JPS6236900A - Manufacture of compound printed wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a composite board constructed by combining a flammable printed circuit board (hereinafter referred to as a flexible board) and a rigid printed circuit board (hereinafter referred to as a rigid board). Regarding lint boards, a flexible board and a hard board are joined together, and solder is applied to the flexible board with folds.
This invention provides a method for manufacturing a composite printed circuit board that allows electrically reliable wiring connections by melting all i→.

In particular, the present invention is intended to enable miniaturization of 1F child devices that require a three-dimensional printed wiring board.

[Conventional technology]

Recently, due to the demand for lighter, thinner, and shorter R1 slave devices, the printed wiring boards used for them have a high Mff.
multilayered, multilayered, and three-dimensional. In particular, attempts have been made to form an integrated circuit by fully bonding a flexible substrate and a rigid substrate, and bending the flexible substrate portion, in order to utilize a limited space three-dimensionally.

Many techniques have been proposed for the purpose of making a highly reliable connection between a twisted, flexible substrate and a solid substrate in a stacked manner.

For example, (1) JP-A-58-25866 discloses that a through hole is formed in the conductive portion of the wiring pattern of a flexible substrate, and a lead wire insertion hole having a diameter larger than that of the through hole is formed. Manufacture of a printed wiring board in which the conductive part of the wiring pattern of the flexible board is assembled into the inner wall of the hole of the hard board after the hard board and the metal board are assembled, and the inner wall pattern and the lead wire are fixed by complete soldering. A method is disclosed.

Next, (I) Japanese Unexamined Patent Publication No. 54-157271 discloses a hard-flexible composite printed wiring board characterized in that a souffle hole is formed integrally on a hard substrate and a flexible substrate. ing.

In addition, (Button JP-A No. 55-77094 discloses that through-holes 1V are installed on a hard board, and the connection terminals having gas vent holes are overlapped with all through-holes F of a flexible board, and solder is used to mount electronic components on the hard board. When it comes to attached T, Su~Ho/I
A method of connecting a flexible substrate and a rigid substrate by joining them by rising solder is disclosed.

(5) Japanese Unexamined Patent Publication No. 56-115598 discloses that the size of the conductor land portion and the hole portion forming the connection portion of the flexible board is made larger than that of the hard board, and the land diameter is set to a corresponding size, After overlapping these connection parts and fixing them, apply solder from the flexible board side and connect 1. A flexible substrate connection method is disclosed.

Furthermore, (v) JP-A-57-12129 '1' discloses a first substrate on which a conductive wiring pattern is formed on both sides, and a first substrate on which a conductive pattern is formed on at least one side. The second printed circuit board and the second printed circuit board are stacked so that the connection lands with through holes formed in the mutual wiring patterns face each other, and a gap is formed in the connection land. A method of manufacturing a composite printed circuit board is disclosed, which includes solder dipping from one printed circuit board surface.

In this way, in (1) to (V) printed wiring boards and their manufacturing methods, the connections between the flexible board and the hard RG board are made in a thorough manner, and at the same time, the flexibility of the flexible board is utilized. The purpose of this is to form a three-dimensional wiring circuit.

[Problems to be solved by the invention from 1 to 1] The joint portion between the flexible substrate and the rigid substrate bonded according to the above (1) requires a lot of time to narrow down the conductive parts of the flexible substrate (7. In addition, in (1) above, the flexible board and the hard board are integrated, and the through holes are formed, so the reliability of the connection is significantly improved, but after the two boards are integrated, drilling, plating, etc.
Processing such as patterning and etching is performed, and the process is complicated, making it difficult to apply to a substrate having wiring circuits on both sides, and making it impossible to obtain three-dimensional high-density wiring circuits.

In (1), connect the connecting terminals of the flexible board that has gas vent holes on the through-holes of the double-sided rigid board through-hole.
When overlapping and soldering, it is necessary to solder the hard substrate and the flexible substrate in a fixed state using all jigs, which is difficult for mass production.

(5) and (Ma) both connect the wiring between a flexible board and a rigid board by solder dipping.
Generally, since wiring connections are made by applying solder from the flexible substrate side, there are restrictions on the mounting position of chip components, etc. Furthermore, when soldering is completely applied from the hard substrate side, blowholes occur frequently in wiring connection holes with a diameter of 1M or less, making it impossible to make highly reliable wiring connections. In addition, when the diameter of the wiring connection hole is set to 1 11J or more, there are drawbacks such as low reliability -F due to falling of raised solder.

The present invention was made in order to solve these drawbacks, and it is a composite printed circuit board that can increase the overall reliability of the connection between a rigid board with 1 to 4 wires in high density and a +i (flexible board). All manufacturing methods are provided.

[Means for solving all the problems, their functions and embodiments] According to the present invention, in order to connect the 1F flexible board and the hard board by wiring, the flexible board and the hard board are arranged opposite to each other. Provide a connection hole in the &W connection part.

In this case, it is advantageous for the connection hole diameter of the combustible substrate to be larger than that of the hard substrate.

The wiring connection holes of the flexible substrate and the rigid substrate are aligned so that they face each other, a contact layer is provided so that a gap is provided around the wiring connection holes, and the bonding is cured. Like this 17
[At a glance] After the process of fully bonding the flexible board and the IT board, the solder is fully applied to the flexible board surface, and then heated and melted, allowing the molten solder to flow into the wiring connection hole of the hard board, making it extremely A reliable electrical connection can be obtained.

A conductor connection land is provided around the wiring connection hole, and the surface of the wiring conductor is made of a material such as copper, solder, gold, or tin. One or both sides of the flexible substrate and the rigid substrate are protected with a cover film or ink for solder resist.

As the base material of the flexible substrate that can be used in the present invention,
There are films made of polyimide resin, epoxy resin, bismaleimide triazine resin, polyester/l/resin, and composites of these and glass cloth. Alternatively, the adhesive layer can be formed by heating and curing a thermosetting resin.

On the other hand, as the hard substrate, a glass epoxy substrate is usually used, but it may also be a glass polyimide, glass epoxy composite, or paper phenol substrate.

- Another invention! (Thus, the resulting composite printed circuit board is often used to form a complete three-dimensional wiring circuit, so the hard board is connected to the flexible board by solder melting f/c (17), and then the flexible board is connected to the flexible board. The unnecessary part of the hard board corresponding to the bending part of the board should be treated with 77II in advance to make it possible to easily remove the PC by scraping, punching, perforating, etc., and the unnecessary part to be removed can be Not bonded to flexible substrate.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a cross-sectional view of a wiring connection hole in a state in which a burnable substrate and a hard substrate are bonded via an adhesive layer, and solder beams for wiring connection between the two are completely printed.

FIG. 2 is a cross-sectional view of the wiring connection hole in a state where the printed solder paste is heated and melted and dropped into the wiring connection hole.

A solder resist film (3) is provided so that the surface of the self-line connection hole (2) formed in the nJ burnable substrate fl) is exposed. Similarly, the wiring connection hole (
5) and a solder resist film (6). The burnable substrate and the hard substrate are bonded and hardened by an adhesive shaft (7).

In this adhesive layer, gaps are provided around opposing wiring connection holes in the flexible substrate and the rigid substrate, respectively. The solder paste (8) printed on the burnable substrate is heated and melted, and can be dropped into the wiring connection hole of the hard substrate. Similarly, the solder may be applied by a dispenser or the like in addition to the printed form.

After melting and solidifying the solder (9), it is preferable to determine the volume of the wiring connection hole of the combustible substrate, the hard-flexible substrate, and the hard substrate and the volume of the void provided in the adhesive layer as a guide.

Further, when surface-mounting or insert-mounting electronic components onto the composite printed circuit board wire-connected in this manner, the electronic components are immersed in a solder melting bath.

In this case, the wiring connection hole diameter of the hard board is 9.311111
The following are preferred. In wiring connection holes of 0°8IIj or larger, the solder connected to the wiring falls 17 when immersed in the solder melting tank after the wiring is connected due to the heating and melting of the sakaki, causing electrical damage to the wiring connection part. Reliability decreases.

Furthermore, in order to increase the reliability of wiring connections, the contact N m
t7) is preferably provided so that the land portion of the wiring connection hole is not covered.

When arranging circuit wiring and components, component leads are inserted into the wiring connection holes provided in the combustible board and the hard board, and then immersed in a solder melting tank. It is also possible to connect by combining wiring connection by heating and melting, which is true≠kon.

FIG. 8 is a sectional view of a state in which a plurality of hard substrates and flexible substrates are connected by wiring. The bent portion or unnecessary portion Q[) for forming a three-dimensional wiring circuit can be easily removed after wiring connection and component mounting according to the present invention. There is a perforation or slot between the
After processing, the integrated state is bonded and hardened to the burnable substrate via an adhesive layer. At the same time, no adhesive layer is provided on the bent portions and unnecessary portions so that they can be easily removed.

It has the feature that it can be used as a substrate with a multilayer structure through the holes.

When mounting components, immersion into the solder melting tank can be done from either the iT annealing board side or the hard board side, but chip parts are usually mounted on the hard board side in order to obtain flatness of the external shape of the three-dimensional wiring circuit. However, it is often immersed in a solder melting tank.

Further, as the flexible substrate used in the present invention, a film usually made of polyimide resin, epoxy resin, bismaleimide triazine resin, or polyester resin is used. However, in wiring connections for high-density wiring circuits, when bonding a flexible substrate and a rigid substrate via an adhesive layer, it is necessary to increase the precision of the positions of the wiring connection holes that face each other. It is preferable to use a combustible substrate composited with.

The thickness of this composite flexible substrate can be 0.8 mm or less.

〔Effect of the invention〕

As explained above, according to the present invention, the method for connecting a composite printed wiring between a flexible board and a rigid board essentially solves problems that occur in wiring connections using conventional methods such as solder blowholes and solder drops. It can be solved. According to the present invention, since high reliability of wiring connections can be obtained, not only terminal connections but also high-density wiring circuit formation with a multilayer wiring structure of combustible substrates and hard substrates can be formed using three-dimensional circuit formation. There is an advantage that they can be done at the same time.

As described above, the present invention is extremely useful for making electronic equipment lighter, thinner, shorter, and three-dimensional.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a wiring connection hole after the solder paste printing process according to the present invention, FIG. The figure is a sectional view showing an example of a composite printed circuit board obtained by the present invention. l...Flexible board 2...Wiring connection hole 8...Solder resist 4...Hard board 5...Wiring connection hole 6・・・・・・
Solder resist 7...Adhesive layer 8...
... Solder paste 9 ... Heat-melted solder 10 ... Part 11 to be removed for bending
······slit

Claims (1)

[Claims] 1. A method for manufacturing a composite printed circuit board in which a flexible substrate having a printed wiring circuit on one side or both sides and a rigid substrate having printed wiring circuits on both sides or multiple layers are connected by wiring. A step in which wiring connection holes are provided between the flexible substrate and the rigid substrate so as to face each other, and the wiring connection portion between the flexible substrate and the rigid substrate is laminated via an adhesive layer so as to have a space around the wiring connection hole. 1. A method for manufacturing a composite printed circuit board, comprising at least the step of connecting a part or all of the flexible substrate to the surface of the flexible substrate by heating and melting solder. 2. The method for manufacturing a composite printed circuit board according to claim 1, characterized in that no adhesive layer is present in unnecessary parts and removed parts of the hard board. 3. The method for manufacturing a composite printed circuit board according to claim 1, wherein the wiring connection hole diameter of the hard substrate is 0.8 mm or less. 4. The method for manufacturing a composite printed circuit board according to claim 1, wherein the flexible substrate and the rigid substrate are connected so as to form a multilayer wiring structure. 5. The flexible substrate is characterized by using a film made of polyimide resin, epoxy resin, bismaleimide triazine resin, or polyester resin, or a composite material of these resins and glass cloth as the flexible substrate base material. A method for manufacturing a composite printed circuit board according to claim 1.