JP2010129826A - Electronic apparatus and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the penetration of a solvent of a bonding assisting agent into a conductive bonding agent in an electronic apparatus in which a substrate and an electronic component connected via the conductive bonding agent are sealed with a molding resin via the bonding assisting agent. <P>SOLUTION: The electronic apparatus includes an electronic component 20 mounted to one surface of the substrate 10, a conductive bonding agent 30 provided between the electronic component 20 and the one surface of the substrate 10, a molding resin 40 for sealing one surface of the substrate 10, the electronic component 20 and the conductive bonding agent 30, and a bonding assisting agent 50 provided between the one surface of substrate 10 and the molding resin 40 for securing the bonding property of the molding resin 40. In the electronic apparatus, a protecting material 60 is provided on the surface in contact with the molding resin 40 in the conductive bonding agent 30 to cover and protect the relevant surface. Moreover, the relevant surface is in contact with the molding resin 40 via the protecting material 60, and the protecting material 60 and a solvent in the bonding assisting agent 50 are formed of materials whose differences of solubility parameters are three or larger. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electronic device in which a substrate and an electronic component connected via a conductive adhesive are sealed with a mold resin, and a method for manufacturing such an electronic device, in particular, a mold resin and a substrate. In order to ensure adhesiveness to the substrate, the present invention relates to an adhesion aid applied to the substrate before resin sealing.

  Conventionally, as an electronic device of this type, a conductive adhesive comprising a conductive filler on an epoxy resin is applied on one surface of a substrate, and an electronic component is mounted on the conductive adhesive. After the conductive adhesive is cured to electrically connect the electronic component and the substrate, the adhesive auxiliary agent is applied to one surface of the substrate and cured, and then the substrate on which the adhesive auxiliary agent is formed is cured. On the other hand, what sealed an electronic component and a conductive adhesive with mold resin is proposed (for example, refer to patent documents 1).

In such an electronic device, the mold resin is made of an epoxy resin, the adhesion aid is made by dissolving a resin such as polyamide in a solvent, and the adhesion aid is placed between one surface of the substrate and the mold resin. It interposes and secures the adhesiveness of the mold resin.
JP 7-278301 A

  By the way, according to the study of the present inventor, when the adhesion assistant is applied to one surface of the substrate on which the electronic component is mounted via the conductive adhesive, the solvent in the adhesion assistant becomes the conductive adhesive. It has been found that the conductive adhesive swells when permeated and causes an increase in electrical connection resistance in the conductive adhesive.

  In this case, it may be simply configured such that the adhesion auxiliary agent is eliminated. However, if this is done, the adhesion between the substrate and the mold resin is lowered, the mold resin is peeled off, and further, the wire is formed on one surface of the substrate. When bonding is performed, problems such as disconnection of the wire due to peeling of the mold resin are expected.

  The present invention has been made in view of the above problems, and in an electronic device in which a substrate and an electronic component are connected via a conductive adhesive and sealed with a mold resin via an adhesive auxiliary agent. The object is to prevent the solvent in the adhesion aid from penetrating into the conductive adhesive.

  In order to achieve the above object, in the first aspect of the present invention, the surface of the conductive adhesive (30) that contacts the mold resin (40) is covered with a protective material (60) that protects the surface. The surface is in contact with the mold resin (40) via the protective material (60), and the difference in solubility parameter between the protective material (60) and the solvent in the adhesion aid (50) is 3 or more. It is characterized by being made of material.

  The present invention has been found experimentally, and the surface of the conductive adhesive (30) that is in contact with the mold resin (40) has a solubility parameter difference of 3 from the solvent in the adhesive aid (50). If the protective material (60) made of the above material is covered and protected, the protective film (60) repels the adhesion assistant (50), so that the solvent in the adhesion assistant (50) is a conductive adhesive (30). ) Can be prevented.

  Here, as in the invention described in claim 2, the mold resin (40) is an epoxy resin, and the conductive adhesive (30) comprises a conductive filler in the epoxy resin, and is an adhesion assistant. The agent (50) can be prepared by diluting polyamide with N-methylpyrrolidone as a solvent.

  The invention according to claim 3 applies a conductive adhesive (30) to one surface of the substrate (10), and mounts an electronic component (20) on the conductive adhesive (30). The conductive adhesive (30) is cured to electrically connect the electronic component (20) and the substrate (10). Next, the adhesive property of the mold resin (40) is secured on one surface of the substrate (10). The adhesive auxiliary agent (50) to be formed is formed by coating and curing, and then the one surface of the substrate (10) on which the adhesive auxiliary agent (50) is formed, the electronic component (20), and the conductive adhesive (30) are molded. In the manufacturing method of the electronic device sealed with resin (40), it has the following characteristics.

  That is, the protective material (60) made of a material having a solubility parameter difference of 3 or more with respect to the solvent in the adhesion assistant (50) on the surface of the cured conductive adhesive (30) in contact with the mold resin (40). By coating and curing, the surface is covered with a protective material (60), and then the adhesion auxiliary agent (50) is applied.

  The present invention has been found experimentally, and the surface of the conductive adhesive (30) that is in contact with the mold resin (40) has a solubility parameter difference of 3 from the solvent in the adhesive aid (50). If it protects by covering with the protective material (60) which consists of the above material, even if it apply | coats an adhesion adjuvant (50) after that, since a protective film (60) will play an adhesion adjuvant (50), adhesion assistance It is possible to prevent the solvent in the agent (50) from penetrating into the conductive adhesive (30).

  And also in this manufacturing method, like invention of Claim 4, a mold resin (40) is an epoxy resin, and a conductive adhesive (30) contains a conductive filler in an epoxy resin. The adhesion assistant (50) can be obtained by diluting polyamide with N-methylpyrrolidone as a solvent.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, parts that are the same or equivalent to each other are given the same reference numerals in the drawings for the sake of simplicity.

  FIG. 1 is a diagram showing a schematic cross-sectional configuration of an electronic device according to an embodiment of the present invention. The electronic device according to the present embodiment is used for, for example, an ECU of an automobile. In general, the substrate 10, the electronic component 20 mounted on one surface of the substrate 10, and the electronic component 20 and the substrate 10 are electrically connected. The conductive adhesive 30 connected to the substrate 10, the mold resin 40 that seals the members 10 to 30, and the adhesion assistant 50 that ensures the adhesion between the substrate 10 and the mold resin 40 are provided.

  Although it does not specifically limit as the board | substrate 10, Various circuit boards, such as a ceramic board | substrate and a printed circuit board, and a wiring board are mentioned. Further, the substrate 10 may be a lead frame or the like.

  The electronic component 20 may be anything as long as it is surface-mounted by the conductive adhesive 30 on one surface (the upper surface in FIG. 1) of the substrate 10. For example, as the electronic component 20, an IC chip, a diode, Examples include capacitors and resistors.

  The conductive adhesive 30 is a general epoxy-based conductive adhesive, specifically, a composition comprising an epoxy resin and a conductive filler such as Ag or Cu contained and dispersed in the epoxy resin. is there.

  The mold resin 40 is made of this kind of general epoxy resin such as a naphthalene type epoxy resin, and is molded by a dispensing method, a transfer molding method, or the like.

  Further, the adhesion assistant 50 is used as a primer for the mold resin 40, and is provided here between one surface of the substrate 10 and between the electronic component 20 and the mold resin 40. The function of the adhesion assistant 50 is to improve the adhesion between one surface of the substrate 10 and the electronic component 20 and the mold resin 40, and to relieve internal stress.

  For example, as the adhesion assistant 50, a general material obtained by diluting a resin such as polyetheramide imide (PAI), polyamide (PA), polyimide (PI) with a solvent such as NMP (N-methylpyrrolidone) or acetone. It is formed using. And this adhesion adjuvant 50 is arrange | positioned by apply | coating a liquid thing by potting, printing, etc., and hardening this.

  As shown in FIG. 1, the adhesion assistant 50 is not interposed between the surface of the conductive adhesive 30 that contacts the mold resin 40 and the mold resin 40. The surface of the conductive adhesive 30 that is in contact with the mold resin 40 is the surface of the conductive adhesive 30 that protrudes from the outer peripheral edge of the electronic component 20, and conventionally, an adhesion assistant is applied to this surface. .

  However, in the present embodiment, the adhesive auxiliary agent 50 does not exist on the surface of the conductive adhesive 30 that protrudes from the outer peripheral end portion of the electronic component 20, and instead the protection that covers and protects the surface. A material 60 is provided. The surface of the conductive adhesive 30 is in contact with the mold resin 40 through the protective material 60.

In the present embodiment, the difference in solubility parameter between the material forming the protective material 60 and the solvent in the adhesion aid 50 is 3 or more. Here, according to Iwanami Shoten, RIKEN Dictionary 5th edition (page 1406), “the solubility parameter is δ = (ΔH / V) ^{1 /, where} ΔH is the molar evaporation heat of the liquid and V is the molar volume. refers to the amount δ defined by ^2. Hildebrand (Hildebrand, J. H.) in amounts that appear in the theory of regular solution, such activity of each component of a two component system, a two-component solubility parameter It depends directly on the difference, and the solubility increases as the difference between the solubility parameters of the two decreases. "

  This solubility parameter (Solubility Parameter, hereinafter referred to as SP value) is an intrinsic property value, and it is known from experience that a substance having a close SP value tends to be mixed.

  In the present embodiment, the SP value of the material forming the protective material 60 has a difference of 3 or more with respect to the SP value of the solvent in the adhesion aid 50. Here, the difference in SP value is an absolute value, and if the difference in SP value is 3 or more, the SP value of the protective material 60 is smaller or larger than the SP value of the solvent in the adhesion aid 50. Also good.

  Specifically, the SP value of the material forming the mold resin 40, for example, the SP value of naphthalene type epoxy resin is 11.6, the SP value of the material forming the conductive adhesive 30, for example, an epoxy resin containing a conductive filler The SP value is 11.2, and the SP value of N-methylpyrrolidone which is a solvent in the adhesion assistant 50 is 11.0.

  Specifically, as a material for forming the protective material 60 in which the difference in SP value is 3 or more with respect to the solvent in the adhesion aid 50, for example, a fluororesin (SP value: 3.6) is used. ) And silicone rubber (SP value: 8.0).

  Moreover, about the solvent in the adhesion adjuvant 50, and the mold resin 40, the thing with a mutually small SP value difference is used, the adhesiveness of the board | substrate 10 and the mold resin 40 is maintained, and the mold resin 40 is peeled. It is difficult.

  In such an electronic device, the conductive adhesive 30 is applied to one surface of the substrate 10, the electronic component 20 is mounted thereon, and then the conductive adhesive 30 is cured to electrically connect the electronic component 20 and the substrate 10. After the connection, the protective material 60 is applied and cured on the surface of the conductive adhesive 30, and then the adhesive auxiliary agent 50 is applied and cured on one surface of the substrate 10 and the electronic component 20. Then, it manufactures by sealing with the mold resin 40. FIG.

  That is, in the manufacturing method of the present embodiment, after the conductive adhesive 30 is cured, the SP value difference between the cured conductive adhesive 30 and the solvent in the adhesion aid 50 on the surface in contact with the mold resin 40. Is formed by applying and curing a protective material 60 made of three or more materials, so that the surface of the conductive adhesive 30 is covered with the protective material 60, and thereafter, the adhesion auxiliary agent 50 is applied. It cures.

  As described above, in this embodiment, the surface of the conductive adhesive 30 that contacts the mold resin 40 is covered with the protective material 60 made of a material having a SP value difference of 3 or more from the solvent in the adhesion aid 50. After that, even if the adhesion assistant 50 is applied, the protective film 60 repels the adhesion assistant 50 and prevents the solvent of the adhesion assistant 50 from penetrating into the conductive adhesive 30. can do.

  This is because the protective material 60 and the adhesion assistant 50 are substantially mixed if the difference in SP value between the material forming the protection material 60 and the solvent in the adhesion assistant 50 is increased to 3 or more. This is because there will be nothing. This is based on an experiment conducted by the present inventor, and this examination will be described next.

  FIG. 2 is a schematic cross-sectional view showing a sample used in the experimental study conducted by the present inventor, and shows a state of the first connection resistance value measurement. Here, the ceramic substrate 10 was used as the substrate 10.

  The ceramic substrate 10 has a size of 1 inch □, a thickness of 1 mm, a material of alumina, and an Au plating 11 is applied to one surface on which the electronic component 20 is mounted. The electronic component 20 is a multilayer ceramic capacitor, the size is 3.2 × 1.6 × 1.25 mm, and the electrode material is Ag / Pd.

  An epoxy resin (SP value: 11.2) containing a conductive filler is used as the conductive adhesive 30, and a naphthalene type epoxy resin (SP value: 11.6) is used as the mold resin 40. As 50, polyamide diluted with N-methylpyrrolidone (SP value: 11.0) was used.

  Moreover, as a material which forms the protective material 60, fluororesin (SP value: 3.6), silicone rubber (SP value: 8.0), polystyrene (SP value: 9.0), vinylidene chloride resin (SP value) : 12.2) and epoxy resin (SP value: 11.0), samples were prepared and examined for these various materials.

  <Adhesive curing>: A conductive adhesive 30 is printed on the substrate 10 using a metal mask (not shown) having a printed pattern opened, and the electronic component 20 is mounted with no load, and then the conductive adhesive in a thermostatic chamber. 30 was cured. The printed film thickness of the conductive adhesive 30 was 60 μm, and the curing condition was 150 ° C. × 30 minutes. Thus, the ceramic substrate 10 and the electronic component 20 are connected by the conductive adhesive 30, and this state is shown in FIG.

  <First Connection Resistance Measurement>: The first connection resistance measurement was performed after the conductive adhesive 30 was cured and before the protective material 60 was applied. This connection resistance value is an electrical connection resistance value between the electronic component 20 and the substrate 10 via the conductive adhesive 30.

  As shown in FIG. 2, the connection resistance value was measured by a four-terminal method using a constant current source K1 and a digital multimeter K2. The current was 10 mA, the voltage was measured, and the resistance value was determined from the relationship of R = V / I. With this method, the first connection resistance value was measured for the manufactured sample.

  <Protective Material Application>: Next, a protective material 60 was formed on the surface of the cured conductive adhesive 30 in contact with the mold resin 40 by applying and curing the sample shown in FIG. 2 by a dispensing method. . As a result, as shown in FIG. 1, the surface of the conductive adhesive 30 was covered with the protective material 60.

  <Adhesion auxiliary agent application>: Next, the adhesion auxiliary agent 50 was applied to one surface of the substrate 10 and the surface of the electronic component 20 using the dispensing method, and was cured by heating.

  <Second measurement of connection resistance>: Thereafter, a probe was applied to the gold plating 11 of the substrate 10 where the adhesion assistant 50 was not attached, and the second connection resistance value was measured by the same four-terminal method as described above.

  <Mold resin sealing>: Thereafter, the mold resin 40 was applied onto one surface of the substrate 10 by a dispensing method, and the one surface of the substrate 10 and the electronic component 20 were sealed with the mold resin 40, and the mold resin 40 was cured. . Thus, an electronic device having the same shape as that shown in FIG. 1 was produced as a sample.

  FIG. 3 is a diagram showing the results of investigating the first and second connection resistance values for each sample of the comparative example and this embodiment. Here, the sample of the comparative example corresponds to a conventional structure, and is produced by the present inventor through a process in which the coating of the protective material is omitted in the manufacturing process of the sample for the above-described experimental study.

  Further, the sample of this embodiment in FIG. 3 has a structure using silicone rubber as the protective material 60, and in this case, the difference in SP value from the solvent in the adhesion aid 50 is 3. FIG. 3 shows values measured at n number: 10 for each sample of these comparative examples and embodiments.

  As shown in FIG. 3, there was no difference in the first connection resistance value between the comparative example and this embodiment. However, the second connection resistance value increased by about 15 times on average from the first connection resistance value in the sample of the comparative example having no protective material. On the other hand, the connection resistance value of the sample of this embodiment was not substantially changed between the first time and the second time.

  FIG. 4 shows a second connection in the case where a sample in which the type of the protective material 60 is changed and the difference in SP value between the protective material 60 and the solvent in the adhesion aid 50 is varied in the above experimental study. It is a figure which shows the result of resistance value. FIG. 4 shows the values measured with n number: 10 for each sample in which the difference in SP value is changed.

  In FIG. 4, the first connection resistance value of each sample is the first connection resistance value shown in FIG. 3, and the sample in which the second connection resistance value shown in FIG. This is an inappropriate one that does not exhibit the effects of the embodiment. As shown in FIG. 4, when the difference between the SP values was 3 or more, no increase in the resistance value was observed compared to the first connection resistance value.

  Specifically, among the specific protective materials 60 listed in the above experimental study, the fluorine resin (SP value: 3.6) and the silicone rubber (SP value: 8.0) have an SP value of 11. The difference of the SP value is 3 or more with respect to the solvent (NMP) in the adhesion assistant 50 which is 0, and the effect by this is also confirmed from FIG. However, in this embodiment, polystyrene (SP value: 9.0), vinylidene chloride resin (SP value: 12.2), and epoxy resin (SP value: 11.0) are inappropriate as the protective material 60. Is apparent from FIG.

  In consideration of this phenomenon, in the comparative example shown in FIG. 3, since there is no protective material, 50 NMP having an SP value close to that of the epoxy conductive adhesive 30 penetrates into the conductive adhesive 30. It is thought that the resistance increased.

  On the other hand, in the electronic device of this embodiment, when the difference in SP value between the protective material 60 and the solvent in the adhesion assistant 50 is 3 or more, the both play between the adhesion assistant 50 and the protection material 60. The conductive adhesive 30 was not attached to the conductive adhesive 30 and the solvent did not penetrate into the adhesive auxiliary 50, so that the conductive adhesive 30 did not swell and the increase in resistance was suppressed.

  Thus, based on the results of the experimental study conducted by the inventor, in this embodiment, the difference in SP value between the material forming the protective material 60 and the solvent in the adhesion aid 50 is set to 3 or more. -ing

(Other embodiments)
FIG. 5 is a diagram illustrating a schematic cross-sectional configuration of an electronic device according to another embodiment. In the above embodiment, the protective material 60 is provided on the surface of the conductive adhesive 30 in contact with the mold resin 40 and is not provided on the surface of the electronic component 20 in contact with the mold resin 40. As shown in FIG. 4, the protective material 60 may be further applied and cured so as to cover the surface of the electronic component 20.

  In this case, the adhesiveness between the electronic component 20 and the mold resin 40 is reduced as compared with the case where the adhesion assistant 50 is present on the surface of the electronic component 20, but the mold resin such as an electronic component that requires wire bonding is used. When the adhesive strength with 40 is not required, the peeled portion is rather less susceptible to the thermal stress of the surrounding environment on the connecting portion, and the life is improved. When the adhesion assistant 50 is not applied to the surface of the electronic component 20, the adhesion of the component itself to the mold resin 40 is increased, and a more stable structure can be obtained.

It is a schematic sectional drawing of the electronic device which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the sample used for the experiment examination which this inventor performed. It is a figure which shows the result of having investigated the connection resistance value about the comparative example and this embodiment. It is a figure which shows the result of having investigated the relationship between the difference of SP value of a protective material and the solvent in an adhesion adjuvant, and connection resistance value. It is a schematic sectional drawing of the electronic device which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Board | substrate 20 Electronic component 30 Conductive adhesive 40 Mold resin 50 Adhesion adjuvant 60 Protective material

Claims (4)

A substrate (10);
An electronic component (20) mounted on one surface of the substrate (10);
A conductive adhesive (30) interposed between the electronic component (20) and one surface of the substrate (10) to electrically connect these members (10, 20);
A mold resin (40) for sealing one surface of the substrate (10), the electronic component (20) and the conductive adhesive (30);
In an electronic device comprising an adhesion aid (50) interposed between one surface of the substrate (10) and the mold resin (40) and ensuring adhesion of the mold resin (40),
A protective material (60) that covers and protects the surface of the conductive adhesive (30) in contact with the mold resin (40) is provided, and the surface is provided via the protective material (60). In contact with the mold resin (40)
The electronic device according to claim 1, wherein the protective material (60) and the solvent in the adhesion aid (50) are made of a material having a solubility parameter difference of 3 or more.   The mold resin (40) is an epoxy resin, the conductive adhesive (30) comprises a conductive filler in an epoxy resin, and the adhesion auxiliary agent (50) uses polyamide as the solvent. The electronic device according to claim 1, wherein the electronic device is diluted with N-methylpyrrolidone. A conductive adhesive (30) is applied to one surface of the substrate (10), and an electronic component (20) is mounted on the conductive adhesive (30).
Next, the conductive adhesive (30) is cured to electrically connect the electronic component (20) and the substrate (10),
Next, on one surface of the substrate (10), an adhesion auxiliary agent (50) for ensuring the adhesion of the mold resin (40) is formed by application and curing,
Subsequently, one surface of the substrate (10) on which the adhesion assistant (50) is formed, the electronic component (20), and the conductive adhesive (30) are sealed with a mold resin (40). In the manufacturing method,
A protective material (60) made of a material having a solubility parameter difference of 3 or more with respect to the solvent in the adhesion assistant (50) on the surface of the cured conductive adhesive (30) in contact with the mold resin (40). ) Is applied and cured to coat the surface with the protective material (60), and then the adhesion assistant (50) is applied.   The mold resin (40) is an epoxy resin, the conductive adhesive (30) comprises a conductive filler in an epoxy resin, and the adhesion auxiliary agent (50) uses polyamide as the solvent. The method for manufacturing an electronic device according to claim 3, wherein the method is diluted with N-methylpyrrolidone.

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