhesion promoter the excellent temperature resistance.

2 claims

V-20 9811/150 7

Claims (2)

H. Schmid - 1 claims ! 1. an adhesion promoter for the production of printed circuits according to the construction method, characterized in that the adhesion promoter is from 40 - 60 wt% of acrylonitrile
30-35 wt % butadiene 5-10% by weight of phenol resin
that are dissolved in methyl ethyl ketone. 2. Adhesion promoter according to claim 1, characterized in that the adhesion promoter from 1000 g acrylonitrile butadiene solution 36 g phenolic resin and
360 g of methyl ethyl ketone
consists. 209811/1507