DD221868A1 - METHOD FOR PRODUCING HIGH-LOW LADDER RAILS, SWITCH CONTACTS AND CONTACT ADHESIVES - Google Patents

Abstract

The invention can be used in the electrical and electronic industry for the production of high-resistance conductor tracks, for contacting integrated circuits and for producing switch contacts. The aim and object of the invention are to produce metal-free high-resistance tracks, switching contacts and contact adhesive in a simple and inexpensive way. This is achieved by using masses whose conductive component consists of soot particles or graphite particles. The electrical conductivity of the mass is determined by the proportion of leitfaehigen component. The graphite and / or Russteilchen be mechanically incorporated in a liquid present in plastic or paint by the particles (particle size about 50 mm) are added directly to a known plastic or paint composition and dispersed. For the production of highly concentrated on graphite and / or Russteilchen plastics or paints is prepared by mechanical dispersion first ago a graphite and / or Russsuspension ago, which is compatible with the plastic or paint solvent and Grenzflaechenaktive substances (medium and / or lankettige Fatty acids). This suspension is then admixed with a liquid plastic or lacquer known per se, optionally removing part of the solvents.

Description

Berlin, October 6, 1983 251/5495/111

Inventor / 'Dr, Norbert Baske

Elgar Linde

Helmut Winkler

Title ·, · -. · ^

Process for producing highly economical printed conductors, switch contacts and contact adhesive

Field of application of the invention

The invention, in the electrical and electronic industry for producing high-impedance traces for contacting of integrated circuits and for production of switch contacts using find · Furthermore, it is suitable for use in semiconductor manufacturing, such ₉ B "Wi assembly of electronic watches , Calculators or keypads for the control of electronically controlled equipment ·

C haracteristics of the Known technical solutions It is known to use hate with metallic conductive components, such as silver particles (US Patent 4,289,534), gold particles (üS patent »4 230 493) for the production of electrically conductive compounds on printed circuit boards. The metals are either in resins (DE-OS-2 614 840), adhesives

^{''::: ':} -..-''.'.'*

It is also known to use carbon black-containing polymer compositions for the production of heating cables (German Offenlegungsschrift No. 3,011,754) with a carbon black content of from 14 to 70% (DE-OS-2 536 361) or plastics (DE-OS 2 166 805) % By weight (DE-OS-2 018 825) and for the production of jacketed power transmission cables (DD-158 070) with an electrical resistance of 20 + 7kii / a.

Object of the invention

The aim of the invention is a simple and inexpensive production of metal-free high-resistance conductor tracks, switching contacts and contact adhesive.

·. , ^: ''

Object of the invention

The object of the invention is to replace the cost-intensive metallic components with cheap domestic raw materials.

Features of the invention

According to the invention, this is achieved by using hate whose conductive component consists of carbon black or graphite particles. The electrical conductivity of the mass is determined by the proportion of the conductive component. In general, the specific conductivity is specified by measuring the ohmic resistance and taking into account the corresponding area and length units. Thus, a conductor has approximately 60% by weight. Graphite has a specific conductivity of about 2 χ id * Ä m ² / i. The graphite and / or carbon black particles are incorporated mechanically in a liquid-containing plastic or lacquer by mixing and dispersing the particles (particle size about 50 μm) directly in a plastic or lacquer composition known per se. To produce graphite and / or carbon black particles highly concentrated plastics or paints is prepared by mechanical dispersion first a graphite and / or carbon black suspension ago, which is compatible with the plastic or paint solvent and surfactants (medium and / or langkettlge This suspension is then a per se known liquid plastic or paint

admixed, optionally removing a portion of the solvents.

The type dee to be used liquid plastic or paint depends on the Einsatagebiet. For example, dissolved in solvent nitro paints as well as two-component epoxy resin hardening systems can be used · For use both dip, spray and coating paints can reach. These coatings give as contacts or as interconnects a firm connection with the printed circuit board material, are scratch-resistant, temperature-resistant, resistant to tensile and compressive stress and sufficiently resistant to abrasion. Repairs that require a solution of the electrically conductive compound can be easily performed by using a suitable solvent without causing thermal or mechanical stress. A re-fastening takes place by wetting the contact points, subsequent application and hardening. The advantages according to the invention lie above all in the possibility of using different plastic materials which are rendered conductive by a correspondingly high proportion of graphite:

- The use of graphite instead of gold and silver leads to a significant cost reduction ·

- In printed circuit board manufacturing eliminates several previously necessary steps (galvanic coating, masking with photoresist, applying the structures and subsequent etching).

- When contacting components or possibly necessary detachment of these components: (repairs) eliminates the previously required by the use of solder heat load.

- As with previous gold contacts, the corrosion resistance is guaranteed. Practice has proved, however, that in the gilding process of printed circuit boards the already existing and not intended for gilding "*"; Conductor tracks are affected in their surface so that a Lötverbindang is difficult

- The flexibility of these tracks or contacts is better than with purely metallic versions ·

The soldering and desoldering of several closely adjacent terminals of components is greatly simplified by the inventive solution.

.Aua'fuhrungabe! Game

Example 1;

20 g of graphite powder are dispersed in 30 g of lacquer based on nitrocellulose by means of an ultrasonic bath for 20 min. During the dispersing, 50 ml of acetone are added in order to obtain the dispersion of low viscosity. This spreadable, high-resistance suspension can be applied in a customary manner.

Example 2:

25 g of graphite powder are dispersed with the addition of 1 ml of stearic acid in 200 ml of butyl acetate by means of a hand mixer. 30 g of nitrocellulose-based lacquer are mixed into the suspension with rapid stirring and stirring is continued for a further 10 minutes. This lacquer is tipped onto a printed circuit board template Conductors with a specific conductivity of 2 χ 10u2mm / m · This conductivity is completely sufficient for the high-resistance circuits known to us as well as for the control of liquid crystal displays.

Example 3:

1g of graphite powder is dispersed in the low viscosity component of a two component adhesive. Subsequently, the second component is mixed, so that a mass with 40 wt.% Graphite is formed. This viscous mass is sprayed relatively quickly onto a track or troweled over a template. This results in a high-resistance and particularly resistant conductor track with a specific resistance of about Ax 10 \ fLmm / m ·

Claims (1)

Erfindu ngsansprucfa J A method for producing hot-wire printed conductors and / or high-resistance, corrosion-resistant switching contacts and contact if ' Adhesive, characterized in that soot and / or graphite-containing © paint dispersions with 10 to 90% by weight of Ru ¹ JB and / or graphite gel by Tauch ™, Sprits or soldering methods are applied to 'circuit boards »wob @ i the specific Resistance of the printed circuit board® firmly connected, ρ f> ρ hardened paint dispersion 10 to 10 Jlmm / in, preferably 10 ** to 10 ^ 12. rar / m, is * 2 o Method according to item 1, characterized in that the cured lacquer dispersion has thermoplastic properties and / or is detachable from the circuit board by suitable solvents. 3. The method according to item 1, characterized in that the preparation of the carbon black and / or graphite-containing paint dispersions by mixing the soot »and / or graphite particles in a, compatible with the paint solvent with the addition of surface-active substances such as - To long-chain fatty acids occurs, followed by mechanical dispersion in known paint formulations. 4 · Method according to item 1 to 3, characterized in that as coating formulations z. B. overcrolacke or epoxy resin-2 component adhesives are used.