JPS592394B2 - printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printed wiring board made rigid by bonding a flexible wiring board to a supporting base plate, and particularly relates to a printed wiring board made of a rigid body by bonding a flexible wiring board to a support base plate, and particularly to a printed wiring board that uses an inexpensive film base for the flexible wiring board and resistors formed thereon. The purpose is to reduce losses due to poor yields of materials and conductors.

Generally, when forming resistors, conductors, etc. on printed wiring boards,
As shown in FIG. 1, a solderable conductive layer 2 is formed on one side of the printed wiring board 1, and a resistor 4 and a conductive layer 5 are printed on the other side of the printed wiring board 1. The resistor 4 was connected to the conductor layer 2 by forming a connecting conductor layer 7 in the through hole 6 provided in the through hole plating.

However, in the through-hole plating method, the plating solution permeates into the inner layer of the printed wiring board due to the plating bath, and the printed wiring board itself is likely to change in quality. A disconnection occurred in the wall due to thermal shock. Therefore, it has been necessary to use expensive materials such as glass cloth-based epoxy resin laminates, polyimide resin plates, and glass cloth-based polyimide resin laminates that have high soldering heat resistance as printed wiring boards. Although polyester film is advantageous in terms of cost, it has the disadvantage that it cannot support heavy components as a rigid body and is easily shrunk by solder baths. Furthermore, depending on the processing yield of elements such as resistors and conductors printed on the back side of ordinary single-sided printed wiring boards, the already completed single-sided printed wiring boards often become defective, increasing costs. This was a contributing factor. In addition, when applying silver paint to through-hole connections, there is a known method in which a pin coated with silver paint is used to attach it to the hole wall, and at the same time, lands are also formed on both sides of a single-sided printed circuit board. However, the formation state at the land portion is not constant, and there are disadvantages that the land portion may come into contact with an adjacent conductor on the wiring surface, or it may not be formed continuously between the hole wall and the wiring surface. The present invention eliminates such conventional drawbacks, and the present invention will be described below with reference to drawings of embodiments.

FIG. 2 shows an example of the configuration of the printed wiring board of the present invention, and in the figure,
Reference numeral 11 denotes a supporting base plate, which may be a glass cloth-based epoxy resin laminate, a glass matte epoxy resin laminate, a glass matte polyester resin laminate, a paper-based phenolic resin laminate, or the like.

A solderable conductor layer 12 is formed on one side of the support base plate 11 by a well-known method such as etching or die stamping, and through holes 13 for leads are formed in advance.
is formed. Reference numeral 14 denotes a flexible wiring board which is made rigid by being bonded to the support base plate 11, and a polyester film is used as the support base.

Then, a resistor 15 and a conductor layer 16 are formed on this polyester film by a known method such as a plating method, a screen printing method, or a sputtering method. Here, the flexible wiring board 14 has a resistor 15 formed thereon.
The conductor layer 16 is bonded to the surface of the support base plate 11 on which the conductor layer 12 is not formed so as to close one opening of the through hole 12 so that the conductor layer 16 is installed internally. Reference numeral 17 is provided in the through hole 12 of the support base plate 11 and is connected to the flexible wiring board 1.
4 is a connecting conductor layer for joining the resistor 15 provided in the support base plate 11 to the conductor layer 12 of the support base plate 11, and is formed by a well-known method such as a screen printing method or an offset printing method.

Example A paper-based phenolic resin laminate with copper foil coated on one side was used as a hard substrate, a conductive layer was formed on one side by a known etching method, and through holes were formed by a punching method. Prepare a single-sided printed wiring board.

On the other hand, a polyester film was used as a support base, and a resistor was used on one side of the polyester film as a resistor.
゛13, RS150-14 carbon-resin resistance paint was printed by a known screen printing method, and as electrodes and general wiring, 5504A conductive paint from DuPont, USA was printed by a known screen printing method. death,
15 Prepare a flexible wiring board that has been cured under C6O conditions. The screens used at this time were 160 mesh silk for resistors and 220 mesh Tetron screens for conductors. Further, on the printed surface of the resistor, an epoxy resin-based protective coating prepared by mixing 100 parts of bisphenol-based epoxy resin and 20 parts of hymetic acid anhydride as a hardening agent is printed using a 160 mesh silk screen. Next, the resistor-printed side of the flexible wiring board was made to face the back side of the single-sided printed wiring board mentioned above, and a 5k9/CT
The 150 pieces were heated for 30 minutes under a pressure of 150 C to cure the adhesive and complete the adhesion so as to close one opening of the through hole. The adhesive strength of this part was 0.0 at 2600C.
It was over 3k9/Zui. Finally, conductive paint is printed using a metal mask from the conductor side of the single-sided printed wiring board to the hole wall of the through hole and the hole bottom formed by the printed element such as a resistor or conductor or its electrode. , 15 'Cure and fix under conditions of C3O content. In this way, normal insulation on the back side is maintained as a single-sided printed wiring board, and a second
A resistive circuit board can be obtained that includes a conductive layer or a resistive element and is connected to one side of the single-sided printed wiring board by a printed bottomed through-hole connection. Result of solder bath: 2600
Even after being immersed in a solder bath for 5 seconds at C20 seconds, neither peeling between the adhesive layers nor shrinkage of the polyester film occurred. In addition to the above embodiments, a flexible wiring board using a polyester film as a support base may be formed individually for each resistor and bonded to a single-sided printed wiring board. It may also be a multi-layer board.

As described above, according to the present invention, the film is heated at 260°C and 20°C.
The resistor is printed on an inexpensive film base and bonded to the support base, giving it a soldering heat resistance of seconds, so if the resistor is defective, it can be repaired by replacing the film base. It has the advantage that loss can be reduced, and the value of the resistor is stabilized because the resistor and conductor layer are internalized and are not directly exposed to the outside air or soldering flux.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional printed wiring board, and FIG. 2 is a sectional view showing an example of the structure of the printed wiring board of the present invention. 11...Support base plate, 12...Conductor layer, 13...Through hole, 14...Flexible wiring board, 15...Resistance Body, 16...
1 conductor layer, 17... conductor layer for connection.

Claims (1)

[Claims] 1. The above-mentioned flexible wiring is equipped with a flexible wiring board in which a resistor or a conductor layer is formed on a polyester film as a support base, and a support base plate with a solderable conductor layer on one side and through holes in required places. A plate is adhered to the surface of the supporting base plate on which the conductive layer is not formed so as to close one opening of the through hole, and the printed through hole connection conductor layer provided in the through hole is used to connect the flexible wiring. A printed wiring board characterized in that a resistor or a conductor layer of the board and a conductor layer of the support base plate are electrically connected.