JPS61256794A - 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 [Industrial Field of Application] The present invention relates to a printed wiring board constructed in a laminated manner.

[Conventional technology]

Conventionally, printed resistors are formed between adjacent wiring layers on a substrate,
Thick film circuits, in which lead frames for external connections are provided at the ends of the substrate, are used in various areas.

[Problem that the invention seeks to solve]

However, such conventional circuits have hard substrates and
In addition, since it is thick, it is difficult to form a laminated structure, which has the disadvantage that the larger the circuit scale, the larger the space it occupies.

[Means for solving problems]

In order to solve these drawbacks, the present invention forms a printed resistor on a flexible printed circuit board, laminates these seven flexiple printed circuit boards, and reinforces this with a reinforcing plate.

[Effect]

Because it is layered, high-density circuits can be formed in a small space.

〔Example〕

FIG. 1 is a cross-sectional view showing an embodiment of the invention, in which 1 is a hard reinforcing plate and 2 is a 7-lexiple printed circuit board.

The flexible printed circuit boards 2 are formed in a laminated manner with an adhesive layer 3 interposed therebetween. and second wiring layer 2ct 2a +, underlay layer 2e1 wiring layer 2c formed to reach wiring layer 2dt from wiring layer 2c
From the silver electrodes 2f and 2r provided on t2a, the underlay layer 2 so as to reach from the silver electrode 2f to the silver electrode 2f, the printed resistor 2hs formed on the overlay layer 21 formed so as to cover the printed resistor 2h. It is configured. Then, the laminated flexible printed circuit board is bonded, l11
The flexible printed circuit board is bonded to the reinforcing plate 1 via the reinforcing plate 1, and the m part t- of the flexible printed circuit board extends outward from the end of the reinforcing plate 1.

In the printed wiring board configured in this way, the thickness of the flexible printed circuit board is thin (the thickness is enlarged in Figure 1 to show the structure), it can be easily formed into a laminated structure, and it is easy to mount. It takes up less space. Since the flexible printed circuit board 2 extends outward from the reinforcing plate 1, the wiring layer 2d in the extended portion can be used for external connection. In order to do this, a conventional connection method may be used in which the flexible printed circuit board 2 and the lead frame are connected at the end of the reinforcing plate 1.

Figure 2 shows an overlay layer 21 used at the overlapped portion of a flexible printed circuit board 20 with an adhesive layer 3 and a base film 2.
b, and further, a part of the flexible printed circuit board 2 of each layer is pulled out to the end of the reinforcing plate 1, and a lead frame (not shown) is connected thereto.

With this structure, the process is simplified because the overlay layer 21 shown in FIG. 1 does not need to be formed.

In FIG. 3, a copper terminal 5 for connecting a lead frame is provided on the reinforcing plate 1, and a lead-out part 2j for external connection is protruded from the flexible printed circuit board 2, and the copper terminal 5 and the lead-out part 2 are made to protrude from the flexible printed circuit board 2.
are connected by silver paste 6. The structure constructed in this way has better heat resistance stability with respect to the electrode for connecting the lead frame than the structure shown in FIG. Note that the copper terminal 5 is not just a lead-out electrode, but may be a part of a pattern.

In FIG. 4, the lead-out portion 2j is omitted, and the copper terminal 5 and each flexible printed circuit board 2 are directly connected with the silver paste 6.

Although the printed resistor provided on the board cannot be trimmed with the board having the laminated structure as described above, for example, as shown in FIG.
By providing a printed resistor 7 and trimming the printed resistor 7, it is possible to correct the printed resistor 2h in the lower portion where the flexible printed circuit board 20 is overlapped. In FIG. 5, 8a is a base film, 8b is a copper electrode, 8c is a silver electrode, and the adhesive layer, underlay layer, and overlay layer are omitted.

〔Effect of the invention〕

As explained above, in this invention, the flexible printed circuit board on which printed resistors are formed has a laminated structure.
This has the effect that high-density packaging and thin construction, which could not be achieved in the past, can be easily achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the invention, and FIGS. 2 to 5 are perspective views showing other embodiments. 111...Reinforcement plate, 2...Flexible printed circuit board, 2m, 3.4...Adhesive layer, 2b...Fist/base film, 2e12d@@...Wiring layer, 2e...
... Underlay layer, 2f, 22... Silver electrode, 2h.
...Printed resistance, 21 ...Overlay layer.

Claims (1)

[Claims] It is composed of a reinforcing plate and a flexible printed circuit board formed in a laminated manner on the reinforcing plate, and each flexible printed circuit board has a base film and a first and second circuit board that are adhered adjacent to each other on one side of the base film. Second
an underlay layer formed to reach from the first wiring layer to the second wiring layer, first and second electrodes provided in the first and second wiring layers, respectively; A printed wiring board comprising a printed resistor formed on an underlay layer from one electrode to a second electrode.