EA037451B1 - Method for making printed circuit boards - Google Patents

Abstract

The invention relates to radio engineering, and provides a method for manufacturing printed circuit boards and a device for manufacturing a conductive circuit, and can be used for both small-scale and mass production of electrical and electronic products with complicated circuitry. When implementing the method, a blanking die punch is pre-made with a relief pattern of conductors on its surface. The punch has sharpened cutting edges at the points of contact with the conductive layer on the dielectric substrate, which are formed by cutouts of various sections, for example triangular, semicircular, or trapezoidal. A heat-activated adhesive film and a layer of conductive foil are applied on a solid dielectric substrate. The assembled set of layers is fixed in the press with installed punch. The punch is lowered with a minimum pressure sufficient for penetrating the sharp edges of the punch and cutting through the foil, while simultaneously pasting the conductive pattern to the dielectric substrate. As a result, the unglued foil cut off by the punch is easily removed by hand or an adhesive roller, and only the pattern of conducting circuit fixed with an adhesive material remains on the dielectric substrate. The technical result is the production of a relatively inexpensive high-quality conductive circuit on a substrate for use in printed circuit boards, which can be manufactured without the use or without the formation of chemicals hazardous to the environment.

Description

The invention relates to radio engineering, in particular to the manufacture of printed circuit board conductors.

The inventive method for manufacturing printed circuit boards is intended for both small-scale and mass production of printed circuit boards and is suitable for the manufacture of electrical and electronic products with a complex wiring diagram.

As a direct result of the development of the circuit board industry, the volume of environmentally hazardous chemicals from conventional etching and deposition processes is increasing in parallel. For example, typically 4000 liters per day of blackout remover and 3800 liters of developer solution per week are prepared for one PCB manufacturing plant. This toxic waste must be transported to dedicated hazardous waste disposal sites. Thus, there is a need for a non-chemical method for making conductive circuits.

There is a known method of manufacturing printed circuit boards, which consists in applying a metal foil to a substrate, forming a protective mask on the surface of this foil with etching of blank areas. USSR author's certificate No. 273867, IPC N05K 3/06, 17.09.1973

The disadvantages of this method are the large number of technological operations, low productivity and the harmful effects of the components of technological production on people and the environment.

Known mechanical method of manufacturing a printed circuit, including the formation of a sheet of conductive material to form protrusions and grooves, of which one forms a conductive circuit, and the other - waste material, which are then mechanically removed; Patent No. RU 2138930, IPC NO5K 3/00, NO5K 1/02, 09/27/1999. Thus, the conducting circuit is supported by a dielectric layer due to the self-centering of the conductors.

The disadvantages of this method are that ducted conductors cannot be used in flexible printed circuit boards. It also requires precision milling to remove unwanted metallic material in this method. Also the disadvantage of this method is the significant waste of metal.

Known mechanical method of manufacturing a printed circuit board, including the formation of a convex conductive pattern on a foil-clad dielectric substrate by perpendicular shift of the conductive material deep into the non-conductive substrate with simultaneous rupture of the foil using the pressure of the stamp; UK patent GB 1138628 (A), IPC NO5K 3/00, 01.01.1969 This technical solution was adopted as a prototype.

The disadvantages of this method are the formation of burrs along the entire length of the lines of material rupture, the difficulty of removing unused metallic material, the need to use a relatively thick substrate and a large number of technological operations.

The object of the invention is to provide a relatively inexpensive high quality conductive circuit on a substrate for use in printed circuit boards, which can be manufactured without or without the formation of environmentally hazardous chemicals.

The technical result is to simplify the technology of manufacturing printed circuit boards, expand technological capabilities, improve environmental safety.

The economic result is a reduction in application costs, selective removal of the required contact coating.

The technical result is achieved by the fact that in the method of manufacturing printed circuit boards, including the manufacture of a dielectric substrate, fixing a flat electrically conductive pattern and forming an image of the circuit on a dielectric material is carried out using a punch that repeats the pattern of the circuit, while cutting the conductive material along the edges of the tracks.

The conductors can be made in accordance with the invention in any configuration, and they can be arbitrarily placed on any non-conductive base material.

The essence of the method is illustrated by drawings.

FIG. 1 shows a punching punch with a relief pattern of conductors on its surface.

FIG. 2 shows a preform consisting of a substrate, a hot-melt film and a conductive foil.

FIG. Figures 3 and 4 show the initial phases of board manufacturing.

FIG. 5 shows a cross-section of the finished board.

FIG. 6 shows the conductive paths following different paths on the surface of the substrate.

The numbers indicate:

- punch;

- adhesive material;

- foil;

- dielectric substrate;

- punch protrusions.

- 1 037451

The method is implemented as follows.

Pre-cut punch 1 is made with a relief pattern of conductors on its surface (Fig. 1). Steel can be used as the punch material. The punch is formed by machining with a mechanical tool or by extruding a plastic material through a stencil, followed by curing (for example, ceramics). A hot-melt adhesive film 2 and a foil layer made of a conductive material 3 (Fig. 2) are placed on a solid dielectric substrate 4. In another embodiment, a stencil of a release material is laid on a solid dielectric substrate (to avoid adhesion of the foil between the conductors), then a hot-melt adhesive film and foil. The assembled set of layers is fixed in a press with an installed punch 1, made according to the claimed method (Fig. 3). The punch 1 has sharpened cutting edges at the points of contact with the conductive layer on the dielectric substrate, formed by cutouts of various sections, for example, triangular, semicircular or trapezoidal. The punch 1 is lowered by means not shown with a minimum pressure sufficient for the sharp edges of the punch to penetrate and cut through the foil while adhering the conductive pattern to the dielectric substrate (FIG. 4). As a result, the non-glued foil cut off by the punch is easily removed by hand or with an adhesive roller, and only the pattern of the conductive circuit 3, fixed by the adhesive material 2, remains on the dielectric substrate 4.

In another embodiment, the device contains a roller with protrusions repeating the pattern of the conductors and having sharpened cutting edges at the points of contact with the conductive layer on the dielectric substrate, formed by cutouts of various sections, for example, triangular, semicircular or trapezoidal.

This method provides significant advantages over known imaging and etching methods, or over the additive method (metallization) commonly used to make conductive circuit boards. This method also allows the use of metal sheets or foil with minor inclusions, which cannot be used in a method involving an etching operation, since this can lead to an uneven etching rate. Also, the method according to the invention achieves the same output of circuits in which the metal foil has different thicknesses. The known method is based on image formation and etching, in which the linear velocity is directly proportional to the mass of the foil, since more time is spent etching a thick foil than etching a thin foil.

The method according to the invention allows a variety of different conductive materials to be processed, for example brass, copper, aluminum, etc., without the risk of chemical contamination that is unavoidable during etching.

The drawings show that the conductive paths are straight and parallel to each other in a densely packed group, however, the conductive paths can follow different paths along the substrate or interconnect depending on the particular circuit application due to the corresponding punch pattern (FIG. 6).

The punching process not only forms a conductive pattern, but also hardens it.

Any protective coating can be applied to the conductor circuits or their terminal points in accordance with the present method, since the present method makes it possible to produce conductor circuits from sheet or roll conductive material, which has been previously applied with a suitable contact coating, for example, gold. Only a mechanical method can solve this problem, since conventional pickling solutions will not remove gold and, therefore, additional processing steps will be required. Thus, the present method significantly reduces the cost of applying and selectively removing the desired contact coating.

Thus, the technical advantages of the method according to the invention are the following: the method is effective both for mass production and for small-scale production;

any protective coating can be applied to the conductors;

the method eliminates the main problems of the production of printed circuit boards associated with foil etching, for example, deformation of the original photomask, dust or dirt, masking coating with scratches, inappropriate etching technology, etc .;

fewer technological operations;

the possibility of using aluminum foil;

the method can significantly reduce direct production costs.

Claims (3)

CLAIM 1. A method for manufacturing printed circuit boards, including making a dielectric substrate, forming a relief image of a circuit pattern in the form of recesses in it, applying a conductive layer on a relief surface of the substrate and removing the conductive layer from the protrusions of the substrate by machining, characterized in that a non-foil dielectric is used, an electrically conductive pattern and the formation of an image of the circuit on a dielectric material is carried out using a punch or roller, repeating the pattern of the circuit, with simultaneous cutting of the conductive material along the edges of the tracks. 2. The method according to claim 1, characterized in that during the formation of the conductive pattern of the circuit, there is no perpendicular shift of the foil material deep into the dielectric substrate. 3. The method according to claim 1, characterized in that a thin stencil of a release material is placed between the foil layer and the dielectric.