JPS59181596A - Method of producing flexible multilayer printed circuit 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] [Technical Field of the Invention] The present invention relates to a method for manufacturing a flexible multilayer printed wiring board, and in particular, in multilayering a single-layer flexible printed wiring board, the conductor portions of each layer are electrically connected to each other. It's about how to do it.

[Technical background of the invention]

Conventionally, when creating multiple layers of flexible printed wiring boards, through-hole plating connection method,
There are connection methods such as applying silver paste.

In the through-hole plating connection method, as shown in Figure 1, a hole is drilled in an insulating resin 2 on which a copper foil 1 is placed, and copper plating 3 is applied to the hole to form a through hole and establish continuity between the copper foils. It's a method.

Additionally, the connection method by applying silver paste is as shown in Figure 2, where a hole is made in the insulator (or foil 5) with copper foil 4 on both sides, and silver paste 6 is applied thereto to connect the through hole. This method creates a hole and establishes conduction.

[Problems with background technology]

However, although the through-hole plating method described above has excellent through-hole connection reliability, it requires many processing steps and has problems in terms of cost and mass production. Furthermore, although the connection method by applying silver paste is excellent as a simple through-hole connection method, it is usually limited to double-sided through-hole connection.

[Purpose of the invention]

In view of the above-mentioned points, the present invention is low cost and has excellent mass productivity.
Another object of the present invention is to provide a method for manufacturing a flexible multilayer printed wiring board that allows conductive connection between thick layers even when the multilayer flexible printed wiring board has three or more layers.

[Summary of the invention]

In the present invention, a single-layer flexible printed wiring board is created in which the conductor parts at the conductor connection points are exposed, and then a conductive adhesive is applied to the conductor connection points and an insulating adhesive is applied to the other parts. By laminating multiple single-layer flexible printed wiring boards and applying HD pressure heating, connections between each thick layer are achieved.
The company manufactures flexible multilayer printed wiring boards.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 is a sectional view showing a method for manufacturing a flexible multilayer printed wiring board according to the present invention. This figure shows a four-layer multilayer flexible substrate.

In FIG. 3, reference numeral F1. Fx, Fs, F
4 is an insulating film (insulating resin) such as a polyimide film or a polyester film, and a copper foil (for example, a thickness of 3
These single-layer flexible printed wiring boards 1tN1 to F4 are manufactured by a commonly used manufacturing method. However, conductor connection points a between each layer (Fl and F2, F? and Fa, F3 and F4 connection w1 place)
, b (connection point of 11 and F2), c (F2 and F3)
For connection points (b), do not apply an insulating film such as polyimide film or polyester film, and use copper foil 8.
Leave it exposed. Furthermore, regarding the conductor connection point a, the surface opposite to the connection surface of the board F1 and the surface opposite to the connection surface of the board F4, the surface opposite to the connection surface of the board F1 regarding the conductor connection point A, and the conductor connection point C. The copper foil on the opposite side of the connection surface of the board F3 is also exposed. In this way, conductor connection points a, b.

Single-layer flexible printed wiring board F with exposed copper foil 8 of C
, -For F4, each layer thick body connection point a, b.

Apply conductive adhesive 9 to the C part, and apply the conductive adhesive 9 to the other parts. After applying the green adhesive 10, they are laminated and heated under pressure to form four single-layer flexible printed wiring boards r1 to F.
4 and 2 are bonded together and cured.

In the above process, single-layer flexible printed wiring board F1
The method of exposing the copper foil 8 at the conductor connection points a, b, and c of ~F4 is that when manufacturing the substrates F1 to F4, the conductor connection points a, This can be achieved by making holes in advance at positions b and c. In addition, when using a normal single-sided steel-clad flexible board, holes are pre-drilled in the base film and conductor connection tubes Pfra, b
, c can be realized by removing the insulator (base film and adhesive layer) by laser processing or the like. However, when bonding and curing the single-layer flexible printed wiring boards F1 to F4 to each other, when using an adhesive that requires a higher curing temperature than the insulating adhesive 1o as the conductive adhesive 9, or using solder. When using a conductive adhesive such as paste, apply the thermocompression trowel shown at 11 in Figure 3 to the connection points a, b, and c (apply in the direction indicated by the arrow). Can be adhesively cured or soldered. In this case, since the copper foil 8 is exposed at the conductor connection points a, b, and c, the heat conduction of the thermocompression trowel 11 is good and bonding can be easily performed3. [Effects of the Invention] As described above. According to the present invention, the copper foil pattern of the single-layer flexible printed wiring board is exposed as a conductor connection point,
A conductive adhesive is applied to the conductor connection points, and an insulating adhesive is applied to the other parts (2).Multiple sheets of such single-layer flexible substrates (k>i) are layered and heated under pressure, and then bonded to each other. Since adhesive connection is used, a flexible multilayer printed wiring board can be manufactured at low cost and with good mass production.In other words, a single layer flexible printed wiring board with exposed copper foil can be manufactured at low cost and with good mass production. When connecting multiple layers, the copper foil is exposed at the conductor connection point and adhesive connection is achieved with good heat conduction.As a result, flexible multilayer printed wiring boards can be manufactured by simply repeating the process of applying adhesive and laminating pressure and heating. This is the result.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing a conventional through-hole plating connection method, Figure 2 is a cross-sectional view showing a through-hole connection method using silver paste coating, and Figure 3 is a process for manufacturing a flexible multilayer printed wiring board according to the present invention. It is a sectional view showing the method.F, -F4...Single layer flexible printed wiring board, a
, b, c... Conductor connection point, 7... Insulator film (insulating resin), 8... #I foil, 9... Conductive adhesive, 10... Insulating adhesive , 11...Thermocompression bonding iron.

Claims (1)

[Claims] A single-layer flexible printed wiring board was prepared in which the conductor portion 1c at the conductor connection point was exposed, and then a 4-conductivity liquid adhesive was applied to the conductor connection point, and an insulating adhesive was applied to the other parts. A flexible multilayer printed wiring board characterized in that the single-layer flexible printed wiring board is multilayered by laminating a plurality of single-layer flexible printed wiring boards and applying pressure and heat to conductively connect each conductor. manufacturing method.