JP2007201065A - Substrate with built-in capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid a dielectric oxide coat of a plate-like electrolytic capacitor element from partially damaged by filling a gap between the circuit board in a built-in substrate and the plate-like electrolytic capacitor element with a gap filler, before pressurizing and heating for curing after stacking a copper foil and a semi-cured insulating base material such as prepreg from above the plate-like electrolytic capacitor element. <P>SOLUTION: The plate-like electrolytic capacitor element comprises a plate-like valve action metal, a positive electrode drawer 2 provided to one end of the valve action metal, and a negative electrode 3 in which a dielectric oxide coat layer 4, a solid electrolytic layer 6, and a conductor layer are sequentially stacked on the surface of at least the other end. The substrate with a built-in capacitor incorporates it in a printed wiring board. A gap is filled with a gap filler between the circuit board in the built-in substrate of which the plate-like capacitor element is mounted and the plate-like electrolytic capacitor element. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a capacitor built-in substrate. In particular, the present invention relates to a capacitor built-in substrate in which a flat electrolytic capacitor element is built.

  To incorporate a flat capacitor element in a printed wiring board, for example, a flat valve metal, an anode terminal provided at one end of the flat valve metal, and at least the surface of the other end In the case of a plate-like electrolytic capacitor element having a dielectric oxide film layer and a cathode terminal portion on which a solid electrolyte layer is successively provided, for example, FIG. 8 of Japanese Patent Application Laid-Open No. 2004-221534. As described in the above, after applying a conductive adhesive to a predetermined pad of a prepared circuit board, a flat electrolytic capacitor element is mounted, and then a semi-cured insulating base material such as a prepreg and After laminating the copper foil, it was cured by applying pressure and heating, and then the capacitor built-in substrate was manufactured while processing the copper foil into a circuit pattern by etching or the like.

JP 2004-221534 A

By the way, the flat electrolytic capacitor element has a shape structure in which the cathode terminal side is larger than the anode terminal part side, and when the flat electrolytic capacitor element is mounted on the circuit board, Since a gap is formed between the anode terminal portion and the cathode terminal portion, a semi-cured insulating base material such as a prepreg and a copper foil are laminated on the above plate-like electrolytic capacitor element and then heated under pressure. When cured, bubbles remain in the gap portion, or the gap portion is crushed and at the same time the gap portion of the plate electrolytic capacitor element is crushed downward and deformed, thereby causing the dielectric of the plate electrolytic capacitor element. The body oxide film is partially damaged.
Further, in the case of manufacturing the above-described flat electrolytic capacitor element, before providing the solid electrolyte layer, in order to separate the anode terminal portion and the cathode terminal portion so that the solid electrolyte layer does not cover the anode terminal portion, If a fluorine-based or silicon-based water / oil repellent is provided on the surface, it becomes difficult to fill the gap filler.

In order to solve the above problems, a flat valve metal, an anode terminal provided at one end of the valve metal, a dielectric oxide film layer at least on the surface of the other metal, and a solid electrolyte thereon In a capacitor-embedded substrate in which a flat electrolytic capacitor element comprising a cathode terminal portion sequentially provided with a conductor layer is built in a printed wiring board, the flat capacitor element is mounted and mounted A capacitor-embedded substrate is provided in which a gap between a circuit board in the built-in substrate and the flat electrolytic capacitor element is filled with a gap filler.
Also, a flat valve action metal, an anode terminal provided at one end of the valve action metal, a dielectric oxide film layer on the surface of at least the other end, a solid electrolyte layer thereon, and a conductor layer thereon A circuit board in the built-in substrate on which the plate-like electrolytic capacitor element is mounted and mounted on the plate-like electrolytic capacitor element in which the plate-like electrolytic capacitor element is built in the printed wiring board. And the flat electrolytic capacitor element are connected using a conductive material, the conductive material protrudes from or just before the flat electrolytic capacitor element, and the circuit board and the flat electrolytic capacitor It is an object of the present invention to provide a capacitor built-in substrate characterized in that a gap between the capacitor element is filled with a gap filler.

After laminating a semi-cured insulating base material such as a prepreg and a copper foil from above the flat electrolytic capacitor element, before curing by pressurizing and heating, the circuit board in the built-in substrate and the flat electrolytic capacitor element Since the gap between the gaps is filled with the gap filler, bubbles remain in the gap, or the gap is crushed and at the same time the gap of the flat electrolytic capacitor element is crushed down and deformed. Therefore, the dielectric oxide film of the flat electrolytic capacitor element is not partially damaged.
In addition, if the conductive material for conduction between the circuit board and the flat electrolytic capacitor element in the built-in substrate protrudes from the flat electrolytic capacitor element or is just before protruding, the fluorine material is interposed between the anode terminal part and the cathode terminal part. Even if a water- and oil-repellent body of silicon or silicon is provided, the gap filler is not easily filled.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following examples.
FIG. 1 shows a cross-sectional view of a flat electrolytic capacitor element.
Reference numeral 1 denotes a valve metal, which is a flat foil made of aluminum having a thickness of about 20 μm to 200 μm. One end side is the anode lead-out portion 2 side, and the other end portion side is the cathode portion 3 side. At least the cathode portion 3 side of the valve metal 1 is roughened by electrolytic etching or the like, and a dielectric oxide film layer 4 is provided on the surface. In general, since the valve metal 1 is cut out from a foil having a large area, the entire surface thereof is roughened.
A water / oil repellent body 5 is provided at the boundary of the anode lead-out portion 2 side and the cathode portion 3 side so as to be easily separated, and is obtained by curing a fluorine-based or silicon-based liquid resin. If the boundary portion is an etched portion, the resin penetrates into the pores of the etched portion of the valve metal 1 immediately after printing and is then cured by heating or the like. Further, when an elastomer type resin is used, it becomes a buffer material for stress when incorporated into the printed wiring board or after incorporation.
A solid electrolyte layer 6 is provided on the surface of the dielectric oxide film layer 4 on the cathode portion 3 side, and a cathode conductor layer 7 in which a carbon layer and a silver paste layer are laminated is provided on the surface.

FIG. 2 shows a cross-sectional view of a capacitor built-in substrate in which the above-mentioned plate-like electrolytic capacitor element is built.
The capacitor built-in substrate of the present invention is provided with at least a flat electrolytic capacitor element and a pad 9 for electrical connection on a prepared circuit board 8, and a conductive material such as a conductive adhesive or solder paste is provided on the pad 9. 10 is applied, a flat electrolytic capacitor element is mounted, then a gap filler 11 is filled in a gap portion between the circuit board 8 and the flat electrolytic capacitor element, and then semi-cured like a prepreg. After the insulating base material 12 and the copper foil 13 are stacked, the insulating base material 12 and the copper foil 13 are laminated by pressing and heating, and then the copper foil 13 is formed into a line pattern by etching or the like.

The gap filler 11 is preferably made of a resin such as an epoxy resin, and is preferably filled with a filler such as silica, alumina, boron nitride, aluminum nitride, silicon nitride, magnesia, magnesium silicate. (° C.) is 10 Pa · s or less, the filler diameter is 5 μm (maximum 20 μm) or less, and the thermal expansion coefficient α1 is preferably 40 ppm / ° C. or less. Powders such as silicone rubber and gel, thermoplastic resin composed of methyl methacrylate-butadiene-styrene, and the like may be added as a stress reducing agent.
The gap filler 11 is dispensed into a gap portion between the circuit board 8 and the electrolytic capacitor element, that is, at one side of the gap portion surrounded by the anode and cathode of the mounted electrolytic capacitor element and the circuit board 8. Is applied on the circuit board 8 and heated, so that the gap between the circuit board 8 and the electrolytic capacitor element is infiltrated and filled using the capillary phenomenon. At this time, if it is applied to two sides of the gap portion between the circuit board 8 and the electrolytic capacitor element, air is confined in the gap and it is difficult to fill the filler to the details.
At this time, if the water / oil repellent body 5 is present, the heated and low viscosity gap filler penetrates into the gap between the circuit board 8 and the electrolytic capacitor element by the water / oil repellent body 5. Filling may be hindered. The gap filler 11 that has been prevented from penetrating travels along the edge of the electrolytic capacitor element, reaches the opposite surface to which the gap filler of the electrolytic capacitor element is applied, and closes the entrance of the gap. In this case, it is difficult to fill the gap no matter how much gap filler is added.
In order to prevent this, the conductive material 10 may protrude from the electrolytic capacitor element or immediately before it protrudes.

FIG. 3 shows a top view of the conductive material 10 as to whether it protrudes from the electrolytic capacitor element or immediately before it protrudes.
Reference numeral 14 denotes the location of the gap filler inlet. The conductor 10 is disposed so that the gap filler injected from the injection port is repelled by the water / oil repellent body 5 and wraps around the opposite surface along the ridge of the electrolytic capacitor element. In FIG. 3 (a), the gap filling material applied to the injection port 14 is easy to enter the gap surrounded by the anode and cathode of the electrolytic capacitor element and the circuit board 8, and the anode and cathode of the electrolytic capacitor element. All the gaps other than the gap part surrounded by the circuit board 8 are blocked by the conductive material 10 so as to protrude from the electrolytic capacitor element, and the gap filler surrounded by the anode and cathode of the electrolytic capacitor element and the circuit board 8 is filled. Is the shape that is most easily filled.
Further, in order to prevent the gap filler from being transmitted to the flange of the electrolytic capacitor element and wrapping around the opposing surface, the electrolytic capacitor should be stopped at any one location by the opposing surface. Since the conductive material 10 has only to be disposed in the gap between the element ridges and the circuit board 8, the structures as shown in (b) to (h) may be used. In addition, this invention is not limited to a following example. Further, it is desirable that this protruding area be within the range of the mounting pads on the circuit board, but if there is no risk of short circuit, it may be outside the mounting pads.

An aluminum foil having a thickness of 60 μm was prepared as a valve metal, and the surface thereof was roughened by electrolytic etching. The roughening was performed by applying an alternating current to the aluminum foil. The thickness of the roughened layer was about 20 μm. Next, in order to form a dielectric oxide film with a thickness of several nanometers on the surface of the valve metal on the cathode side of the aluminum foil, the above-mentioned solution was added to an aqueous solution of ammonium adipate (liquid temperature 60 ° C.) having a concentration of 5%. An aluminum foil was put in and formed by performing constant voltage formation with a formation voltage. Fluorine-based liquid resin is printed in the width of 0.1 to 0.5mm as a water- and oil-repellent body at the boundary between the cathode part and anode lead part of the valve metal so that the anode part and cathode part can be easily separated. It was heat cured.
Next, the cathode part of the valve action metal was immersed in a solution containing a polythiophene monomer, an iron-based oxidant, and a dopant, and a solid electrolyte layer was formed by chemical polymerization. Then, a carbon paste was applied to the solid electrolyte layer and heat treated to form a carbon layer. Further, an Ag paste is applied to the surface of the carbon layer to form an Ag paste layer, and a cathode conductor layer composed of the carbon layer and the Ag paste layer is formed. The outer shape is 2 × 3 mm and the thickness is about 0.1 mm. A solid electrolytic capacitor element was produced.
The obtained electrolytic capacitor element was mounted by printing a conductive adhesive on the surface of the circuit board pad using a metal mask, placing the electrolytic capacitor element on the printed conductive adhesive, and then 150 ° C. The heat treatment was performed for 60 minutes.
Next, on the side of the gap between the anode and cathode of the mounted electrolytic capacitor element and the circuit board, using a dispenser, apply a gap filler to the circuit board, heat it, The gap between the cathode and the circuit board was infiltrated to fill the gap.
After that, prepreg and copper foil are laminated on the circuit board on which the above plate-like electrolytic capacitor element is mounted, and then cured by applying pressure and heat. Finally, the copper foil is etched to form a circuit, and the capacitor is built in. A board was produced.

It is sectional drawing of the electrolytic capacitor element which concerns on this invention. It is sectional drawing of the board | substrate with a built-in capacitor | condenser incorporating the electrolytic capacitor element which concerns on this invention. It is a top view of the condition of whether the conductive material which concerns on this invention protrudes from an electrolytic capacitor element, or is just before protruding.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Valve action metal, 2 ... Anode extraction part, 3 ... Cathode part, 4 ... Dielectric oxide film layer, 5 ... Water / oil repellent body, 6 ... Solid electrolyte layer, 7 ... Cathode conductor layer, 8 ... Circuit board , 9, pads, 10, conductive material, 11, gap filler, 12, insulating substrate, 13, copper foil, 14, injection port, 15, a portion where the conductive material protrudes, and 16, a portion immediately before the conductive material protrudes.

Claims (2)

  A flat valve action metal, an anode lead part provided at one end of the valve action metal, a dielectric oxide film layer on the surface of at least the other end, and a solid electrolyte layer thereon, and a conductor layer thereon A circuit board and a flat plate in the built-in board on which the flat electrolytic capacitor element is mounted, wherein the flat electrolytic capacitor element comprising the cathode portion is provided in a printed wiring board. A capacitor-embedded substrate, wherein a gap between the electrode-shaped electrolytic capacitor element is filled with a gap filler. A flat valve action metal, an anode lead part provided at one end of the valve action metal, a dielectric oxide film layer on the surface of at least the other end, and a solid electrolyte layer thereon, and a conductor layer thereon In a capacitor-embedded substrate in which a flat electrolytic capacitor element composed of a provided cathode portion is built in a printed wiring board,
The circuit board in the built-in substrate to be mounted with the flat electrolytic capacitor element mounted thereon and the flat electrolytic capacitor element are connected using a conductive material;
The conductive material is protruding from the flat electrolytic capacitor element or just before protruding;
A capacitor-embedded substrate, wherein a gap between the circuit board and the flat electrolytic capacitor element is filled with a gap filler.

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