JP2006216735A - Electronic component mounting substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic component mounting substrate which ensures higher fixing intensity of an electronic component to an insulating substrate. <P>SOLUTION: An electronic component 30 is connected to conductive patterns 11A, 11B via conductive bonding agent layers 20A, 20B by providing an interval L2 between a side end surface 31A1 of an electrode 31A and an end of a connector 11A1 of a conductive pattern 11A, and also providing an interval L3 between a side surface 31B1 of an electrode 31B and end of a connector 11B1 of a conductive pattern 11B. Accordingly, when a peeling force is applied to the electronic component 30, the peeling force is not transferred directly to the conductive patterns 11A, 11B, and the conductive patterns 11A, 11B are not easily peeled. The electronic component 30 is rigidly fixed to the surface of the insulating substrate 10 with conductive bonding agent layers 20A, 20B. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic component mounting substrate in which an electronic component is connected to a conductive pattern formed on an insulating substrate, and more particularly to an electronic component mounting substrate that can improve the fixing strength of the electronic component to the insulating substrate.

Patent Document 1 below discloses a method for attaching a chip-type electronic component to a substrate.
FIG. 3A is a plan view showing a conventional method for attaching a chip-type electronic component to a substrate, and FIG. 3B is a cross-sectional view taken along line 3-3 in FIG. 3A.

  In the flexible substrate 100, circuit patterns 102 and 102 are formed by screen-printing silver paste or the like on a flexible synthetic resin film (for example, polyethylene terephthalate film) 101, and the ends of the circuit patterns 102 and 102 are formed. Terminal patterns 103, 103 are formed in the part.

  An anisotropic hot-melt type conductive adhesive 104 is screen-printed on the terminal patterns 103 and 103 so as to cover the terminal patterns 103 and 103. In the conductive adhesive 104, metal powder (for example, copper powder, silver powder) and a solvent are mixed in a polyester-based thermoplastic resin (other resin may be used as long as it is a thermoplastic resin).

  The chip-type light emitting device 200 is provided with electrode terminals 201 and 201 so as to be directly exposed from the both side surfaces (the side surface on the X1 side in the drawing and the side surface on the X2 side in the drawing) to the bottom surface (the surface on the Z2 side in the drawing). It has been.

Then, the electrode terminals 201 and 201 of the chip type light emitting element 200 are respectively placed on the conductive adhesive 104 immediately above the terminal patterns 103 and 103, and the chip type light emitting element 200 is placed on the flexible substrate 100. The
JP-A-8-330712

  However, in the invention described in Patent Document 1, the circuit patterns 102 and 102 are provided at positions corresponding to the electrode terminals 201 and 201 under the conductive adhesive 104 on which the electrode terminals 201 and 201 are placed and bonded. Intervene. The circuit patterns 102 and 102 contain a large amount of silver in the paste in order to increase conductivity, and the mechanical strength of the circuit patterns 102 and 102 is weak. For this reason, when a peeling force (a force acting in the Z1 direction in the figure) is applied to the chip-type light emitting element 200 due to an external impact or the like, the peeling force is directly transmitted to the circuit patterns 102, 102, and the circuit patterns 102, 102 Is peeled off from the synthetic resin film 101. That is, there is a problem that the fixing strength of the chip type light emitting element 200 is low and the chip type light emitting element 200 is peeled off from the synthetic resin film 101 due to an external impact or the like.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide an electronic component mounting substrate having a high strength for fixing an electronic component to an insulating substrate.

The present invention provides an electronic component mounting substrate in which a conductive pattern having conductive metal powder and a binder resin is formed on a surface of an insulating substrate, and an electronic component mounted on the insulating substrate is electrically connected to the conductive pattern.
On the surface of the insulating substrate, a conductive adhesive layer having a conductive filler and a binder resin and having a density of the conductive filler lower than that of the conductive pattern is provided. The conductive adhesive layer is formed on the insulating substrate. Is formed without interposing the conductive pattern on the surface and is electrically connected to the conductive pattern,
The electronic component is installed on the conductive adhesive layer, and the electronic component and the insulating substrate are fixed via the conductive adhesive layer.

  In the said invention, an electronic component is adhere | attached on the surface of an insulated substrate through the conductive adhesive layer with low mixing density of a conductive filler, and has conductive metal powder between a conductive adhesive layer and an insulated substrate. Since the conductive pattern is not interposed, the fixing strength of the electronic component to the insulating substrate can be improved. Further, although the specific resistance of the conductive adhesive layer is higher than that of the conductive pattern, it is possible to suppress an increase in DC resistance of an electronic circuit including an electronic component because the conductive path of the conductive adhesive layer is extremely short.

  For example, in the present invention, a pair of conductive patterns are provided on the insulating substrate so as to face each other, and a pair of conductive adhesive layers are spaced between the ends of the pair of conductive patterns. It is possible to configure such that each of both end portions of the electronic component is installed on the conductive adhesive layer.

  In the above structure, it is preferable that an insulating protrusion protruding from the insulating substrate is provided between the two conductive adhesive layers.

  Since the conductive adhesive layer has a low mixing density of the conductive filler, there is a possibility that in the molten state, the conductive adhesive layer may proceed by a capillary action in the gap between the surface of the insulating substrate and the bottom surface of the electronic component. By providing, it can prevent that the conductive adhesive layer which fixes the both ends of an electronic component contacts, and a short circuit arises.

  In the electronic component mounting substrate of the present invention, the electronic component and the insulating substrate are fixed via the conductive adhesive without interposing the conductive pattern. Therefore, even when a peeling force acts on the electronic component, this The peeling force is received by the conductive adhesive having a strong adhesive force, and the peeling force is less likely to act directly on the conductive pattern. Therefore, it can suppress that a conductive pattern peels from the surface of an insulating substrate.

  As a result, the fixing strength of the electronic component can be increased, and the possibility that the electronic component is separated from the surface of the insulating substrate due to an external impact or the like can be reduced.

  FIG. 1 is a partial plan view showing an electronic component mounting board according to the present invention, and FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. In FIG. 1, the resist layer covering the conductive pattern is not shown in order to clarify the shape of the conductive pattern.

  Reference numeral 10 denotes a flexible insulating substrate formed of a polyester resin such as polyethylene terephthalate, a polyimide resin, or the like. As shown in FIG. 1, a pair of conductive patterns 11A and 11B are formed on the surface of the insulating substrate 10 (the surface on the Z1 side in the drawing) so as to face each other with a predetermined interval L0 in the X1-X2 direction in the drawing. ing. Although only one pair of conductive patterns 11A and 11B is shown in FIG. 1, a plurality of pairs of conductive patterns are actually formed on the insulating substrate 10.

  In the conductive pattern 11A, the connection portion 11A1 and the wiring portion 11A2 are integrally formed, and in the conductive pattern 11B, the connection portion 11B1 and the wiring portion 11B2 are integrally formed. The connecting portions 11A1 and 11B1 are formed larger in width (dimension in the Y1-Y2 direction in the drawing) than the wiring portions 11A2 and 11B2, and function as so-called land portions having a predetermined area.

  The conductive patterns 11A and 11B are formed on the insulating substrate 10 with a conductive material containing conductive metal powder such as Ag. The conductive material is screen-printed with a conductive paste or conductive ink containing the conductive metal powder and an organic solvent on a binder resin made of a thermosetting resin such as a phenol resin, whereby a predetermined amount is applied to the insulating substrate 10. Printed with a pattern. The organic solvent is removed by baking after screen printing. As a result, the conductive coating mainly composed of the conductive metal powder and the binder resin adheres to the surface of the insulating substrate 10 as the conductive patterns 11A and 11B. To be formed.

  As shown in FIG. 2, resist layers 12 and 12 are formed on the wiring portions 11A2 and 11B2 of the conductive patterns 11A and 11B, and the wiring portions 11A2 and 11B2 are completely covered with the resist layer 12. The resist layer 12 is cured through a predetermined heating process after being applied to the wiring portions 11A2 and 11B2.

  On the insulating substrate 10, a position corresponding to a position where the electronic component 30 such as a chip resistor is placed between the conductive patterns 11 </ b> A and 11 </ b> B, for example, a connection portion of the conductive pattern 11 </ b> A as shown in FIG. 2. Insulation formed from an insulating material at a position where the distance from the tip of 11A1 and the distance from the tip of the connecting portion 11B1 of the conductive pattern 11B is L0 / 2 (the midpoint position between the conductive pattern 11A and the conductive pattern 11B). A protrusion 13 is provided.

  The electronic component 30 is provided with an electrode 31A on the side end surface 30a on the X1 side in the drawing and an electrode 31B on the end surface 30b on the X2 side in the drawing, and is a chip used as a resistor, a capacitor, a coil, or the like. It is a part. Alternatively, the electronic component 30 may be an electronic component such as an IC having three or more electrodes or a composite electronic component.

Next, a method for connecting the electronic component 30 to the conductive patterns 11A and 11B will be described.
First, as shown in FIG. 2, a conductive adhesive layer 20A is applied on the insulating substrate 10 between the connecting portion 11A1 of the conductive pattern 11A and the insulating protrusion 13 and on the tip of the connecting portion 11A1. The adhesive layer 20B is applied on the insulating substrate 10 between the connecting portion 11B1 of the conductive pattern 11B and the insulating protrusion 13 and on the tip of the connecting portion 11B1. That is, in the region where the electronic component 30 is placed on the insulating substrate 10, only the conductive adhesive layer exists between the insulating substrate 10 and the electronic component 30 in at least a part of the region, and the conductive bonding is performed. Conductive patterns 11A and 11B do not exist between the agent layer and the insulating substrate 10.

  In the conductive adhesive layers 20A and 20B, a conductive filler such as Ag or carbon is mixed in a thermosetting binder resin such as epoxy or phenol. The conductive adhesive layers 20A and 20B are in the form of a paste containing an organic solvent. The conductive adhesive layers 20A and 20B are applied to the surface of the insulating substrate 10, and after the electronic component 30 is installed, the binder resin is cured by heating.

  The mixed density of the conductive filler in the cured conductive adhesive layers 20A and 20B is lower than the mixed density of the conductive metal powder in the conductive patterns 11A and 11B, and the cured conductive adhesive layers 20A and 20B are cured. The mechanical strength is higher than that of the conductive patterns 11A and 11B, and the peel strength with respect to the insulating substrate 10 is higher in the conductive adhesive layers 20A and 20B than in the conductive patterns 11A and 11B. However, the specific resistance and the sheet resistance are higher in the conductive adhesive layers 20A and 20B than in the conductive patterns 11A and 11B.

  The electronic component 30 is placed on the insulating protrusion 13 such that, for example, a substantially central portion of the lower surface (surface on the Z2 side) 30c of the electronic component 30 faces the insulating protrusion 13, and at this time, the electrodes 31A, The lower surface of 31B is in contact with the conductive adhesive layers 20A and 20B. In addition, the distance L0 between the conductive patterns 11A and 11B is preferably larger than the dimension L1 of the electronic component 30 in the illustrated X1-X2 direction. That is, there is a gap L2 between the side end surface 31A1 of the electrode 31A and the tip of the connection portion 11A1 of the conductive pattern 11A, and the side end surface 31B1 of the electrode 31B and the tip of the connection portion 11B1 of the conductive pattern 11B There is an interval L3 between them. However, as described above, in the region where the electronic component 30 is placed on the insulating substrate 10, if only the conductive adhesive layers 20 </ b> A and 20 </ b> B are interposed in a part of this region, a part of the region is included. The conductive patterns 11A and 11B may slightly enter.

  After the electronic component 30 is placed on the insulating protrusion 13, as shown by the arrow in FIG. 2, when the electronic component 30 is pushed downward and the conductive adhesive layers 20A and 20B are heated, the conductive adhesive layers 20A and 20B are heated. 2 is cured, the position of the lower surface 30c of the electronic component 30 becomes the position of the dotted line in FIG. 2, and the lower surfaces of the electrodes 31A and 31B and the lower surface 30c of the electronic component 30 and the insulating substrate 10 are connected to the conductive adhesive layer 20A, It is fixed via 20B.

  At this time, as shown by the arrows in FIG. 2, the conductive adhesive layer 20A is deformed in the X2 direction shown in the figure, and the conductive adhesive layer 20B is deformed in the X1 direction shown in FIG. Since the insulating protrusions 13 are provided on the insulating substrate 10, the insulating protrusions 13 prevent the conductive adhesive layers 20A and 20B from being integrated. As a result, it is possible to prevent the conductive patterns 11A and 11B from being short-circuited.

  In the present invention, a water repellent made of silicon or the like may be applied on the insulating substrate 10 instead of the insulating protrusions 13. In this case, even when the conductive adhesive layer 20A is deformed in the illustrated X2 direction and the conductive adhesive layer 20B is deformed in the illustrated X1 direction, the conductive adhesive layers 20A and 20B are formed by the water repellent. As a result, the conductive adhesive layers 20A and 20B are prevented from being integrated.

  Further, in the present invention, there is a gap L2 between the side end face 31A1 of the electrode 31A and the tip end portion of the connection portion 11A1 of the conductive pattern 11A, and the side end face 31B1 of the electrode 31B and the connection portion 11B1 of the conductive pattern 11B. There is a space L3 between the tip portion. For this reason, if a large amount of the conductive adhesive layers 20A and 20B are applied, when the electronic component 30 is pushed downward, the conductive adhesive layer 20A moves upward (shown by an arrow in FIG. 2). Z1 direction), and as shown by the dotted line in FIG. 2, the side end face 31A1 of the electrode 31A is covered from the X1 direction shown in FIG. 2, and the conductive adhesive layer 20B also rises upward as shown by the arrow in FIG. As shown by the dotted line, the side end surface 31B1 of the electrode 31B is covered from the X2 direction in the figure. For this reason, the electronic component 30 is fixed from below and from the side by the conductive adhesive layers 20A and 20B. As a result, the electronic component 30 can be reliably fixed by the conductive adhesive layers 20A and 20B, and the electronic component 30 can be prevented from coming off even when an impact is applied from the outside. it can.

  In the present invention, only the conductive adhesive layers 20A and 20B are interposed between the lower surface 30c of the electronic component 30 and the insulating substrate 10, as shown in FIG. There is a space L2 between the side end face 31A1 of the electrode 31A and the tip of the connecting portion 11A1 of the conductive pattern 11A, and the side end face 31B1 of the electrode 31B and the tip of the connecting portion 11B1 of the conductive pattern 11B There is an interval L3 between them.

  For this reason, for example, when a peeling force acts on the electronic component 30, the peeling force is not directly transmitted to the conductive patterns 11A and 11B, and the conductive patterns 11A and 11B are hardly peeled off. Further, the electronic component 30 is firmly fixed to the surface of the insulating substrate 10 by the conductive adhesive layers 20A and 20B.

The partial top view which shows the electronic component mounting board of this invention, FIG. 2 is a sectional view taken along line 2-2 in FIG. FIG. 3A is a plan view showing a conventional method for attaching a chip-type electronic component to a substrate, and FIG. 3B is a cross-sectional view taken along line 3-3 in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Insulation board | substrate 11A, 11B Conductive pattern 11A1, 11B1 Connection part 11A2, 11B2 Wiring part 13 Insulation protrusion 20A, 20B Conductive adhesive layer 30 Electronic component 31A, 31B Electrode L2, L3 Space | interval

Claims (3)

In the electronic component mounting substrate in which a conductive pattern having conductive metal powder and a binder resin is formed on the surface of the insulating substrate, and the electronic component mounted on the insulating substrate is in conduction with the conductive pattern,
On the surface of the insulating substrate, there is provided a conductive adhesive layer having a conductive filler and a binder resin, and the density of the conductive filler is lower than that of the conductive pattern. Formed without interposing the conductive pattern on the surface of the substrate and electrically connected to the conductive pattern;
The electronic component mounting substrate, wherein the electronic component is installed on the conductive adhesive layer, and the electronic component and the insulating substrate are fixed via the conductive adhesive layer.   On the insulating substrate, a pair of conductive patterns are provided opposite to each other, and a pair of conductive adhesive layers are formed between the end portions of the pair of conductive patterns with a space therebetween. The electronic component mounting board according to claim 1, wherein each of both end portions of the electronic component is disposed on the conductive adhesive layer.   The electronic component mounting board according to claim 2, wherein an insulating protrusion protruding from the insulating substrate is provided between the two conductive adhesive layers.

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