JP2007318021A - Connection structure of wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To greatly reinforce a joined part of connecting terminals and to increase its reliability. <P>SOLUTION: This is a connection structure of a wiring board wherein connecting terminals 5 and 14 exposed on insulating substrates 2 and 11 are formed onto a rigid board 1 and a flexible board 10, respectively, these two connecting terminals 5 and 14 are directly bonded with each other, and a place that is outside the rigid board 1 and the flexible board 10 corresponding to the bonded place of the two connecting terminals 5 and 14 is covered by a heat shrinkable tube 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wiring board connection structure for directly connecting connection terminal portions of two wiring boards.

  Conventionally, there is a connection method using a connector as a method for connecting a flexible substrate and a rigid substrate. However, in the connection method using a connector, a separate member called a connector is interposed, resulting in a high component cost. In addition, since it occupies a two-dimensional or three-dimensional space, it is disadvantageous for high density mounting. For example, a technique disclosed in Patent Document 1 is known as a technique for directly connecting the connection terminal portions of two wiring boards without using a connector.

  As shown in FIG. 15, this wiring board connection structure has two wiring boards 100 and 110. Each wiring board 100 and 110 has a plurality of connections formed on one surface of the insulating boards 101 and 111. Terminal portions 102 and 112 are provided. Both wiring boards 100 and 110 are abutted, and the corresponding connecting terminal portions 102 and 112 are joined by ultrasonic welding. Underfill 120 is filled in the gaps between the plurality of connection terminal portions 102 and 112 that are joined.

In this conventional connection structure, the bonding strength at the bonding location of both wiring boards 100 and 110 is the bonding strength of both connection terminal portions 102 and 112 and the adhesion strength of the underfill 120 to each insulating substrate 101 and 111. Depends on. That is, the bonding strength is enhanced by the underfill 120.
JP 2005-209704 A

  However, since the adhesion force of the underfill 120 to the insulating substrates 101 and 111 is not strong, the strength cannot be increased greatly as reinforcement.

  Further, the underfill 120 is difficult to manage the resin filling range, and bubbles are easily generated in the filled resin. For this reason, the reinforcement by the underfill 120 tends to cause variations in strength, and a highly reliable reinforcement cannot be performed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a wiring board connection structure that reinforces the joint portion of the connection terminal portion with a great increase in strength and is highly reliable.

  The present invention relates to a wiring board connection structure, wherein a connection terminal portion is formed on each insulating substrate of a pair of wiring boards, and the connection terminal portions of the pair of wiring boards are directly joined to each other. However, the gist is that the joint portion between the wiring boards is covered with a heat shrinkable tube.

  According to the present invention, the heat-shrinkable tube reinforces the joining of both connection terminal portions by the restraining force that restrains both the wiring boards from the outside, so that the strength is greater than the reinforcement by the adhesion force of the underfill to the insulating board. Can be increased. Moreover, since the heat-shrinkable tube is easy to manage during the covering range and covering operation, it is difficult for the strength to vary, and it is possible to reinforce with higher reliability than underfill. In particular, since the heat-shrinkable tube shrinks immediately when heated, the reinforcing work time may be short. Furthermore, since the heat-shrinkable tube covers the outside of both insulating substrates, the reinforcing state by the heat-shrinkable tube can be visually confirmed from the outside.

  Hereinafter, details of a connection structure for a wiring board according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic and the thicknesses and ratios of the material layers are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

(First embodiment)
1 to 4 show a first embodiment of the present invention, FIG. 1 is an exploded perspective view of a wiring board connection structure, FIG. 2 is a perspective view of the wiring board connection structure, and FIG. 3 is A1 in FIG. -A1 sectional view, FIG. 4 is a B1-B1 sectional view of FIG.

  As shown in FIGS. 1 to 4, the wiring board connection structure is generally composed of a rigid board 1 that is one wiring board, a flexible board 10 that is the other wiring board, and a heat shrinkable tube 20.

  The rigid substrate 1 includes an insulating substrate 2, a plurality of wiring patterns 3 formed on the one surface, and a protective layer provided on the surface of the insulating substrate 2 on which the plurality of wiring patterns 3 are formed via an adhesive layer (not shown). And a resist layer 4 as a layer.

  As shown in FIG. 1, a connection region S <b> 1 where the resist layer 4 does not exist is formed on the surface of the insulating substrate 2. In this connection region S1, a plurality of connection terminal portions 5 are formed by a part of the wiring pattern 3. The plurality of connection terminal portions 5 are exposed on the insulating substrate 2. The plurality of connection terminal portions 5 are arranged so as to be parallel to each other (side by side).

  In addition, a pair of cuts 6 and 6 are formed in the insulating substrate 2 along the vicinity of both outer sides of the plurality of connection terminal portions 5. The distance between the pair of cuts 6 and 6 is substantially the same as the width of the flexible substrate 10. Further, the depth of the pair of cuts 6 and 6 (depth cut along the planar direction from the edge) reaches a position deeper than the connection region, that is, a position where the resist layer 4 exists.

  The insulating substrate 2 is made of, for example, glass epoxy, SEM3, paper epoxy, or the like. The wiring pattern 3 is formed by patterning a copper foil attached on the insulating substrate 2 by, for example, a subtractive method. As the adhesive layer (not shown), for example, various resin adhesives such as polyimide, epoxy, and olefin can be used.

  The flexible substrate 10 includes an insulating substrate 11, a plurality of wiring patterns 12 formed on the one surface, and a coverlay 13 that is a protective layer provided on the surface of the insulating substrate 11 on which the plurality of wiring patterns 12 are formed. It has.

  As shown in FIG. 1, a connection region S <b> 2 where the cover lay 13 does not exist is formed on the surface of the end portion of the insulating substrate 11. A plurality of connection terminal portions 14 are formed by the end portions of the wiring pattern 12 in the connection region S2. The plurality of connection terminal portions 14 are exposed on the insulating substrate 11. The plurality of connection terminal portions 14 are arranged so as to be parallel to each other (side by side).

  As a constituent material of the insulating substrate 11, for example, polyimide, PEN (polyethylene naphthalate), PET (polyethylene terephthalate), or the like can be used.

  The rigid substrate 1 and the flexible substrate 10 have both connection regions S1 and S2 abutted against each other, and the corresponding connection terminal portions 5 and 14 are joined together by soldering or the like.

  The heat-shrinkable tube 20 is disposed between the outer periphery of the flexible substrate 10 and the pair of cuts 6 and 6 of the rigid substrate 1, so that the heat-shrinkable tube 20 is disposed on the outer periphery of the joint portion where the connection terminal portions 5 and 14 are joined. Yes. Then, by being thermally contracted at this position, the joint location where both the connection terminal portions 5, 14 are joined and the periphery thereof are covered from the outside of both the insulating substrates 2, 11.

  The heat-shrinkable tube 20 is set such that the length dimension L1 when contracted is longer than the total dimension L2 of the connection regions S1, S2 of both the rigid substrate 1 and the flexible substrate 10. As a result, the heat shrinkable tube 20 covers the resist layer 4 and the coverlay 13 that protect the wiring patterns 3 and 12 as well as the portions where the connection terminal portions 5 and 14 on the insulating substrates 2 and 11 are exposed.

  Next, an outline of connection work between the rigid substrate 1 and the flexible substrate 10 will be described. First, the connection regions S1 and S2 of both the rigid substrate 1 and the flexible substrate 10 are brought into contact with each other, and both corresponding connection terminal portions 5.14 are brought into contact with each other. They are joined by soldering. Next, the heat shrinkable tube 20 is passed through the outer periphery of the flexible substrate 10 or the heat shrinkable tube 20 previously placed through the outer periphery of the flexible substrate 10 is inserted into the pair of cuts 6 and 6 of the rigid substrate 1 to heat shrink. The tube 20 is positioned on the outer periphery of the joint portion between the connection terminal portions 5 and 14.

  Next, the heat shrinkable tube 20 is heated. Then, the heat-shrinkable tube 20 is heat-shrinked, and the joint location where both the connection terminal portions 5 and 14 are joined by the heat-shrinkable heat-shrinkable tube 20 and the periphery thereof are covered from the outside of both the insulating substrates 2 and 11. . This completes the connection work.

  In the connection structure of the wiring board described above, the joint portion of the rigid board 1 and the flexible board 10 is covered with the heat shrinkable tube 20. Therefore, the heat shrink tube 20 reinforces the joining of the connection terminal portions 5 and 14 by the restraining force that restrains the rigid substrate 1 and the flexible substrate 10 from the outside, so that the conventional underfill adheres to the insulating substrate. Compared with reinforcement, the strength can be greatly increased. And since the heat shrinkable tube 20 is easy to manage during the covering range and covering operation, it is difficult for the strength to vary, and it is possible to reinforce with higher reliability than underfill.

  Moreover, since the heat-shrinkable tube 20 contracts immediately when heated, the reinforcing work time can be shortened. In the conventional example, since it takes time until the resin is cured after filling the underfill, the reinforcement work time is long, but in the present invention, the reinforcement work is completed in a short time.

  Furthermore, since the heat-shrinkable tube 20 covers the outer sides of both insulating substrates 2 and 11, the state of reinforcement by the heat-shrinkable tube 20 can be visually confirmed from the outside. In the conventional example, since the underfill is filled between the connection terminal portions, the reinforcing state by the underfill cannot be visually confirmed from the outside, but in the present invention, the reinforcing state can be visually confirmed.

  Moreover, since the thickness and material of the heat shrinkable tube 20 can basically be freely selected, a desired strength can be easily ensured. In addition, it is also possible to install a plurality of heat-shrinkable tubes 20 in an overlapping manner, and a desired strength can be easily ensured by such an overlapping structure.

  In the present embodiment, the insulating substrate 2 of the rigid substrate 1 is provided with a pair of cuts 6 and 6 along the vicinity of both outer sides of the plurality of connection terminal portions 5. Accordingly, if the joint portions of the connection terminal portions 5 and 14 are constrained by the heat shrink tube 20 inserted into the pair of cuts 6 and 6, only the joint portions of the connection terminal portions 5 and 14 can be restrained by the heat shrink tube 20. . Accordingly, the dispersion of the restraining force of the heat-shrinkable tube 20 can be prevented, and the restraining force can be increased at the joining location of the heat connection terminal portions 5 and 14. If the pair of cuts 6 and 6 are formed in a wiring board (rigid board 1 in the present embodiment) having a sufficiently small width of the connection region S1 in which the connection terminal portion 5 is arranged compared to the width of the insulating board 2, It is effective.

  In the present embodiment, the heat-shrinkable tube 20 is connected to the resist layer 4 and the coverlay 13 that protect the wiring patterns 3 and 12 together with the portions where the plurality of connection terminal portions 5 and 14 on the insulating substrates 2 and 11 are exposed. It is configured to cover. Therefore, the exposed portions of the connection terminal portions 5 and 14 on the insulating substrates 2 and 11 can be completely covered with the heat shrinkable tube 20, so that the migration resistance can be improved. Further, since the heat-shrinkable tube 20 restrains the resist layer 4 and the cover lay 13, that is, the periphery of the joint portion of both, the strength can be further improved.

  As in the present embodiment, when one is a rigid substrate and the other is a flexible substrate, the rigid substrate serves as a reinforcing plate, and the connection portion is curled or warped by the force due to the contraction of the heat-shrinkable tube 20. There is nothing to do. Thus, when at least one of the pair of wiring boards is a rigid board, the rigidity of the connecting portion can be maintained without using a reinforcing plate.

(Second Embodiment)
5 to 8 show a second embodiment of the present invention, FIG. 5 is an exploded perspective view of the wiring board connection structure, FIG. 6 is a perspective view of the wiring board connection structure, and FIG. 7 is A2 in FIG. -A2 sectional view, FIG. 8 is a B2-B2 sectional view of FIG.

  As shown in FIG. 5 to FIG. 8, the wiring board connection structure includes a rigid board 1 that is one wiring board, a flexible board 10 that is the other wiring board, a heat-shrinkable tube 20, and the bottom surface of the rigid board 1. The reinforcing plate 21 is generally composed of That is, as compared with the first embodiment, the reinforcing plate 21 is disposed on the lower surface of the joint portion of the rigid substrate 1, and the reinforcing plate 21 is covered with the heat shrinkable tube 20 together with both the substrates 1 and 10. Is different.

  Since other configurations are the same as those of the first embodiment, the same reference numerals are given to the same components in the drawings, and description thereof will be omitted.

  In the present embodiment, it is possible to improve the bending rigidity of the joint portion of the connection terminal portions 4 and 14. The reinforcing plate 21 may be disposed on both the rigid substrate 1 side and the flexible substrate 10 side. Further, the attachment of the reinforcing plate 21 is particularly effective when both wiring boards are flexible boards.

(Third embodiment)
9 to 12 show a third embodiment of the present invention, FIG. 9 is an exploded perspective view of the connection structure of the wiring board, FIG. 10 is a perspective view of the connection structure of the wiring board, and FIG. 11 is A3 of FIG. -A3 sectional view, FIG. 12 is a B3-B3 sectional view of FIG.

  As shown in FIG. 9 to FIG. 12, the wiring board connection structure includes a rigid board 1 that is one wiring board, a flexible board 10 that is the other wiring board, a heat shrinkable tube 20, and an underfill 22. Generally composed. That is, as compared with the first embodiment, a difference is that the gaps between the plurality of connection terminal portions 5 and 14 are filled with the underfill 22.

  Since other configurations are the same as those of the first embodiment, the same reference numerals are given to the same components in the drawings, and description thereof will be omitted.

  In this embodiment, since the reinforcement by the underfill 22 is added, the strength can be further increased. Further, the migration resistance characteristics of the joint portions of the connection terminal portions 5 and 14 can be improved.

(Fourth embodiment)
13 and 14 show a fourth embodiment of the present invention, FIG. 13 is an exploded perspective view of a wiring board connection structure, and FIG. 14 is a perspective view of the wiring board connection structure.

  As shown in FIGS. 13 to 14, the insulating substrate 2 of the rigid substrate 1 </ b> A is provided with a protruding portion 2 </ b> A. And the surface of the front end side of this protrusion part 2A is made into connection area | region S1, and the several connection terminal part 5 is arrange | positioned in this connection area | region S1.

  Since other configurations are the same as those of the first embodiment, the same reference numerals are given to the same components in the drawings, and description thereof will be omitted.

  Also in the present embodiment, by inserting the heat-shrinkable tubes 20 on both sides of the protruding portion 2A, as in the first embodiment, only the joint portions of the connection terminal portions 5 and 14 are heat-shrinked. The tube 20 can be restrained. Therefore, dispersion of the restraining force of the heat-shrinkable tube 20 can be prevented, and the restraining force can be increased at the joint portion of the connection terminal portions 5 and 14. The protrusion 2A is effective if formed on a wiring board (rigid board 1A in the present embodiment) in which the width of the connection region S1 in which the connection terminal part 5 is arranged is sufficiently smaller than the width of the insulating substrate 2. is there.

  In each of the above embodiments, the connection terminal portions 5 and 14 are joined by soldering. At the time of this soldering, a solder plating layer is formed on at least one surface of the connection terminal portions 5 and 14, and both ends of the rigid substrate 1 and the flexible substrate 10 are not shown with heater chips (heating pressure head). ) To apply heat and pressure. In each embodiment, bonding is performed using solder plating. However, in addition to solder plating, bonding using lead-containing solder paste, lead-free solder paste, tin plating, or the like, or metal bonding using ultrasonic waves is performed. You may go.

  In each of the embodiments described above, the case where one wiring board is the rigid board 1 or 1A and the other wiring board is the flexible board 10 is shown. Applicable.

It is a disassembled perspective view of the connection structure of the wiring board which concerns on the 1st Embodiment of this invention. 1 is a perspective view of a wiring board connection structure according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line A1-A1 of FIG. FIG. 3 is a cross-sectional view taken along line B1-B1 of FIG. It is a disassembled perspective view of the connection structure of the wiring board which concerns on the 2nd Embodiment of this invention. It is a perspective view of the connection structure of the wiring board which concerns on the 2nd Embodiment of this invention. It is A2-A2 sectional view taken on the line of FIG. FIG. 7 is a sectional view taken along line B2-B2 of FIG. It is a disassembled perspective view of the connection structure of the wiring board which concerns on the 3rd Embodiment of this invention. It is a perspective view of the connection structure of the wiring board which concerns on the 3rd Embodiment of this invention. It is A3-A3 sectional view taken on the line of FIG. It is B3-B3 sectional view taken on the line of FIG. It is a disassembled perspective view of the connection structure of the wiring board which concerns on the 4th Embodiment of this invention. It is a perspective view of the connection structure of the wiring board which concerns on the 4th Embodiment of this invention. It is sectional drawing of the connection structure of the wiring board of a prior art example.

Explanation of symbols

1,1A rigid board (wiring board)
2,11 Insulating substrate 2A Protruding part 3,12 Wiring pattern 4 Resist layer (protective layer)
5,14 Connection terminal part 6 Notch 10 Flexible substrate (wiring substrate)
13 Coverlay (protective layer)
20 Heat shrinkable tube 21 Reinforcement plate 22 Underfill

Claims (7)

A wiring board connection structure in which a connection terminal portion is formed on each insulating substrate of a pair of wiring boards, and the connection terminal portions of the pair of wiring boards are directly joined to each other,
A connection structure for wiring boards, wherein a joint portion between the wiring boards is covered with a heat shrinkable tube.   The wiring board connection structure according to claim 1, wherein one of the pair of wiring boards is a rigid board.   2. The wiring board connection structure according to claim 1, wherein a reinforcing plate is disposed at a joint portion of the pair of wiring boards, and the reinforcing plate is covered with the heat shrinkable tube.   The wiring board connection structure according to any one of claims 1 to 3, wherein an underfill resin is filled in a gap at a joint portion of the pair of wiring boards.   5. The wiring board connection structure according to claim 1, wherein the insulating substrate is provided with cuts in the vicinity of both outer sides of the plurality of connection terminal portions. 6.   5. The wiring according to claim 1, wherein the insulating substrate is provided with a projecting portion along a planar direction, and the connecting terminal portion is formed on the projecting portion. 6. Board connection structure.   The said heat contraction tube comprehensively coat | covers the said insulating substrate, each said connection terminal part, and the protective layer which protects a wiring pattern, The Claim 1 thru | or 6 characterized by the above-mentioned. Wiring board connection structure.

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