DD148274A1 - METHOD FOR INCREASINGLY INCREASING CREEPING STREAM AND FLAME RESISTANCE - Google Patents

Abstract

The invention relates to a coating method for simultaneously increasing the creepage and flame resistance of electrical insulating parts, particularly printed circuit board base materials for use with increased safety requirements (e.g., marine equipment). The aim of the invention is insulating parts of electrical and electronic assemblies, in particular printed circuit boards of laminates in standard quality and from central manufacturing plants by subsequent coating with a suitable paint at the final producers for special conditions of use, i. The essentials of the invention is that the insulating parts at the same time in their creep u.Flammfestigkeit by coating (brushing, dipping, spraying) with a cold-curing, easily processable insulating material properties in the form of a paint or a Paste can be improved. As a suitable insulating material is a silicone rubber two-component paste type NG 3000 (with 8 to 10% crosslinker 112) of VEB Chemiewerk Nuenchritz, containing 5 to 10% of a flame-retardant mixture of tris-3-chloro-2-hydroxypropyl phosphate and antimony trioxide (Weight ratio 80:20) is modified, application. The application of the inventive solution can be done where electrical and electronic assemblies from standard production standards standard requirements do not meet u. must be modified by subsequent treatment for the specific conditions of use (for example in shipbuilding).

Description

applicants

Dr. Doz. Hans Schwarz, Wismar Prof. dr. Heinz Eaubach, Berlin Diploma Chemist Bernd Faik, Berlin

Authorized agent of the University of Applied Sciences Wismar Office for Reorganization and Property Rights

Title of the invention

Method for the simultaneous increase of leakage current and flame strength

Field of application of the invention

, The invention relates to a coating method for simultaneously increasing the creepage and fire resistance (reducing the inflammability) of electrical insulating parts, in particular of printed circuit boards (also equipped) for use conditions with increased security requirements (eg. The invention allows thus to modify electrical and electronic assemblies of standard standard production later for special conditions of use.

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Characteristic of the known technical solutions

To ensure the high electrical and mechanical Porderungen to a base material for printed circuits special Schwerentflairimbäre insulating materials z. For example, have been developed on epoxy resin 5basis with flame retardants, which meet the safety requirements for high fire resistance. As is known, such flame retardant laminates such as Aspasil and Glasil, which also have excellent tracking resistance, the electrical Anforderde Öläungen to a base material for printed circuit boards do not do justice. On the other hand, the flame retardant laminates based on epoxy and phenolic resin do not achieve the higher creep resistance required for special circuits because of the potential differences. On the other hand, have base materials

Of hydrocarbon resins having excellent creep resistance, high flammability.

It is further known that combustible building materials, e.g. Wood, already improved by a coat of fire-retardant substances in the fire resistance.

20This possibility of a subsequent improvement of the fire. Behavior of insulating arrangements is used in solid-insulated transformers for televisions by coating with a modified epoxy resin.

Furthermore, a method for increasing the creepage current 25 strength in synthetic resin laminates for high voltage equipment by the action of epoxidized fatty acid esters with curing agents on the surface is known.

The known prior art, however, always focuses only on the improvement of a property. Open is a simple 30Verfahren that subsequently allows simultaneously increase creepage and fire resistance.

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Object of the invention

The object of the invention is insulating parts of electrical and electronic assemblies, in particular printed circuit boards of laminates in standard quality and from central manufacturing plants by subsequent coating with a suitable paint at the final producers of the plant for special conditions of use, d. H. for high creep resistance and low flammability.

Explanation of the essence of the invention

According to the invention, the object is achieved by coating (brushing, spraying, dipping) the insulating part with a cold-curing, easily processable insulating material with corresponding properties in the form of a lacquer or a paste, in particular high creepage and fire resistance.

As a suitable insulating z. B. a silicone rubber two-component paste type NG 3000 (with = 8 Io crosslinker 112) of the VEB Chemiewerk Künchritz, with at least $ 5 a flame-retardant mixture of tris-3-chloro-2-hydroxypropyl - phosphate

_{0 =} ρ 0 -CH ₂ -CH-CH ₂ Cl

OH 3

and antimony trioxide (weight ratio 80:20) is modified, application. The crosslinker brings about good adhesion between the protective layer and the carrier material. Normal qualities

^ 5von printed circuit board materials based on epoxy or phenolic resin are by subsequent treatment with the coating material according to the invention both in their creep resistance (B = 300 to 400, initial value = 120 to 150) and in their fire behavior (increase from BG 3/4 to BG 2 / 3) improved. The economic advantage of covering special requirements for electrotechnical / electronic assemblies for special application conditions by modifying standard assemblies at the final producer is obvious.

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The ability to repair damaged areas by subsequent painting is another advantage of the method. B. according to the requirements of shipbuilding for the production of printed circuit boards, the page with the circuit traces in the 5Eegel for reasons of corrosion protection must be painted, occurs in the case of modification by coating no significant additional technological effort.

embodiments

Example 1: In a 150 ml beaker, 100 g of cold-setting silicone rubber paste type NG 3000 (VEB Chemiewerk Nünchritz) are thoroughly mixed with 5 g of tris-3-chloro-2-hydroxypropyl phosphate and 8 g of crosslinker 112 using a vigorous stirrer (1 to 2 minutes). Then, by brief evacuation (= 2 minutes) in a desiccator or in a vacuum oven, the mixture is freed of trapped air and immediately used for coating.

Example 2: 100 g of NG 3000, 10 g of tris-3-chloro-2-hydroxypropyl phosphate and 10 g of crosslinker 112 are mixed under the same conditions as in Example 1, degassed and used for coating. The levels of crosslinker are increased over the amount used for the corresponding unmodified silicone rubber paste because the flame retardant additive has a retarding effect on the cure.

i o qi. yes λ .ι η ._ ,. n. ,.

Claims (2)

invention claim 1. A method for simultaneously increasing the creepage and flame resistance of insulating parts electrical / electronic assemblies, in particular of base material of laminates for printed circuits, characterized in that by coating with a thin coating of a cold-curing insulating the parameters of standard qualities on the requirements of increased safety regulations corresponding values are brought. fO 2. Method according to claim 1, characterized in that products from standard production can be subsequently adapted to the increased requirements for certain applications at the final producers. 3 o Method according to claim 1 and 2, characterized in that Ijdaß for coating a modified silicone rubber two-component paste NG 3000 according to TGL 212Ü2 with a proportion of 5 to 10 % iris - 3 - chloro - 2 - hydroxypropyl - phosphate flame retardant additive and with 8 to 10 % crosslinker 112 is used. A. The method of claim 1 and 2, characterized in that it allows easy repair of superficial defect parts of insulating parts of electrical and electronic assemblies by coating. • i O O i. -Hm