JPS62210693A - Circuit module with built-in capacitor - 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 circuit module, and particularly to a circuit module that incorporates a capacitor element in an inner layer and is thinned by multilayer wiring.

[Technical background of the invention and its problems]

BACKGROUND ART In recent years, electronic devices have rapidly become smaller and more multifunctional, and as a result, components have become smaller and thinner, and circuits have become more complex, making it difficult to wire them on the same plane. Multi-layer wiring includes thick film printing, green sheet multi-layer, through-hole multi-layer, etc., each of which is being put into practical use. As a result, the circuit module can be further downsized. Recently, as such a circuit module, a multilayer wiring circuit module in which a capacitor ceramic sheet is laminated within a green sheet multilayer wiring layer has been proposed. An example of this is shown in FIG. Using a slurry mainly composed of alumina powder, an organic binder, and a solvent, a sheet (7) of 50 to 500 μm is formed using a doctor blade,
Wiring is formed using tungsten conductor paint (9). The sheet that becomes the capacitor is a ceramic sheet (
Electrodes (8) are arranged on both sides of 7). A plurality of these sheets are laminated, pressure bonded, and then fired at a temperature of 1300° C. to 1600° C. to obtain a ceramic multilayer substrate with a built-in capacitor. However, this substrate has the essential drawbacks of multilayer green sheets, namely, the process is high temperature, which increases the cost, the thickness of a single sheet has a voltage limit, and mechanical strength is required. Therefore, a thickness of 100 μm or more is usually required, and as the number of laminated layers increases, there is a drawback that the overall burden increases. Furthermore, looking at the characteristics of a capacitor, the current visiting rate of alumina, which is a green sheet material, is approximately 8, and as mentioned above, the thickness of the layer cannot be made even thinner, so the capacitance per element is relatively small, 1000pF Katsura. The degree was the limit.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a circuit module with a built-in capacitor that has a simple product process, is low cost, and is suitable for thinning.

[Summary of the invention]

The present invention provides a multilayer printed wiring board in which a plurality of unit wiring sheets each consisting of a thermoplastic base material and a conductive wiring pattern formed on one or both sides of the base material are stacked and integrally formed.
This is a circuit module in which a g-electric film is laminated on the inner layer of the wiring board, and electrodes are arranged on both sides of the dielectric film.

The present invention will be explained in more detail with reference to the drawings. FIGS. 1A to 1C show examples of manufacturing a circuit module with a built-in capacitor according to the present invention. FIG. 1(a) shows an insulating base material (1) made of thermoplastic resin molded into a sheet, and through holes (2) are provided in advance in this base material. A conductive paste is printed and dried on this substrate (1) to form the upper electrode of the capacitor and the wiring J-. Similarly, a wiring sheet with a lower electrode (5) of a capacitor printed thereon is formed on a thermotransportable substrate (6), and a dielectric film is placed on the inner layer.

Here, the wiring layer (3), (41 is the thermoplastic base material fil
Although the example in which the dielectric film is applied is shown in (6) to (6) above, wiring may be formed on both sides of the dielectric film.

Alternatively, holes may be formed in the dielectric sheet in advance, and the holes may be processed so that they can be connected to each other by sandwiching the dielectric sheet. Specific examples of the thermoplastic base material for the unit wiring sheet used here include polyvinyl chloride, polystyrene, saturated polyester resin, polyethylene, polypropylene, polycarbonate, polyphenylene oxide, polysulfone, polyphenylene sulfide, polyacetal, polyamide, and the like. On the other hand, the conductor paste for wiring is prepared by mixing the above-mentioned thermoplastic organic resin or other thermoplastic resin as a binder with metal powder, and if necessary, a solvent is added as appropriate. Iron for metal powder.

Any of copper, nickel, gold, platinum, aluminum, etc. may be used, but copper and silver are suitable in consideration of conductivity and transmissibility.

The above-mentioned thermoplastic resins can be used as the electric film for the capacitor, but polyphenylene sulfide, polybutylene terretalate, polyethylene terretalate, and polycarbonate are particularly suitable for easily forming a thin film with high strength and heat resistance. Resin etc. are suitable.

Next, a plurality of the unit wiring sheets and the electric sheet obtained as described above are laminated as shown in FIG. 1(b), and they are heat-pressed using a hot press. The temperature, pressure, and pressurizing time of the hot press vary depending on the resin material used, and the conditions are selected as appropriate.

By this heating and pressure bonding, each unit wiring sheet and dielectric sheet are integrally molded as shown in FIG. 1(C), and the final conductor pattern including electrical connections in the through holes is simultaneously formed. In this case, since the conductor paste is made of thermoplastic resin, the conductor patterns on the upper and lower unit wiring sheets are heat-fused together by heat-pressing, and electrical contact is reliably formed. Furthermore, if a base material with a higher thermal deformation temperature than the unit wiring sheet is used for the dielectric film for capacitors, the dielectric film for capacitors will not undergo thermal deformation during heating and pressure, and will maintain its initial dielectric properties. This is preferable because it allows the maintenance of

[Effects of the Invention] According to the present invention, a plurality of wiring sheets on which conductor wiring patterns are formed in advance and a dielectric film are prepared,
By heat-pressing molding these, it is possible to integrally form a multilayer circuit board with a built-in capacitor.
Compared to the conventional green sheet type capacitor-embedded substrate, the dielectric thickness can be made thinner, so capacitors of 1000 pF or more can be easily formed. Furthermore, since integral molding and multilayering are performed by heat and pressure bonding, the overall thickness can be made extremely thin, and the complicated process associated with interlayer wiring can be omitted.

[Embodiments of the invention]

Thickness 100 μm 1 external size 50 ff as a thermoplastic base material
A polycarbonate sheet of lI1)×60ffiIm was used, and a through hole of 015 wφ was formed at a predetermined position. On one side of this thermoplastic insulating base material, polyvinyl chloride was used as a binder, and a conductive paste prepared by kneading silver powder and a solvent into the following composition was printed.

Conductor paste composition Vinyl chloride-vinyl acetate copolymer (vinyl acetate ratio 2
0chi) 210 parts by weight Silver powder (particle size 3μ): 90 parts by weight Solvent (mixed solvent of cyclohexanone 2-butylcarpitol) 290 parts by weight Next, the solvent was removed from the printed conductor paste by drying at 80°C for 20 minutes. , print the same conductive paste on the other side of the base material and use it as the upper electrode of the capacitor, 5x5m, 10x10
An electrode pattern of 20×20 mm was formed. Next, as a dielectric film, a 25 μm thick P film with through holes was prepared.
P5 (polyphenylene sulfide: KPS manufactured by Kureha Chemical Co., Ltd.
) was prepared.

Next, as a lower electrode, a 40×50 mm lower electrode pattern was printed on a polycarbonate resin sheet using the conductive paste described above. These four unit wiring sheets were laminated as shown in Figure 1(b), thermocompression bonded using a tabletop heat press with a heater temperature of 150°C, resin 20#/- and a holding time of 5 minutes, and then cooled directly. I took it out. On the upper surface of the obtained substrate, the lower electrode of the capacitor was exposed through a through hole in the dielectric film by pressing, making it possible to perform electrical measurements. Here, the capacity of the three patterns is Y
The results of measurement using an HP LRC meter at a measurement frequency of IMHz were as follows.

Further, the total thickness was about 200μ, and the reliability of the connections including through holes was good with no abnormalities observed after 200 cycles of -40°C to +60°C.

[Brief explanation of drawings]

FIG. 1 shows a diagram for explaining a circuit module with a built-in capacitor according to the present invention, and FIG. 2 shows a green sheet type capacitor-built-in board according to the prior art. 1... Thermoplastic base material, 2... Through hole, 3... Wiring pattern (upper electrode pattern), 4...
Dielectric film, 5... Lower electrode pattern, 6... Thermoplastic base material, 7... Alumina, 8... Electrode, 9... Paste agent, patent attorney Norihiko Ken Yudo Kikuo Takehana

Claims (3)

[Claims] (1) In a multilayer printed wiring board that is integrally formed by stacking a plurality of unit wiring sheets consisting of a thermoplastic insulating base material and a conductor wiring pattern formed on one or both sides of this base material, the inner layer of the wiring board A circuit module with a built-in capacitor, characterized in that dielectric films are laminated and electrodes are arranged on both sides of the dielectric films. (2) The circuit module with a built-in capacitor according to claim 1, wherein a dielectric film having a higher thermal deformation temperature than the thermoplastic base material used for the wiring sheet is used as the electric film. (3) A circuit module with a built-in capacitor according to claim 1, wherein a polyphenylene sulfide resin film is used as the dielectric film.