JP2007273502A - Solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor for suppressing deterioration in electrical characteristics. <P>SOLUTION: In the solid electrolytic capacitor 10, distortion caused by stress is reduced significantly even if the stress is caused between a substrate 14 and a resin mold 16 by a shock absorbing film 60 interposed between the resin mold 16 and the substrate 14. As a result, the separation is restrained between the substrate 14 and the resin mold 16 caused by the stress, and the adhesion force is reinforced between the substrate 14 and the resin mold 16, thus suppressing the deterioration of electrical characteristics generated by the separation of the resin mold 16 from the substrate 14 in the solid electrolytic capacitor 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid electrolytic capacitor.

In general, capacitor elements used in solid electrolytic capacitors use a metal (so-called valve metal) such as aluminum, titanium or tantalum having an insulating oxide film forming ability as an anode, and anodize the surface of the valve metal to insulate it. After forming the conductive oxide film, a solid electrolyte layer made of an organic compound or the like substantially functioning as a cathode is formed, and a conductive layer such as graphite or silver is further provided as the cathode. As such a solid electrolytic capacitor, for example, Patent Document 1 below discloses a solid electrolytic capacitor of the type in which the capacitor element is mounted on a substrate and a resin mold is applied thereon.
JP 62-52451 A

  However, in the above-described conventional solid electrolytic capacitor, the adhesive force between the resin mold and the substrate is reduced due to the environment used, etc., and moisture and air enter from the interface, and the electrical characteristics of the capacitor are remarkably increased. It sometimes deteriorated.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a solid electrolytic capacitor in which deterioration of electrical characteristics is suppressed.

  A solid electrolytic capacitor according to the present invention is connected to a capacitor element having an anode part and a cathode part, and to an element mounting area of an element mounting surface on which the capacitor element is mounted, to an anode pattern and a cathode part connected to the anode part. And a resin mold that integrally covers the substrate with the capacitor element, and the substrate is provided with a buffer film in an outer peripheral region of the element mounting region. A buffer film is interposed between the two.

  In this solid electrolytic capacitor, even when stress occurs between the substrate and the resin mold due to the buffer film interposed between the resin mold and the substrate, distortion caused by the stress is significantly reduced. Yes. Therefore, peeling between the substrate and the resin mold due to stress is suppressed, and the adhesion between the substrate and the resin mold is enhanced. Therefore, in the solid electrolytic capacitor according to the present invention, the deterioration of electrical characteristics caused by the resin mold peeling from the substrate is suppressed.

  Moreover, the aspect which has a thermal expansion coefficient between the thermal expansion coefficient of a board | substrate and the thermal expansion coefficient of a resin mold may be sufficient as a buffer film. In this case, the buffer film suppresses the stress caused by the thermal expansion deviation between the substrate and the resin mold. Therefore, peeling between the substrate and the resin mold can be more effectively suppressed, and the adhesion can be further strengthened.

  Further, the buffer film may be provided in the entire remaining area of the element mounting area where the anode pattern and the cathode pattern are formed. In this case, the adhesion between the substrate and the resin mold is further strengthened.

  Moreover, the buffer film may be made of resin. Furthermore, the resin constituting the buffer film may contain a filler. When the filler is contained in the resin, the adhesion area of the buffer film is expanded, and the adhesion force with the resin mold is enhanced.

  ADVANTAGE OF THE INVENTION According to this invention, the solid electrolytic capacitor by which deterioration of the electrical property was suppressed is provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments that are considered to be the best in carrying out the invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps.

  FIG. 1 is a perspective view showing an electrolytic capacitor according to an embodiment of the present invention. As shown in FIG. 1, the solid electrolytic capacitor 10 includes a capacitor element 12, a rectangular flaky substrate 14 on which the capacitor element 12 is placed, and a resin mold 16 that molds the capacitor element 12 and the substrate 14. Yes.

  The capacitor element 12 is a two-terminal type capacitor element having one anode portion 24 and one cathode portion 28, and is a foil-shaped capacitor whose surface is roughened (surface enlarged) and subjected to chemical conversion treatment. A solid polymer electrolyte layer and a conductor layer are sequentially laminated on a partial region (described later) on an aluminum substrate (valve metal substrate). More specific description will be given with reference to FIG. FIG. 2 is a schematic cross-sectional view showing a main part of the solid electrolytic capacitor 10 shown in FIG. As shown in FIG. 2, an aluminum substrate 18 roughened by etching has an insulating aluminum oxide film 20 formed on its surface 18a by chemical conversion treatment, that is, anodic oxidation. Then, a solid polymer electrolyte layer 21 containing a conductive polymer compound is impregnated in the recessed portion of the aluminum substrate 18 whose surface has been enlarged. The solid polymer electrolyte layer 21 is formed by impregnating the recesses of the aluminum substrate 18 in the monomer state, and then chemical oxidation polymerization or electrolytic oxidation polymerization.

  On this solid polymer electrolyte layer 21, a graphite paste layer 22 and a silver paste layer 23 (conductor layer) are sequentially formed by any one of a screen printing method, a dipping method (dip method), and a spray coating method. The solid polymer electrolyte layer 21, the graphite paste layer 22 and the silver paste layer 23 constitute a cathode electrode of the capacitor element 12.

  As shown in FIG. 1, the capacitor element 12 has a rectangular flake-like shape, and includes an anode part 24 that is one end part in the long side direction and a power storage part 26 that is a remaining part of the anode part 24. Has been. Hereinafter, for convenience of explanation, the long side direction and the short side direction of the capacitor element 12 will be described as the X direction and the Y direction, respectively, and the direction orthogonal to the X direction and the Y direction will be described as the Z direction.

  As shown in FIG. 2, the anode part 24 is composed of an aluminum substrate 18 on which an aluminum oxide film 20 is formed. On the other hand, the power storage unit 26 has an outer peripheral surface of an aluminum substrate 18 on which an aluminum oxide film 20 functioning as a dielectric is formed, and a cathode unit 28 made of a solid polymer electrolyte layer 21, a graphite paste layer 22, and a silver paste layer 23. It has a covering structure. Note that an insulating resin layer 27 made of an epoxy resin or a silicone resin is formed in a belt-like region at the boundary between the anode part 24 and the power storage part 26.

  The capacitor element 12 having the above-described shape is formed by punching an aluminum foil having a roughened surface and subjected to a chemical conversion treatment. Therefore, an aluminum oxide film is formed on the end surface of the foil from which aluminum is exposed by immersing the formed aluminum foil in a chemical conversion solution. The chemical conversion liquid is preferably, for example, an aqueous solution of ammonium adipate having a concentration of 3%.

  Here, the process applied to the aluminum foil used as the capacitor | condenser element 12 is demonstrated, referring FIG. FIG. 3 is a diagram showing a state in which an anodizing process is performed on the aluminum foil 30 to be a capacitor element. First, the insulating resin layer 27 is formed in the band-like edge region on the side of the portion 26 </ b> A to be the power storage portion 26 in the surface region of the portion 24 </ b> A to be the anode portion 24 of the aluminum foil 30. Thus, by forming the insulating resin layer 27 in the predetermined region, the anode part 24 and the cathode part 28 formed in the subsequent stage can be reliably insulated and separated.

  Then, the aluminum foil 30 is immersed in a chemical conversion solution 36 made of an aqueous solution of ammonium adipate accommodated in a stainless beaker 34 with the aluminum foil supported by the portion 24 </ b> A to be the anode portion 24. A voltage is applied with the supported aluminum foil portion 24A being positive and the stainless beaker 34 being negative. The value of the applied voltage can be appropriately determined according to the film thickness of the aluminum oxide film 20 to be formed, and when forming the aluminum oxide film 20 having a film thickness of 10 nm to 1 μm, usually several volts to 20 It is about a bolt.

  When the anodic oxidation is started by voltage application, the chemical conversion solution 36 rises from the liquid level through the surface of the aluminum foil 30 whose surface is roughened by capillary action. Therefore, the aluminum oxide film 20 is formed on the entire surface of the aluminum foil 30 whose surface including the end face is roughened. By forming the cathode portion 28 on the aluminum foil 30 thus produced by a known method, the production of the capacitor element 12 described above is completed.

  Next, the substrate 14 on which the capacitor element 12 is mounted will be described with reference to FIG. Here, FIG. 4 is a plan view of the element mounting surface 14a of the substrate 14 as viewed from the element mounting surface 14a side.

  The substrate 14 is a printed circuit board made of FR4 material (epoxy resin material) in which a copper foil pattern having a predetermined shape is etched on the main surface 14a. On the element mounting surface 14a on which the capacitor element 12 of the substrate 14 is mounted, as shown in FIG. 4, two rectangular electrode patterns 38A and 38B are arranged in parallel along the X direction. These electrode patterns 38A and 38B are formed so as to be included in a rectangular element mounting region 15 in which the capacitor element 12 is mounted on the element mounting surface 14a. In the present embodiment, the element mounting area 15 substantially coincides with the entire area of the element mounting surface 14a.

  Here, the element mounting region 15 includes an anode portion region 15 a facing the anode portion 24 of the capacitor element 12 and a cathode portion region 15 b facing the cathode portion 28 on the surface of the power storage portion 26 of the capacitor element 12. Yes. The electrode pattern 38 </ b> A is formed in the anode portion region 15 a of the element mounting region 15. The electrode pattern 38 </ b> B is formed in the cathode portion region 15 b of the element mounting region 15.

  The anode portion 24 of the capacitor element 12 is connected to the narrower electrode pattern 38A of the pair of electrode patterns 38A and 38B by resistance welding or metal welding such as a YAG laser spot. On the other hand, the cathode portion 28 on the surface of the power storage unit 26 of the capacitor element 12 is connected to the electrode pattern 38B having a larger width by a conductive adhesive (not shown). Hereinafter, for convenience of explanation, the electrode pattern 38A connected to the anode portion 24 of the capacitor element 12 is referred to as an anode pattern, and the electrode pattern 38B connected to the cathode portion 28 of the capacitor element 12 is referred to as a cathode pattern.

  Further, on the back surface of the element mounting surface 14a of the substrate 14, an anode terminal (not shown) connected to the above-described anode pattern 38A and a cathode terminal (not shown) connected to the cathode pattern 38B are provided. ing. Each electrode pattern 38A, 38B is connected to each terminal through a via (not shown) penetrating along the thickness direction of the substrate 14. Such a via can be formed, for example, by filling a through hole formed by drilling in the substrate 14 with metal plating (for example, electroless copper plating).

  Note that an insulating resin layer (not shown) is formed on the element mounting surface 14a of the substrate 14 to cover predetermined regions of the electrode patterns 38A and 38B. This insulating resin layer separates and insulates the anode pattern 38A and the cathode pattern 38B, and a material such as an epoxy resin or a silicone resin is used.

  Further, on the element mounting surface 14 a of the substrate 14, a buffer film 60 is provided in the outer peripheral area 17 </ b> A (hatched area in FIG. 6) of the element mounting area 15. The buffer film 60 is made of, for example, an insulating resin, and is formed in an annular shape so as to surround the electrode patterns 38A and 38B formed in the element mounting region 15. Therefore, when the capacitor element 12 is installed in the element mounting region 15, the capacitor element 12 is completely surrounded by the buffer film 60.

  The substrate 14 is covered with a resin mold 16 with the capacitor element 12 mounted on the element mounting region 15. Hereinafter, an adhesion state between the resin mold 16 and the substrate 14 will be described with reference to FIG. Here, FIG. 5 is a cross-sectional view taken along line VV of the solid electrolytic capacitor 10 shown in FIG.

  As described above, the buffer film 60 is formed in the outer peripheral region 17 </ b> A of the element mounting region 15 in the region of the element mounting surface 14 a of the substrate 14. Therefore, as shown in FIG. 5, a buffer film 60 is interposed between the resin mold 16 and the substrate 14 in the outer peripheral region 17A.

  Since the buffer film 60 is made of an elastic material such as resin as described above, the buffer film 60 is deformed when stress is generated between the resin mold 16 and the substrate 14. Then, due to the deformation of the buffer film 60, the distortion caused by the stress between the resin mold 16 and the substrate 14 is significantly absorbed. That is, in the above-described solid electrolytic capacitor 10, distortion due to stress between the resin mold 16 and the substrate 14 is reduced by the buffer film 60. Thereby, the peeling between the resin mold 16 and the substrate 14 due to the stress is suppressed, and the adhesion between the substrate 14 and the resin mold 16 is enhanced.

  Here, when peeling occurs between the resin mold 16 and the substrate 14, the outside air containing moisture enters the solid electrolytic capacitor 10 from between the substrate 14 and the resin mold 16, and the moisture in the outside air becomes a capacitor element. 12 and the electrode patterns 38A and 38B are adversely affected. That is, when peeling occurs between the resin mold 16 and the substrate 14, the moisture resistance characteristics of the solid electrolytic capacitor are deteriorated, and the electrical characteristics are remarkably deteriorated.

  That is, in the solid electrolytic capacitor 10, peeling between the resin mold 16 and the substrate 14 is suppressed by the buffer film 60, and the moisture resistance characteristics are improved. As a result, deterioration of electrical characteristics is suppressed. ing. Therefore, even when the solid electrolytic capacitor 10 is left or used in a moisture-resistant environment, the deterioration of electrical characteristics is significantly suppressed.

Further, by selecting a material having a thermal expansion coefficient between the thermal expansion coefficient of the resin mold 16 and the thermal expansion coefficient of the substrate 14 as a constituent material of the buffer film 60, the resin mold 16 and the substrate 14 by thermal expansion The stress caused by the thermal expansion gap between the two is effectively suppressed. Therefore, the peeling between the resin mold 16 and the substrate 14 is more effectively suppressed, the adhesion force is further strengthened, and the deterioration of the electrical characteristics is more significantly suppressed.

  Note that the formation region of the buffer film 60 described above is not limited to the region described above, and may be, for example, a region as shown in FIG. That is, in the substrate 14 shown in FIG. 6, the buffer film 60 includes the band-like region 17 </ b> B extending in the Y direction between the electrode patterns 38 </ b> A and 38 </ b> B in the element mounting region 15 in addition to the outer peripheral region 17 </ b> A of the element mounting region 15. Is also provided. That is, the buffer film 60 is provided in the entire remaining area of the element mounting area 15 where the electrode pattern (that is, the anode pattern 38A and the cathode pattern 38B) is formed. As described above, by expanding the region where the buffer film 60 is formed as wide as possible, the adhesion between the substrate 14 and the resin mold 16 is further strengthened, and the moisture resistance characteristics of the solid electrolytic capacitor 10 are further improved. In addition, the deterioration of electrical characteristics is further suppressed.

Further, the resin constituting the buffer film 60 may contain a filler. As shown in FIG. 7, when the resin 61 constituting the buffer film 60 includes a filler 62 made of, for example, SiO ₂ or Al ₂ O ₃ , the buffer film 60 is formed when the buffer film 60 is formed on the substrate 14. The surface roughness of the film surface increases, and the surface of the buffer film 60 becomes a rough surface instead of a flat surface. When the resin mold 16 is formed on such a buffer film 60, the adhesion between the buffer film 60 and the resin mold 16 is improved due to the anchor effect and the enlargement of the adhesion area. As a result, the adhesion between the substrate 14 and the resin mold 16 is also strengthened, so that the moisture resistance characteristics of the solid electrolytic capacitor 10 are further improved and the deterioration of the electrical characteristics is further suppressed.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, the capacitor element may be of a multi-terminal type having a plurality of anode parts and cathode parts, for example.

  Hereinafter, in order to further clarify the effects of the present invention, examples will be described.

  An electrolytic capacitor similar to the solid electrolytic capacitor 10 shown in FIG. 1 was produced as follows.

First, an aluminum anode electrode body is shown in FIG. 3 from an aluminum foil sheet that has a thickness of 100 μm and is provided with an aluminum oxide film and has a capacitance of 270 μF / cm ² . The same shape as that of the aluminum foil 30, and the size of the portion excluding the portion corresponding to the anode portion (corresponding to reference numeral 24A in FIG. 3) is 4.7 mm × 3.5 mm (area: 0.165 cm ² ). It was produced by punching. Then, in the punched electrode body, the roughened structure in the region where the insulating resin layer is formed (the region corresponding to reference numeral 27 in FIG. 3) was destroyed by pressing. In the electrode body thus manufactured, an epoxy resin was applied to only the surface of the area subjected to the pressing process (area corresponding to reference numeral 27 in FIG. 3) and coated.

  Further, the electrode body obtained in this manner was 6.0% in a concentration of 3% by weight so that the aluminum foil on which the aluminum oxide film was formed and the surface roughening treatment was completely immersed. In an aqueous solution of ammonium adipate adjusted to the pH of the solution. At this time, the electrode body was immersed in an aqueous solution of ammonium adipate up to a part of the region coated with the epoxy resin.

Next, the electrode body immersed in the aqueous solution is formed with a formation current density of 50 to 100 mA / cm ^{2 using the} portion corresponding to the anode portion and not coated with epoxy resin (corresponding to reference numeral 24A in FIG. 3) as the anode. Then, oxidation was performed under the condition of a formation voltage of 12 V, and an aluminum oxide film was formed on the end face of the cut portion of the electrode body.

  Thereafter, the electrode body was pulled up from the aqueous solution, and a solid polymer electrolyte layer made of polypyrrole was formed by chemical oxidation polymerization on the surface of the aluminum foil subjected to the roughening treatment. More specifically, in the solid polymer electrolyte layer made of polypyrrole, only the aluminum foil portion (corresponding to reference numeral 26A in FIG. 3) in which the above-mentioned electrode body is roughened and an aluminum oxide film is formed. Set in an ethanol water mixed solution cell containing purified 0.1 mol / l pyrrole monomer, 0.1 mol / l sodium alkylnaphthalene sulfonate and 0.05 mol / l iron (III) sulfate. The chemical oxidative polymerization was allowed to proceed by stirring for 30 minutes, and the same operation was repeated three times. As a result, a solid polymer electrolyte layer having a maximum thickness of about 50 μm was formed.

  A carbon paste and a silver paste were sequentially applied to the surface of the solid polymer electrolyte layer thus laminated to form a cathode portion similar to the cathode portion 28 of the capacitor element 12 shown in FIG.

  Thirty solid electrolytic capacitors were prepared in which the capacitor elements produced as described above were laminated in six stages. A conductive adhesive was used to connect the cathode portions of the capacitor elements.

  In addition, the board | substrate used is an electrolytic capacitor mounting board (7.3 mm x 4.3 mm), and is a glass cloth containing heat resistant epoxy resin board | substrate (FR4 board | substrate). On the element mounting surface of this substrate, a copper foil electrode pattern and a resin buffer film as shown in FIG. 4 were formed by patterning using a known photolithography technique. The thickness of the substrate is 0.5 mm, the thickness of the copper foil pattern is 36 μm, and the thickness of the buffer film is 20 μm. The buffer film was formed using a resin that did not contain a filler.

  Further, a through hole (0.2 mm diameter) was formed at a predetermined via formation position on the substrate 14, and nickel plating of 3 μm was applied to the inner wall of the through hole by electroless plating. Further, 0.08 μm gold plating was applied on the nickel plating. Further, copper plating was performed so as to fill all the above-described through holes, and vias were formed.

  The capacitor element was mounted on the substrate surface using a silver-based conductive adhesive so that the cathode portion overlapped the cathode pattern on the substrate surface. Further, the anode part of the capacitor element was welded and joined to the anode pattern on the substrate surface with a NEC YAG laser spot welder.

As described above, 30 solid electrolytic capacitors (sample # 1) as shown in FIG. 1 were prepared. In addition, by the same manufacturing method as described above, a solid electrolytic capacitor (sample # 2) in which an Al ₂ O ₃ filler is contained in the resin constituting the buffer film and a solid electrolytic capacitor in which the SiO ₂ filler is contained in the resin constituting the buffer film Thirty samples (Sample # 3) were prepared.

  For comparison, 30 solid electrolytic capacitors (sample # 4) that differ from the solid electrolytic capacitor of sample # 1 only in that there is no buffer film were prepared.

  The moisture resistance characteristics of each of the solid electrolytic capacitors # 1 to # 4 were evaluated. As a method for evaluating the moisture resistance, the samples # 1 to # 4 are allowed to stand for 500 hours and 1000 hours in a high-temperature and high-humidity environment (60 ° C., 90% RH). The ratio was measured, and for each sample # 1 to # 4, 30 average values were calculated and compared. In general, it is considered that the electrical characteristic that changes most significantly when moisture enters the capacitor is a capacitance characteristic. This is because the dielectric constant of water is about 80, and the dielectric constant of the alumina oxide film is 13. Therefore, when moisture enters the capacitor, the dielectric constant of the oxide film (dielectric layer) of the capacitor element is apparently increased. It is thought that. In addition, each of the samples # 1 to # 4 was mounted on a predetermined evaluation substrate, and the capacitance was measured using an impedance analyzer 4194A and a network analyzer 8753D manufactured by Agilent Technologies.

  The evaluation results of the moisture resistance characteristics were as shown in Table 1 below.

  As shown in Table 1, the sample # 4 not provided with the buffer film has a significantly increased capacitance after 500 hours and after 1000 hours compared to the samples # 1 to # 3 provided with the buffer film. is doing. Specifically, after 500 hours, the rate of change in capacitance of samples # 1 to # 3 with time was about 1%, whereas the rate of change with time of sample # 4 was only 5%. It was as large as 7%. Further, after 1000 hours, the rate of change in capacitance of samples # 1 to # 3 with time was about 2 to 6%, whereas only the rate of change with time of capacitance of sample # 4 was 24. It was as large as 1%.

  From the above results, it can be seen that in Samples # 1 to # 3, an increase in capacitance under a high-temperature and high-humidity environment is suppressed, and from this, a decrease in moisture resistance is suppressed. From the comparison with Sample # 4, it is considered that such improvement in moisture resistance is due to the fact that the separation between the substrate and the mold is significantly suppressed by providing the buffer film. That is, each of the samples # 1 to # 3 has improved moisture resistance characteristics and suppressed deterioration of electrical characteristics (that is, increase in capacitance). Further, from the results of Table 1, in samples # 2 and # 3 in which fillers are added to the resin constituting the buffer film, further improvement of moisture resistance characteristics is achieved, and deterioration of electrical characteristics is more effectively suppressed. You can see that

  Furthermore, the inventors evaluated the adhesion strength between the substrate and the mold using the samples # 1 to # 4 described above. As a method for evaluating the adhesion strength, samples # 1 to # 4 are left for 500 hours and 1000 hours in an environment of thermal shock (repeating −55 ° C. and 125 ° C. every 30 minutes), and at that time Tensile strength and the rate of change over time were measured, and for each sample # 1 to # 4, 30 average values were calculated and compared. The tensile strength was measured by pulling each sample # 1 to # 4 in the thickness direction by a pair of load cells 70A and 70B as shown in FIG. In FIG. 8, reference numeral 72 indicates a substrate corresponding to the above-described substrate 14, reference numeral 74 indicates a buffer film corresponding to the above-described buffer film 60, and reference numeral 76 indicates a mold corresponding to the above-described resin mold 16.

  The evaluation results of the adhesion strength were as shown in Table 2 below.

  As shown in Table 2, the tensile strength after 500 hours and after 1000 hours is remarkably lowered in Sample # 4 without the buffer film compared to Samples # 1 to # 3 with the buffer film. ing. Specifically, after the elapse of 500 hours, the temporal change rate of the tensile strength of the samples # 1 to # 3 was −10% or less, whereas only the temporal change rate of the tensile strength of the sample # 4 was −11. % Exceeded. Further, after 1000 hours, the rate of change with time in the tensile strength of Samples # 1 to # 3 was about −6 to −16%, whereas only the rate of change with time of the tensile strength of Sample # 4 was −36. It was as large as 5%.

  From the above results, in samples # 1 to # 3, the decrease in tensile strength under the environment of thermal shock is suppressed, and from this, it is understood that the decrease in adhesion strength is suppressed even under such circumstances. It was. From the comparison with Sample # 4, such an improvement in adhesion strength is considered to be due to the improvement in adhesion between the substrate and the mold by providing the buffer film. Further, from the results in Table 2, it can be seen that the adhesion strength is further improved in Samples # 2 and # 3 in which fillers are added to the resin constituting the buffer film.

1 is a perspective view showing a solid electrolytic capacitor according to an embodiment of the present invention. It is a schematic cross section which shows the principal part of the solid electrolytic capacitor shown in FIG. It is a figure which shows the state which has performed the anodizing process to the aluminum foil used as a capacitor | condenser element. It is the top view which showed the element mounting surface of the board | substrate. It is the VV sectional view taken on the line of the solid electrolytic capacitor shown in FIG. It is the figure which showed the buffer film of the aspect different from the buffer film shown in FIG. It is the principal part enlarged view which showed a mode that the filler was contained in the buffer film. It is the figure shown about the tensile strength test in an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Solid electrolytic capacitor, 12 ... Capacitor element, 14 ... Board | substrate, 14a ... Element mounting surface, 15 ... Element mounting area, 16 ... Resin mold, 17A ... Outer periphery area | region, 17B ... Strip | belt-shaped area | region, 24 ... Anode part, 28 ... Cathode Part, 38A ... anode pattern, 38B ... cathode pattern, 60 ... buffer film, 61 ... resin, 62 ... filler.

Claims (5)

A capacitor element having an anode part and a cathode part;
A substrate on which an anode pattern connected to the anode part and a cathode pattern connected to the cathode part are formed in an element mounting area of an element mounting surface on which the capacitor element is mounted;
A resin mold that integrally covers the substrate with the capacitor element;
A solid electrolytic capacitor, wherein the substrate is provided with a buffer film in an outer peripheral region of the element mounting region, and the buffer film is interposed between the resin mold and the substrate.   The solid electrolytic capacitor according to claim 1, wherein the buffer film has a thermal expansion coefficient between a thermal expansion coefficient of the substrate and a thermal expansion coefficient of the resin mold.   3. The solid electrolytic capacitor according to claim 1, wherein the buffer film is provided in an entire remaining area of the element mounting area where the anode pattern and the cathode pattern are formed.   The solid electrolytic capacitor according to claim 1, wherein the buffer film is made of a resin.   The solid electrolytic capacitor according to claim 4, wherein the resin constituting the buffer film contains a filler.

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