RU2580512C1 - Method of producing flexible-rigid printed circuit board - Google Patents

Abstract

FIELD: electronic equipment.

SUBSTANCE: invention relates to production of flexible-rigid printed circuit boards (FRPC). Technical result is achieved by a method for manufacturing flexible-rigid circuit board, comprising forming by photolithography and subsequent galvanic deposition of conductive components of circuitry on combined flexibly rigid support FRPC plating finish and protective coatings before applying final coating on rigid part and slots in contact windows, flexible part FRPC applied protective dry solder mask, which is light-cured via UV-irradiation, is subjected to polymerisation for a predetermined circuit protective mask, followed by a final step of metallisation FRPC then removed windows above flexible part together with mask before full surface disclosure flexible part FRPC.

EFFECT: method of producing flexible-rigid printed circuit board, a protection of flexible part (foiled polyimide with copper conductors and cover film) from effect of aggressive chemicals at stage of formation of finishing electroconductive coating (hot melting POS or immersion coating).

1 cl, 3 dwg, 1 ex

Description

The invention relates to the field of electrical engineering and radio engineering, in particular to the manufacturing technology of flexible-rigid printed circuit boards (GZHPP).

The problem solved by the invention lies in the need to protect the vulnerable flexible part of the GLCP at the stage of forming the final conductive coating (hot fusion of the PIC or applying immersion coatings) from the effects of aggressive chemicals, temperature and mechanical influences.

A method for manufacturing flexible printed circuits is known from the prior art (RF patent No. 1632352, IPC H05K 3/28, publ. 11/20/1995), according to which, to improve the quality of printed circuits, it is possible to reduce the temperature gradient and prevent uncontrolled deformation in the foil dielectric film by controlled plastic deformation to align the workpiece at the preliminary stage of stamping the workpiece from a foil dielectric film, to ensure uniform thickness of the photoresist layer and mproving etching conditions.

As a prototype of the claimed method is known for the manufacture of GGPP, in which a protective adhesive tape is used, which is placed on the slots in the hard part of the GGPP, formed before pressing the workpiece (Technologies in the production of electronics, part III. Flexible printed circuit boards. / Ed. AM Medvedev and G.V. Mylova. - M.: Publishing House "IDT Group", 2008, p. 130-131).

The disadvantages of the analogues are that they do not provide sufficiently reliable protection of the flexible part of the GLCP from the effects of aggressive chemicals at the stage of forming the final conductive coating, which can leak into the slots in the hard part of the GLCP and significantly reduce the quality of the finished products.

The objective of the invention is to develop a method of manufacturing a flexible-rigid printed circuit board, which provides for the protection of the flexible part (foil polyimide with copper conductors and a coating film) from exposure to aggressive chemicals at the stage of forming the final conductive coating (hot fusion of PIC or immersion coatings).

A new technical result provided by using the proposed method for manufacturing a flexible-rigid printed circuit board is to provide reliable protection of the flexible part (polyimide with copper conductors and coating film) that is at risk of destruction from the effects of aggressive chemicals at the stage of forming the final conductive coating (hot fusion of PIC or immersion coatings).

These tasks and a new technical result are ensured by the fact that, in contrast to the known method of manufacturing a flexible-rigid printed circuit board, which includes forming by photolithography and subsequent galvanic deposition of conductive components of an electrical circuit on a combined flexible-rigid base GZHPP, applying the finish and protective coatings, according to the proposed the method before applying the finish coating on the hard part and on the slots in the contact windows of the flexible part of the GLCP, a protective dry solder is applied The mask, which is illuminated by UV irradiation, is polymerized to obtain the specified contour of the protective mask, after which the final stage of metallization of the GSP is carried out, then the windows over the flexible part are removed together with the mask until the surface of the flexible part of the GSP is fully opened.

The proposed method of manufacturing a flexible-rigid printed circuit board is illustrated as follows.

In FIG. 1 shows a view of the assembly of a flexible-rigid printed circuit board after applying the finish coating (the slots are closed with a solder mask), where 1 is a layer of polyimide (the flexible part of PP), 2 is a coating film, 3 is foil fiberglass + galvanic copper, copper foil + galvanic copper ( hard part of PP), 4 - topcoat, 5 - prepreg, 6 - slots 7 - windows, 8 - protective solder mask.

Initially, prefabricated flexible and rigid parts of the GZHPP are made, then they are formed by photolithography and subsequent galvanic deposition of the conductive components of the electrical circuit on a combined flexible-rigid GZHPP base.

Before applying the final and protective coatings of the GZHPP, a protective dry solder mask is applied to the hard part and to the slots in the contact windows of the flexible part of the GZHPP. The mask is applied to the entire workpiece (including the slots in the windows above the flexible part).

Products thus obtained with coated protective coatings are exposed to UV radiation and the polymerization process is carried out to obtain a predetermined protective mask contour, after which the final stage of metallization of the liquid metal-plastic coating is carried out.

Then remove the windows above the flexible part together with the mask until the surface of the flexible part of the GLCP is fully exposed.

After applying the topcoat, the windows over the flexible part together with the applied mask are removed, releasing the flexible part of the GLP.

In FIG. 2 depicts the GLCP in finished form after removing the window 7 above its flexible part with the previously applied mask 8.

It has been experimentally established that the operation of protecting the flexible part of the GZHPP using the specified dry solder mask improves the quality of finished products, since this coating is reliable protection of the GZHPP before the subsequent operation of metallization of the GZHPP.

Thus, the use of the proposed method provides a higher than achieved in the prototype, the technical result, which consists in providing reliable protection of the endangered flexible part (polyimide with copper conductors and coating film) from exposure to aggressive chemicals at the stage of formation of the final conductive coating (hot fusion Pic or immersion coatings).

The possibility of industrial implementation of the proposed method is confirmed by the following example.

Example 1. In laboratory conditions, the proposed method was tested to obtain a prototype GZHPP, depicted in FIG. 3, where 1 is the flexible part (polyimide with copper conductors and the coating film) GZHPP, 2 is the metallized hole, 3 is the rigid part of the board (fiberglass with conductive pattern, metallized holes, a protective solder mask and a finish coating). The manufacturing technology of GZHPP consisted of the following operations:

- cutting flexible (polyimide with copper conductors and coating film) and hard (fiberglass with a conductive pattern, metallized holes, a protective solder mask and a finish layer) of blanks to the size of group blanks (package of homogeneous elements);

- the formation of base holes in the workpieces;

- formation of conductors on flexible layers of a pattern (by a sequential combination of photochemistry and etching methods);

- fixing the coating film on a flexible layer of polyimide by pressing;

- the formation of milling grooves (partial or complete grooving of the grooves) in the hard laminated layers of the GZHPP for the subsequent release of the flexible part at the final stage of the manufacture of finished GZHPP;

- cutting of connecting gaskets (prepregs) with the removal of certain sections to protect the flexible areas from gluing together and with hard parts;

- assembly of the package of rigid and flexible layers by pressing;

- pressing the assembled package;

- the formation of holes for metallization by drilling;

- chemical and electrochemical metallization of holes:

- the formation of a negative image on the outer hard layers of the workpiece GZHPP;

- etching of the copper layer and the removal of photoresist;

- control of electric parameters of GZHPP;

- the application of a protective mask on the hard base of the GZHPP;

- applying a solder mask;

- exposure of the solder mask;

- the manifestation of the solder mask.

A dry protective mask is applied to the entire hard part (including the cuts in the windows above the flexible part of the GSP), the working photo mask is modified so that zone A on it is transparent for UV irradiation during exposure operations. The illuminated areas are photopolymerized and lose their ability to dissolve at the stage of development. Over the slots in a rigid base, reliable protection is formed from the reagents used during the operation of applying the finish coating (Fig. 2): 1 - coating film; 2 - a layer of polyimide with a copper coating; 3 - a layer of foil + galvanic copper; 4 - topcoat; 5 - prepreg; 8 - mask. The subsequent operations of manufacturing the finished GZHPP were as follows:

- application of the finish coating;

- conducting control of electrical parameters;

- carrying out processing along the contour.

When the circuit board is cut off, the rigid part of the GSPP, covering the flexible window with the protective mask applied, is released (falls out), resulting in the formation of the finished GSPP. In FIG. 3 depicts the GLP after application of the topcoat. The slots are closed with a solder mask.

The resulting sample of GLPP was tested.

Claims (1)

A method of manufacturing a flexible-rigid printed circuit board (GZHPP), including the formation by photolithography and subsequent galvanic deposition of conductive components of the electrical circuit on a combined flexible-rigid base of GZHPP, the application of top and protective coatings, characterized in that, in order to provide protection against chemicals and temperature effects at the stage of the operation of hot melting the surface of the flexible component of the GZHPP, before applying the finish coating to the hard part and to the slots in the cont In the windows of the flexible part of the GLCP, a protective dry solder mask is applied, which is illuminated by UV irradiation, polymerized to obtain the specified contour of the protective mask, after which the final stage of metallization of the GLCP is carried out, then the windows over the flexible part together with the mask are removed until the surface of the flexible part is fully exposed GZHPP.

Images