JPS6030116B2 - printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide a plurality of conductor layers when using an inexpensive thermoplastic resin having soldering heat resistance as a substrate of a printed wiring board.

Conventionally, thermosetting resins such as phenol resins and epoxy resins have been mainly used as substrates for printed wiring boards.

In the case of double-sided printed wiring boards, the plating method was the most efficient and reliable method for connecting the front and back conductors, but for paper-based phenolic resin laminates, a copper plating layer was used to prevent expansion and contraction in the thickness direction. cannot be followed repeatedly, and there is a risk of wire breakage.Therefore, a glass cloth-based epoxy resin laminate is used. Glass cloth-based epoxy resin plates are also used for multilayer wiring boards, but the processing process is complicated and the cost is extremely high. For this reason, three or four layers are most often used, reducing the number of layers as much as possible, and the thickness is often 1.6 sails as standard, just like single-sided and double-sided boards. Heat-resistant thermoplastic resins such as tetrafluoroethylene and polyimide are available, but they do not have good adhesion to copper foil conductors or plating, and are even more expensive than glass cloth-based epoxy resins. Therefore, it is only used in circuits where flexibility is essential.

Although polyethylene terephthalate, which is commercially available as a thermoplastic resin in the form of a film, is inexpensive, it cannot be used as a substrate for printed wiring boards because it lacks solder heat resistance. Polyacetal resin is also unsuitable in terms of soldering heat resistance, and polycarbonate, polysulfone, polyphenylene oxide, etc. have problems with solvent resistance during processing, use, and after mounting, and are therefore unsuitable. Met. The present invention focuses on inexpensive polyethylene terephthalate resin, and uses polyester elastomers such as polybutylene terephthalate and polytetramethylene terephthalate resin, which have improved soldering heat resistance, to achieve flame retardant and This relates to a printed wiring board in which a multi-conductor layer is obtained using molding powder mixed with glass powder, quartz powder, silica, and asbestos at a maximum of 35% to improve mechanical strength, retention characteristics, and dimensional stability. The purpose is to provide an inexpensive printed wiring board.

That is, when processing the molding powder into an injection-molded plate, the parts corresponding to the holes of the wiring board are formed at the same time, thereby forming the base material and forming the holes at the same time, thereby shortening the manufacturing process of the wiring board. Streamline. It also contributes to resource conservation as the hole cut portion is not discarded. This base material is not deformed by contact with 260 qo1 top sand and molten solder for about 350 q02 seconds.
When forming the base material as a printed wiring board, prepare two perforated plates, form a conductor on each or both,
By rough bonding, a printed wiring board having multiple conductor layers can be obtained. Although an epoxy resin adhesive may be used as a bonding means, it is also possible to twill bond without an adhesive using a heat fusion method, which can further save resources. As a method of forming a conductor on a set of two perforated plates, copper foil is bonded using a known die stamping method.

Commercially available copper boxes are difficult to bond because they are lined with adhesives such as vinyl butyral, nitrile rubber, and phenol, and using epoxy resin adhesives reduces the expansion and contraction rate between the copper foil and the substrate. Due to the difference, even if the adhesion is good, warpage may occur on a 1.6-inch thick substrate, or cracks may occur on a 35-inch thick copper foil. Although it is possible to use polybutylene terephthalate resin as an adhesive, it may be more resource-saving to adhere without an adhesive. However, it is necessary to roughen the brocade surface of the part to be coated. In the case of 35mm steel foil, a concave surface with an average depth of 5 to 7.5 degrees is formed on one side, and on both sides of copper foil, a concave surface with an average depth of 3 to 5 degrees is formed.

When a known paper-based phenolic resin laminate is used as one of a set of two perforated plates, they are bonded together using an epoxy resin adhesive.

If prepreg is not available for the glass cloth base epoxy resin laminate, it is bonded together using an adhesive in the same manner. When using copper foil as a conductor, only one side of one plate,
Alternatively, copper foil may be formed on both sides, but only one side may be used for the other plate, and in some cases, no conductor may be formed at all. If the other plate is not formed with a conductor, the other plate serves as an electromechanical protection for the portion of the one plate where the back conductor is formed. Conductivity in the holes is necessary to electrically connect conductor layers on both sides or multilayer surfaces, and is a necessary technology for forming double-sided boards and multilayer boards. For the conductivity of the holes, it is possible to apply a technique of forming the holes by using a combination of chemical plating and electroplating, or using a thick rena technique of chemical plating. However, in the present invention, when conductive layers are formed on both sides of one plate, it is not necessary to expose the other plate to plating. Instead of the plating process, there is a method of measuring the electrical continuity of the hole using conductive paint, which is a dry method compared to the plating method, has higher reliability of through-hole connection than copper plating, and is made of inexpensive materials. It is more economical because a simplified process can be used. As for the method of applying conductive paint, if the thickness is 1.6 feet or more, conductive paint is applied to the pins. For example, use a metal pin with a diameter of 0.6 in the hole on the 1.0 diameter side, and insert a large number of metal pins into the hole on the 1.0 diameter side.
Dip the silver powder-epoxy resin paint called 504A to a depth of about 1 inch to adhere it, and wipe off the excess conductive paint with a plate with 1.2 holes in diameter.
．． Insert the enemy's hole and apply up and down movements 3 times with an amplitude of about 3 sides centering on the part where the conductive paint is attached. The conductive paint first adheres to the hole wall, then overflows as a land on one side of the printed wiring board, and then lands of the same shape can be formed on the other side of the printed wiring board by sandwiching the board. The conductive paint can be fixed in 30 minutes at 130 qo to 10 minutes at 15,000 qo. Adhesion between this type of conductive paint and polybutylene terephthalate resin is extremely good. Through-hole connections with conductive paint are further simplified and can be made by screen printing. That is, the pore diameter is 1.0
If the plate thickness is 0.8 ribs or less with respect to the side, a known screen printing method can be easily used. However, the mask is preferably a metal mask having openings corresponding to the holes in the printed wiring board, and the threads of the screen must not prevent the conductive paint from passing through the holes. Example 1 As a polybutylene terephthalate resin pellet, 3300 manufactured by Celanese Co., Ltd., USA, is used.

It contains 30% by weight glass powder. The mold is set so that a 0.8-thickness side and a 1.0-diameter hole for the lead wire and through hole are simultaneously obtained by injection molding. Injection pressure 750k9', mold temperature 240k
A molded plate 1 having a size of 10×20 and a first resin substrate was obtained using 00. The thickness of the first conductor layer is 3 for this molded plate 1.
A 5R single-sided assembled copper foil 3 can be bonded to the molded plate 1 with the phase forming side facing the molded plate 1 at a thickness of 5k9/ground in 1 to 2 seconds without an adhesive. Etching is then performed by known means. At this time, not only the circuit figure but also the portion forming the lid of the through hole 2 is removed by etching. Then, on the other side, 5504A from DuPont was printed as the second conductor layer, a silver powder-resin conductor 6, using a 220 mesh Tetron screen, and the same 5504A was printed as the through-hole conductor 7 with the copper foil conductor. Printed from the copper foil side using a metal mask with a thickness of 0.2 skin, each cost 130q030
It was heated and cured for 150 minutes and 150 minutes. Through-hole resistance was 7-9 milliohms. The resistance value of the copper foil conductor having a thickness of 35 peaks was 1 milliohm/square, and the resistance value of the silver powder-resin paint 7 was 8 to 9 milliohm/square. Finally, a molded plate 5 with holes on the 0.8-thick side for protection of the conductor using copper powder and resin paint, that is, a second resin substrate of the same shape that is not exposed to the copper foil.
is treated using the heating and pressurizing method. At this time, 5k9/enemy, 21
By placing them one on top of the other for 2 to 3 seconds under the condition of 0qo, they can be bonded together as an integral board. Example 2 A 0.8-thick paper-based phenolic resin laminate with a 35-thick copper foil attached on one side was used as the molded plate 1, which is the first resin base, and was molded by known means. Perform hole punching and selective etching to obtain conductors.

A molded plate of polybutylene terephthalate resin bait is prepared as the molded plate 5 which is the second resin base. Furthermore, an epoxy resin adhesive layer is printed as an adhesive by a screen method on the opposite side of the molded plate 1 from the surface on which the copper foil 3, which is the first conductor layer, is formed. Of the main surfaces of the molded plate 5, a silver powder-resin conductor 6, which is a second conductor layer, is placed on the surface that is to be bonded to the molded plate 1 in a circuit-like manner, mainly as a cross-over connection of the conductors of the molded plate 1. Print and cure with 150003mm. The molded plate 5 with the conductor attached was pasted with the epoxy resin adhesive layer printed on the molded plate 1, and 150q0
Complete curing adhesive in 30 minutes. A through-hole conductor 7 is printed using conductive paint in the through-hole 2 of the molded plate 1 that requires through-hole connection, and the copper foil 3 and the conductor of the molded plates 1 and 5 are connected through the through-hole wall. Connect with 6. The through-hole conductor 7 is cured at 150°C for 30 minutes. In this way, a printed wiring board having two conductor layers with the second conductor layer therein is obtained. If it is necessary to protect the conductive paint printed on the hole, a solder heat-resistant resin 8 such as a solder resist is further printed. As described above, the present invention can provide an inexpensive product by using a molded plate of polybutylene terephthalate or polytetramethylene terephthalate-based polyester elastomer as a resin base.

[Brief explanation of drawings]

The drawing is a block diagram showing an embodiment of the printed wiring board of the present invention. 1...Molded plate (first resin base), 2...Through hole, 3...
... Steel foil (first conductor layer), 5 ... Molded plate (second resin base), 6 ... Conductor (second conductor layer), 7
...Through-hole conductor.

Claims (1)

[Claims] 1. A first resin base having a through hole and made of polybutylene terephthalate and having a first conductor layer on one side, and the first conductor layer of the first resin base. A printed wiring board comprising: a second resin substrate bonded to the other side thereof; and a second conductor layer interposed between the first and second resin substrates. 2 As the second conductor layer, the second
2. The printed wiring board according to claim 1, wherein a conductive foil of copper, aluminum, iron, etc. is formed on a resin substrate. 3. The printed wiring board according to claim 1, wherein the first and second conductor layers are formed on both sides of the first resin substrate. 4 The second resin base is used to protect the second conductor layer.
4. The printed wiring board according to claim 3, wherein the printed wiring board is formed on a resin substrate. 5. The printed wiring board according to claim 1, characterized in that through-hole conductors are formed in the through-holes of the first resin substrate.