DD159592A1 - METHOD FOR PRODUCING CONDUCTOR PLATES - Google Patents

Abstract

The invention relates to a method for the production of printed circuit boards with high resistance to thermal cycling, in particular with high Lötbadbeständigkeit. An inorganic carrier material, in particular a glass fiber substance, or a polymer is treated with an aqueous organo-functionalized silica sol having an average particle size of the organofunctionalized colloidal SiO 2 particles in the silica sol of 5 to 40 nm. As a result of this treatment, delamination phenomena of the guide plate are avoided and the reject rate is lowered.

Description

Process for the production of printed circuit boards

Field of application of the invention

Process for the production of printed circuit boards with high resistance to thermal cycling, in particular with high solder bath resistance.

Characteristic of the known technical solutions

Processes for the impregnation of support materials are known in which they are treated with:

water-soluble phenolic resins containing amino or epoxy silane (DE-AS 2 410 409),

Solvent-free binders, wherein the impregnation process by vacuum, ultrasound or heating (DD-PS 133 513) is supported,

- Special epoxy resin / hardener systems (DE-AS 2,033,626, US-PS 4,075,260, DE-OS 2,308,433 and 2,559,417).

It is also known to cure a laminate of a methacrylic acid-chromium complex-treated glass silk fabric and epoxy resin under pressure until gelation, followed by further curing under reduced pressure (US Pat. No. 3,660,199). It is also known to use a nonwoven made of a mixture of aromatic polyamide fiber and polyester fiber as support material (DE-OS 2,134,668).

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These known methods have the disadvantage that, although the resistance to hot water and solvent treatments is increased, however, delamination phenomena occur during thermal cycling , eg in the so-called "stress test". Furthermore, the use of special resin / harder systems is economically very expensive.

Object of the invention

It is the object of the invention to avoid Delaminierungserscheinungen and thus to reduce the reject rate.

DESCRIPTION OF THE INVENTION OF THE INVENTION Technical Problem

The invention has for its object to produce resistant to thermal cycling PCBs by modifying the boundary layer between the inorganic support material and the polymer.

Features of the invention

According to the invention, the object is achieved by treating an inorganic support material or a polymer with an aqueous organofunctionalized silica sol having an average particle size of the organofunctionalized colloidal SiO 2 particles in the silica sol of from 5 to 40 nm. It is advantageous to treat the support material or the polymer with an aqueous silica sol to which organofunctional silanes and / or Werner-type organic unsaturated acids chromium complexes have been added. The organofunctional silanes used are epoxysilanes, aminosilanes, methacrylsilanes or their mixtures, as chromium complexes of organic unsaturated acids chromium chloride methacrylate.

In the addition of organofunctional silanes and / or chromium complexes of Werner-type organic unsaturated acids

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to the aqueous silica sol, the organic compounds are adsorbed by the SiO 2 particles and a chemical reaction occurs between the silanes or chromium complexes and the hydroxyl groups of the SiO 2 particles _; of silica sol. As a result of the deposition of the organofunctional SiO 2 particles on the surface of the support material as a result of the treatment of the inorganic support material or of the polymer, the boundary layer between the inorganic support material and the organic polymer is modified. As a result of this modification occur at thermal cycling, z. B. in the "stress test" no delamination phenomena ("measling") on. The carrier material used is in particular a sheet of glass fiber materials.

· Embodiment;

Below, the invention will be explained in more detail using an exemplary embodiment:

10 g of silica sol 30 -

60 gf -Glycidoxypropyltrimethoxysilane and

50 g f -Methacryloxypropyltrimethoxysilane

Y / earth mixed, made up to 10 1 with distilled water and stirred for 100 min. The pH of the solution is adjusted to 4 with formic acid. After completion of the reaction, a thermally desized glass fiber fabric having a surface density of 200 g / m is impregnated with this solution on a pad, squeezed to a residual moisture content of 33% between rollers and dried at 120 ⁰ C. The fabric thus treated is impregnated with an epoxy resin solution containing curing agent and accelerator, and pressed from the obtained prepreg plates in the usual manner (3 fabric layers). In thermal cycling, z. As in the "stress test" show no delamination phenomena ("heasling"), since the organofunktionalisierten SiOo particles in the boundary layer reduce the stresses arising on exposure to temperature.

Claims (4)

invention claim 1. A process for the production of printed circuit boards with high resistance to thermal cycling, especially high Lötbadbeständigkeit consisting of inorganic support material, preferably glass fibers, and polymers, characterized in that an inorganic support material or a polymer with an aqueous organofunktionalisierten silica sol having an average particle size of the organofunktionalisierten colloidal SiOp Teilehen in silica sol from 5 to 40 nm is treated. 2. The method according to item 1, characterized in that the inorganic support material with an aqueous silica sol, the organofunctional silanes and / or chromium complexes of organic unsaturated acids of Werner-type were added, is impregnated. 3. The method according to item 2, characterized in that are used as organofunctional silanes epoxysilanes, aminosilanes, methacrylsilanes or their mixtures. 4. The method according to item 2, characterized in that chromium chloride methacrylate is used as chromium complexes of organic unsaturated acids.