RU2496286C1 - Manufacturing method of flexible relief printed-circuit boards for electronic and electrotechnical equipment - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: relief is applied onto thermoplastic material on two opposite sides, one of which is mirror reflection of the shaped profile. Separate parts of die mould in combination with free masks are used as provision of required stiffness when performing operations of cleaning, activation of surface of base and application of conductors. This invention allows creating electronic and electrotechnical products with high operating properties.

EFFECT: creation of manufacturing method of relief printed-circuit board on maximum thin and flexible insulation base, which has considerably smaller weight and dimensions in comparison to conventional relief printed-circuit boards.

5 cl, 5 dwg

Description

FIELD OF THE INVENTION

The invention relates to the field of manufacturing switching means and certain types of products for electronic, communication and electrical equipment, and more particularly, to methods for manufacturing flexible embossed printed circuit boards.

State of the art

Known three-dimensional flexible electronic module according to Russian patent No. 2119276 from 09/20/98, H05K 3/36, consisting of unpacked electronic components, housing electronic components and microplates with unpacked active and passive electronic components. Unpackaged electronic components, enclosed electronic components and microboards, in addition to internal connections, are electrically connected to each other by flexible corrugated switching boards with a variable cross-section. In this case, preliminary forming of patch boards according to the external profile of the module is provided.

This design, possessing all the advantages of three-dimensional modules (first of all, high layout density), is able to change its external shape: compress and expand, bend in any direction without changing its functional properties. But in the said patent, flexible printed circuit boards have only a flat shape, and a method for manufacturing such printed circuit boards is not given.

A known design of an electronic module having a flexible printed circuit board with heat sink means according to US Pat. No. 3,766,439, IPC H05K 7/20, dated October 16, 73. A component of an electronic circuit is described which is advantageous especially for a multilayer circuit board design made primarily from a flexible dielectric sheet as the base of the board, on which a copper coating is applied, covering the dielectric sheet before etching the conductors. The conductors are separated in accordance with the X and Y axes, with the conductors on each side of the dielectric being parallel to only one axis. The combination of commutation along the X and Y axes is realized by means of metallized holes, to which circuit elements can be connected. Plenary integrated circuits are connected to the board with their tops oriented towards the board, and the heat sink base in the opposite direction. By placing all planar housings on one side of the flexible board and folding the board into a loop, it is possible to achieve a high density of circuit components with heat-generating parts of planar housings directed to the outer sides of the structure hinges, ensuring that the planar housings are in thermal contact with the housing.

The advantage of this design is an attempt to realize an efficient heat dissipation from heating components to the housing. But this design uses only flat boards, it is stationary and does not allow any arbitrary bending.

Known assembly of a printed circuit board according to US patent 3,819,989, IPC H05K 1/04, dated June 25, 74. Patented is the assembly of a printed circuit board connecting a plurality of circuits made of a single blank, a flexible tape carrying a plurality of conductors leading to circuits located on the circuit circuit boards. The boards are located at right angles to the main tape at the end of loops carrying conductors branching to the circuit board. The tape loops are folded so that the boards remain in mutually parallel planes perpendicular to the main tape.

This design is quite technologically advanced, since it involves the manufacture of all substrates and a commuting base from a single workpiece. But this design cannot be considered complete, since elements of mechanical rigidity, heat sink and other structural elements are not provided. The manufacturing technology of the backplane is not shown.

John Fluke Manufacturing Co., according to US patent 4,604,799, H05K 3/02, dated 03.09.82. "Method for the manufacture of molded printed circuit boards" has developed a process for metallizing a plastic molded substrate with through holes, around which there are circular recesses, and between the holes there are grooves for conductors. After cleaning, the substrate is subjected to heat treatment to relieve mechanical stress and give it flatness. Then a layer of copper is sprayed onto the entire surface and through holes. Removing the copper coating from whitespace is done by machining, such as grinding. As a result, the copper coating remains only in the grooves, recesses and through holes. If it is necessary to protect the surface of the dielectric from impurities, the entire surface is covered with a solder mask by screen printing. As a substrate, polysulfone, polyetherimide, epoxide and other materials are used.

This method implements one of the methods for manufacturing embossed printed circuit boards only on a rigid base with a significant thickness. However, this technical solution is the closest analogue (prototype) of the present invention.

The main objective of this invention is to provide a method for manufacturing a embossed printed circuit board on an extremely thin and flexible insulating base, which has a significantly lower mass and size compared to traditional embossed printed circuit boards.

Disclosure of invention

To achieve this goal in a method of manufacturing flexible embossed printed circuit boards for electronic and electrical equipment, including forming a relief and making holes in the polymer base, cleaning and activating the surfaces of the polymer base, applying conductors and building up their thickness mainly by hot tinning, the polymer base is made from optically transparent thin and flexible thermoplastic material, form a relief on two opposite sides of thermoplastic material, one of which is a mirror image of the formed profile, after which cleaning, activation of the surfaces of the polymer base, application of conductors and metallization of the holes are carried out locally, in a single vacuum cycle, through a “free” mask installed tightly to the relief, and the application of conductors and metallization the holes are produced primarily by vacuum deposition of metal films, and the thickness of the conductors is increased until the flexibility of the embossed printed circuit board is maintained.

Moreover, the deposition of conductors on the base can be carried out through "free" masks having bent zones that perform camouflage and reflective functions.

For a tighter installation of the mask to the relief when forming the relief, parts of the mold are used alternately as a retaining element of the polymer base when cleaning, activating and applying conductors, and part of the mold is made of magnetized material, and the polymer base is placed between the “free” mask and magnetized part of the mold,

or part of the mold is made of non-magnetic material, a polymer base is placed between the "free" mask and the non-magnetic part of the mold, and a magnetic plate is placed on the back of the part of the mold.

The thickness of the conductors is increased until the relief is completely filled with conductive material.

Brief Description of the Drawings

The invention is illustrated by drawings, where

figure 1 shows the operation of forming a film of a polymer base;

figure 2 shows the operation of the vacuum deposition of conductors through the "free" mask;

figure 3 shows a fragment of a flexible embossed printed circuit board after two-sided deposition of conductors;

figure 4 shows a fragment of a flexible embossed printed circuit board after installing an electronic component on it;

figure 5 shows a fragment of a flexible embossed printed circuit board with filling the relief with conductive material.

The implementation of the invention

To create a relief in the polymer base 1 (Fig. 1), two parts of the mold 2 and 3 are used, having relief projections and depressions in the form of a mirror image. In this case, it is possible to manufacture both parts of the mold by the physicochemical method using the same photomask and photolithography. In a film polymer base 1 made of optically transparent thermoplastic material (for example, polyimide, or fluoroplastic, or heat-resistant polyethylene, etc.), through holes 4 are pre-stitched for subsequent electrical connection of conductors located on opposite sides of the polymer base 1. Through holes 4 can also be obtained after the operation of molding the polymer base 1. To form the relief, the upper 2 and lower 3 parts of the mold are preheated before softening temperatures of the polymer base material 1.

In order to avoid warping of the polymer base 1 during further operations of cleaning, activating and applying conductors (FIG. 2), the polymer base 1 after applying the relief is left in the lower 3 or upper 2 parts of the mold and a “free” mask 5 is applied to the polymer base 1, combining it with a relief pattern, for example, using the mounting pins and holes. The “free” mask 5 may have zones 6 bent towards the relief recesses to protect against the application of conductors on the gaps of the polymer base 1 and carry reflective functions when applying the conductors. Parts 2 and 3 of the mold can be made of magnetized material, which will ensure a snug fit of the “free” mask 5 and will prevent warping of the polymer base 1 during subsequent operations. Or the mold can be made of non-magnetic material. Then it is advisable to use the magnetic plate 7, providing a minimum distance between it and the "free" mask 5. The cleaning, activation and application of conductors 8, it is advisable to carry out in a single cycle. In this case, the method of vacuum deposition of metal films is mainly used. At the same time, the holes 4 in the polymer base 1 are metallized. The cleaning and activation operations are carried out mainly by the plasma-chemical method, and the “free” mask 5 is also cleaned.

After applying the conductors to one side of the polymer base 1, it is turned over and inserted into the relief of the mating part 2 of the mold. Next, the operations are repeated on another surface of the polymer base 1. After that, the board takes the form shown in Fig.3. A metallized hole 4 electrically connects the conductors 8 located on both sides of the polymer base 1. If necessary, electronic components 9 are placed in the recesses of the polymer base 1 (Fig. 4) and they are electrically connected to the conductors 8 with a conductive material 10. The entire relief the board somewhat loses its flexibility due to the stiffness of the electronic components 9, but retains all the advantages of embossed boards. Because the polymer base 1 is made of optically transparent material, the visual quality control of the soldering of the electronic component 9 to the conductor 8 is greatly simplified.

This method can be used to obtain high-current relief structures (figure 5). In this case, the polymer base 1 has a mutually entering relief with a dense arrangement of conductors 8 over the volume of the structure and a small pitch of the conductors 8 on both sides of the polymer base 1. After filling the relief with conductive material 10, a structure is obtained that consists almost entirely of conductive material with very thin insulation (almost equal to units or tens of micrometers). This can be successfully applied in the manufacture of electronic and electrical products, where it is important to obtain a great value of ampere turns.

This method of manufacturing a flexible embossed printed circuit boards can be used:

- for the production of flexible printed cables with a high density of conductors and high current loads for connecting nodes and devices of electronic equipment;

- for the manufacture of high-frequency embossed boards by shielding the conductors with a conductive layer deposited on the back side of the board, while the conductor is protected by a shield on three sides;

- in the manufacture of printed inductance coils, transformers, flat electric motors and other high-current products with high ampere-turns, as well as for the manufacture of inductors with predefined field shapes and quality factors;

- for the manufacture of electronic souvenirs and special equipment requiring mechanical flexibility while maintaining all the properties of embossed printed circuit boards;

- for the manufacture of heaters of arbitrary shape, including medical heaters of certain areas of the human body.

Claims (5)

1. A method of manufacturing a flexible embossed printed circuit boards for electronic and electrical equipment, including forming a relief and making holes in the polymer base, cleaning and activating the surfaces of the polymer base, applying conductors and increasing their thickness mainly by hot tinning, characterized in that the polymer base is made of optically transparent thin and flexible thermoplastic material, form a relief on two opposite sides of the thermoplastic material, one of which is a mirror image of the formed profile, after which cleaning, activation of the surfaces of the polymer base, deposition of conductors and metallization of the holes are carried out locally, in a single vacuum cycle, through a “free” mask installed tightly to the relief, and the deposition of conductors and metallization of the holes is predominantly by vacuum deposition of metal films, and the extension of the conductors is carried out until the flexibility of the embossed printed circuit board is maintained. 2. A method of manufacturing printed circuit boards according to claim 1, characterized in that the deposition of conductors on the base is carried out through "free" masks having bent zones that perform masking and reflection functions. 3. The method of manufacturing printed circuit boards according to claim 1, characterized in that the relief is formed using a mold, parts of which are used alternately as a retaining element of the polymer base when cleaning, activating and applying conductors, while part of the mold is made of magnetized material, and the polymer base is placed between the "free" mask and the magnetized part of the mold. 4. The method of manufacturing printed circuit boards according to claim 1, characterized in that part of the mold is used as a retaining element of the polymer base when cleaning, activating and applying conductors, while part of the mold is made of non-magnetic material, the polymer base is placed between " free ”mask and non-magnetic part of the mold, and on the back side of the mold part place a magnetic plate. 5. A method of manufacturing printed circuit boards according to claim 1, characterized in that the thickness of the conductors is increased until the relief is completely filled with conductive material.

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