JP4832147B2 - Circuit board connection structure and electronic equipment - Google Patents

Description

  The present invention relates to a circuit board connection structure in which a soft circuit board and a hard circuit board are connected to each other with an anisotropic conductive adhesive by pressing them while heating them in the thickness direction, the soft circuit board, the hard circuit board, and the circuit board The present invention relates to a connection method and an electronic device.

  As a circuit board connection structure, a soft circuit board and a hard circuit board are provided, and the soft circuit board and the hard circuit board are made of an anisotropic conductive adhesive by pressing the soft circuit board and the hard circuit board with a pressure welding jig while heating each other in the thickness direction. What is connected is known.

  In this circuit board connection structure, for example, a through hole penetrating both sides is formed in a soft base material of a soft circuit board, a via is provided on the inner wall of the through hole, and a circuit pattern on one side is made using this via. And a connecting portion on the other surface are connected, and the soft circuit board is connected to the hard circuit board with a pressure welding jig to be connected with an anisotropic conductive adhesive.

Specifically, a cylindrical via is formed by guiding solder to the through hole, and one end of this via is connected to the disc-shaped end (disk portion) of the circuit pattern, and the other end of the via is connected to the disc-shaped connection portion. By connecting to the end portion (disk portion), the circuit pattern on one surface and the connection portion on the other surface are connected by vias (for example, Patent Document 1).
JP 2004-31555 A

By the way, when the soft circuit board and the hard circuit board are heated and pressed with the pressure welding jig, only the soft base material of the soft circuit board is compressed in the thickness direction, leaving a cylindrical via that is not easily crushed in the axial direction.
Therefore, the end portion of the via protrudes relatively from the disk portion of the circuit pattern on the soft circuit board, and as a result, there is a possibility that a crack may occur between the disk portion of the circuit pattern and the via.
Such a phenomenon may occur in the disk part of the connection part as well.

Further, in order to connect the circuit pattern and the connection portion with vias, a disk portion is required for the circuit pattern and the connection portion. Since the disk portion has a larger diameter than the circuit pattern and the width of the connection portion, a plurality of circuit patterns and a plurality of connection portions cannot be densely arranged along the arrangement direction.
Specifically, if the dimension between the centers of each circuit pattern and each connection part does not exceed the diameter dimension of the disk part, adjacent disk parts interfere.
For this reason, the dimension between centers of each circuit pattern and each connection part cannot be suppressed small.

The present invention has been made to solve the above-described conventional problems. The first object of the present invention is to provide a circuit board connection structure, a soft circuit board, and a hard circuit board that are less likely to crack in the disk portion even when heated and pressed. The object is to provide a circuit board, a circuit board connection method, and an electronic apparatus.
The second object of the present invention is to provide a circuit board connection structure, a soft circuit board, a hard circuit board, a circuit board connection method, and an electronic apparatus, in which each second circuit pattern and each soft second connection portion can be closely arranged. Is to provide.

  The circuit board connection structure of the present invention includes a first circuit pattern provided on a surface of a soft base material, a second circuit pattern provided at a location other than the surface of the soft base material, and the soft base material. A soft-side first connection portion provided on the surface and connected to the first circuit pattern; and the second circuit pattern via a via that is adjacent to the first connection portion and penetrates the soft base material in the thickness direction. A soft circuit board having a soft side second connection portion coupled to the hard base, and adjacently arranged on the surface of the hard base, and individually with respect to the soft side first connection portion and the soft side second connection portion A hard circuit board having a hard-side first connection portion and a hard-side second connection portion that are surface-connected, and the soft-side first connection portion and the soft-side second connection via an anisotropic conductive adhesive Said hard side first with respect to each part A circuit board connection structure connected by pressing the soft circuit board and the hard circuit board while heating them in the thickness direction with the connecting part and the hard side second connection part facing each other, A buffer portion is provided on the extension along the through direction of the via so as to relieve the pressure contact force corresponding to the projected contour shape of the via.

A buffer portion for relaxing the pressure contact force corresponding to the projected contour shape of the via is provided on the extension along the via penetration direction. Therefore, when the soft circuit board and the hard circuit board are pressed against each other while being heated in the thickness direction, the pressing force acting on the via can be reduced.
Thus, the soft circuit board and the hard circuit board can be satisfactorily connected with the anisotropic conductive adhesive by uniformly pressing and pressing the anisotropic conductive adhesive.

  In addition, by reducing the pressure contact force acting on the via, it becomes possible to apply a good pressure contact force to the disk part of the second circuit pattern and the disk part of the soft second connection part, and there is a crack in the disk part. It can be prevented from occurring.

  Further, the present invention is characterized in that the buffer portion is provided by disposing the hard-side second connection portion outside the projected contour of the via.

The buffer portion is a space that is formed in a portion corresponding to the projected contour shape 32 of the via 24 by disposing the second hard side connection portion outside the projected contour of the via.
Therefore, when the soft circuit board and the hard circuit board are brought into pressure contact with each other while being heated in the thickness direction, the pressure contact force acting on the via can be reduced by accommodating the via in the buffer portion.
Thus, the soft circuit board and the hard circuit board can be satisfactorily connected with the anisotropic conductive adhesive by uniformly pressing and pressing the anisotropic conductive adhesive.

  In addition, by accommodating the via in the buffer part and reducing the pressure contact force acting on the via, it is possible to apply a good pressure contact force to the disk part of the second circuit pattern and the disk part of the soft second connection part. It can prevent that a crack arises in a disk part.

  Furthermore, this invention has a soft coating layer which covers the back surface of the said soft base material, The said buffer part is a through-hole provided in the position corresponding to the projection outline of the said via in the said coating layer. Features.

The buffer portion is a through hole provided at a position corresponding to the projected contour of the via in the coating layer.
Therefore, when the soft circuit board and the hard circuit board are brought into pressure contact with each other while being heated in the thickness direction, the pressure contact force acting on the via can be reduced by accommodating the via in the through hole.
Thus, the soft circuit board and the hard circuit board can be satisfactorily connected with the anisotropic conductive adhesive by uniformly pressing and pressing the anisotropic conductive adhesive.

  In addition, by accommodating the via in the through hole and reducing the pressure contact force acting on the via, it is possible to apply a good pressure contact force to the disk portion of the second circuit pattern and the disk portion of the soft second connection portion. It can prevent that a crack arises in a disk part.

  Further, the present invention is characterized in that the buffer portion is a recess provided in the hard-side second connection portion corresponding to the projected contour of the via.

A buffer part is a recessed part provided in the hard side 2nd connection part corresponding to the projection outline of via | veer.
Therefore, when the soft circuit board and the hard circuit board are brought into pressure contact with each other while being heated in the thickness direction, the pressure contact force acting on the via can be reduced by accommodating the via in the recess.
Thus, the soft circuit board and the hard circuit board can be satisfactorily connected with the anisotropic conductive adhesive by uniformly pressing and pressing the anisotropic conductive adhesive.

  In addition, by accommodating the via in the recess and reducing the pressure contact force acting on the via, it is possible to apply a good pressure contact force to the disk part of the second circuit pattern and the disk part of the soft second connection part. Therefore, it is possible to prevent cracks from occurring in the disk portion.

  Furthermore, the present invention is characterized in that the buffer portion is a through-hole provided in the hard-side second connection portion corresponding to the projected contour of the via.

A buffer part is a through-hole provided in the hard side 2nd connection part corresponding to the projection outline of a via.
Therefore, when the soft circuit board and the hard circuit board are brought into pressure contact with each other while being heated in the thickness direction, the pressure contact force acting on the via can be reduced by accommodating the via in the through hole.
Thus, the soft circuit board and the hard circuit board can be satisfactorily connected with the anisotropic conductive adhesive by uniformly pressing and pressing the anisotropic conductive adhesive.

  In addition, by accommodating the via in the through hole and reducing the pressure contact force acting on the via, it is possible to apply a good pressure contact force to the disk portion of the second circuit pattern and the disk portion of the soft second connection portion. It can prevent that a crack arises in a disk part.

An electronic apparatus according to the present invention is characterized in that the circuit board connection structure is housed in a housing.

According to the circuit board connection structure, the soft circuit board, the hard circuit board, the circuit board connection method, and the electronic device of the present invention, the disk portion is cracked by relaxing the pressure contact force acting on the via during the heat pressure welding. It has the effect that it is hard to produce.
Furthermore, according to the circuit board connection structure, the soft circuit board, the hard circuit board, the circuit board connection method, and the electronic apparatus according to the present invention, the lines intersecting the vias with respect to the arrangement direction of the soft side second connection portions. By arranging them in a zigzag pattern, the second circuit patterns and the soft second connection portions can be densely arranged.

(First embodiment)
As shown in FIG. 1, in the electronic device 10 according to the first embodiment, a circuit board connection structure 12 is housed in a housing 11.
Examples of the electronic device 10 include a portable terminal such as an electronic device, but are not limited thereto.

  As shown in FIGS. 1 and 2, the circuit board connection structure 12 according to the first embodiment includes a soft circuit board 15 and a hard circuit board 16, and the soft circuit board 15 and the hard circuit board 16 are formed to have a thickness. It connects with the anisotropic conductive adhesive 17 by making it press-contact, heating in a direction.

  The soft circuit board 15 includes a first circuit pattern 21 provided on the front surface 20A of the soft base material 20, and a second circuit pattern 22 provided on a portion (for example, the back surface) 20B other than the front surface 20A of the soft base material 20. A soft-side first connection portion 23 provided on the surface 20A of the soft base material 20 and connected to the first circuit pattern 21, and adjacent to the first connection portion 23 and penetrates the soft base material 20 in the thickness direction. And a soft-side second connection portion 25 connected to the second circuit pattern 22 via the via 24.

  In the soft circuit board 15, a soft coverlay (covering layer) 26 is provided on the back surface 20 </ b> B of the soft base material 20. The coverlay 26 is a layer for protecting the via 24 and the like by covering the back surface 20B.

The via 24 is solder that is provided on the peripheral wall of the through hole 20C and formed in a cylindrical shape. The through hole 20 </ b> C is a through hole formed in the soft base material 20.
The via 24 has an upper portion 24A electrically connected to the end portion 22A of the second circuit pattern 22 and a lower portion 24B electrically connected to the end portion 25A of the soft-side second connection portion 25.

As shown in FIGS. 2 and 3, the second circuit pattern 22 has an end portion 22 </ b> A formed in a disk shape (hereinafter referred to as “disk portion 22 </ b> A”).
The disk portion 22 </ b> A needs to be formed with an outer shape larger than the outer shape of the via 24, and the diameter dimension D shown in FIG. 2 is formed larger than the width dimension W of the second circuit pattern 22.

As shown in FIGS. 2 and 3, the soft second connecting portion 25 has a disc portion 25 </ b> A at the end.
The disk portion 25 </ b> A needs to have an outer shape larger than the outer shape of the via 24, and the diameter dimension D shown in FIG. 2 is larger than the width dimension W of the second circuit pattern 25.

As shown in FIG. 2, the soft circuit board 15 has a plurality of soft side second connection portions 25, and each soft side second connection portion 25 is arranged along the width direction (arrow A-B direction). In addition, each via 24 connected to each soft side second connection portion 25 is along an intersecting line (intersecting line) 27 that intersects the arrangement direction (arrow W direction) of each soft side second connection portion 25. Are arranged.
Thereby, each via | veer 24 can be arrange | positioned in what is called a staggered pattern.

Thus, by arranging the vias 24 in a staggered manner, the distance D between the centers of the adjacent soft-side second connection portions 25 can be kept small without causing the adjacent disk portions 25A to interfere with each other.
Similarly, by arranging the vias 24 in a staggered manner, the distance D between the centers of the adjacent second circuit patterns 22 can be kept small without causing the adjacent disk portions 22A to interfere.
Thereby, each 2nd circuit pattern 22 and each soft side 2nd connection part 25 can be arranged closely.

  As shown in FIG. 1, the hard circuit board 16 is adjacently disposed on the surface 28 </ b> A of the hard base 28 in order to connect to the soft circuit board 15, and the soft side first connection portion 23 and the soft side second connection are provided. The hard side first connection part 30 and the hard side second connection part 31 that are individually surface-connected to the part 25 are provided.

The circuit board connection structure 12 is provided with a buffer portion 33 for relaxing the pressure contact force corresponding to the projected contour shape 32 of the via 24 on the extension along the through direction of the via 24.
The buffer portion 33 is provided by disposing the hard-side second connection portion 31 outside the projected contour 32 of the via 24.
Specifically, the buffer portion 33 provides the hard-side second connection portion 31 with the end portion 31A of the hard-side second connection portion 31 removed from the projection contour 32 of the via 24 to the outside. This is a space formed in the corresponding part of the projected contour shape 32.

  The circuit board connection structure 12 includes a hard side first connection portion 30 and a hard side first connection portion with respect to the soft side first connection portion 23 and the soft side second connection portion 25 through an anisotropic conductive adhesive 17. With the two connecting portions 31 facing each other, the soft circuit board 15 and the hard circuit board 16 are connected by being pressed against each other while being heated in the thickness direction using a pair of upper and lower pressure jigs 35. .

Next, a process of manufacturing the circuit board connection structure 12 according to the first embodiment will be described with reference to FIGS.
As shown in FIG. 3, a buffer portion 33 is provided as a space in a portion corresponding to the projected contour shape 32 (see FIG. 1) of the via 24 on the extension along the penetration direction of the via 24 in advance.
In this state, the soft circuit board 20 and the hard circuit board 16 are set on the upper and lower pressure jigs 35.

That is, the hard side first connection part 30 and the hard side second connection part with respect to the soft side first connection part 23 and the soft side second connection part 25 through the anisotropic conductive adhesive 17 shown in FIG. 31 face each other.
Thereafter, the soft circuit board 20 is lowered as shown by an arrow and placed on the hard circuit board 16. As a result, the anisotropic conductive adhesive 17 is sandwiched between the soft circuit board 20 and the hard circuit board 16.

As shown in FIG. 4, the soft circuit board 20 and the hard circuit board 16 are pressed against each other using a pair of pressure jigs 35 while being heated in the thickness direction.
At this time, it is conceivable that the thickness dimension of the soft base material 20 is reduced by heating and pressing with the pair of pressure jigs 35. On the other hand, the cylindrical via 24 is a member that is not easily crushed.

Here, a buffer portion 33 is provided as a space in a portion corresponding to the projected contour shape 32 of the via 24 on the extension along the penetration direction of the via 24.
Therefore, the lower portion 24 </ b> B of the via 24 protruding from the surface 20 </ b> A of the soft base material 20 is accommodated in the buffer portion 33.
Thus, when the soft circuit board 20 and the hard circuit board 16 are heated and pressed by the pair of pressurizing jigs 35, the anisotropic conductive adhesive 17 is pressed and pressed evenly to soft the circuit board 20 and the hard circuit board. 16 can be satisfactorily connected by the anisotropic conductive adhesive 17.

  In addition, by accommodating the lower part 24B of the via 24 in the buffer part 33, it is possible to satisfactorily apply a pressure contact force to the disk part 22A of the second circuit pattern 22 and the disk part 25A of the soft second connection part 25. Thus, cracks can be prevented from occurring in the disk portions 22A and 25A.

  Next, a circuit board connection structure according to the second to third embodiments will be described with reference to FIGS. In the second to third embodiments, the same members as those of the circuit board connection structure 12 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

(Second Embodiment)
The circuit board connection structure 40 according to the second embodiment shown in FIGS. 5 and 6 includes the cover lay 26 provided with a buffer 41, and the other configurations are the circuit board connection structure 12 according to the first embodiment. Is the same.
The buffer portion 41 is a hole (through hole) provided at a position corresponding to the projected contour shape 32 of the via 24 in the cover lay 26 and having a diameter dimension larger than that of the projected contour shape 32.

Next, a process of manufacturing the circuit board connection structure 40 according to the second embodiment will be described with reference to FIGS. 5 and 7 to 8.
As shown in FIG. 5, a through hole 41 is provided in advance as a buffer portion in a portion corresponding to the projected contour shape 32 (see FIG. 1) of the via 24 on the extension along the penetration direction of the via 24.
In this state, the soft circuit board 20 and the hard circuit board 16 are set on the upper and lower pressure jigs 35.

That is, the hard-side first connection part 30 and the hard-side second connection part with respect to the soft-side first connection part 23 and the soft-side second connection part 25 through the anisotropic conductive adhesive 17 shown in FIG. 31 face each other.
Thereafter, as shown in FIG. 7, the soft circuit board 20 is lowered as shown by an arrow and placed on the hard circuit board 16. As a result, the anisotropic conductive adhesive 17 is sandwiched between the soft circuit board 20 and the hard circuit board 16.

As shown in FIG. 8, the soft circuit board 20 and the hard circuit board 16 are pressed against each other using a pair of pressure jigs 35 while being heated in the thickness direction.
At this time, it is conceivable that the thickness dimension of the soft base material 20 is reduced by heating and pressing with the pair of pressure jigs 35. On the other hand, the cylindrical via 24 is a member that is not easily crushed.

Here, a through hole 41 is provided in a portion corresponding to the projected contour shape 32 of the via 24 on an extension along the through direction of the via 24.
Therefore, the upper portion 24 </ b> A of the via 24 protruding from the surface 20 </ b> A of the soft base material 20 is accommodated in the through hole 41.
Thus, when the soft circuit board 20 and the hard circuit board 16 are heated and pressed by the pair of pressurizing jigs 35, the anisotropic conductive adhesive 17 is pressed and pressed evenly to soft the circuit board 20 and the hard circuit board. 16 can be satisfactorily connected by the anisotropic conductive adhesive 17.

  In addition, by accommodating the upper portion 24A of the via 24 in the through hole 41, it is possible to satisfactorily apply a pressure contact force to the disc portion 22A of the second circuit pattern 22 and the disc portion 25A of the soft second connection portion 25. Thus, cracks can be prevented from occurring in the disk portions 22A and 25A.

  That is, according to the circuit board connection structure 40 according to the second embodiment, the same effect as the circuit board connection structure 12 according to the first embodiment can be obtained.

(Third embodiment)
The circuit board connection structure 50 according to the third embodiment shown in FIGS. 9 and 10 is provided with a through hole as a buffer portion 51 in the hard-side second connection portion, and the other configurations according to the first embodiment. This is the same as the circuit board connection structure 12.
The through hole 51 is provided at a position corresponding to the projected contour shape 32 of the via 24 in the hard-side second connection portion, and has a diameter larger than that of the projected contour shape 32.

Next, a process of manufacturing the circuit board connection structure 50 according to the third embodiment will be described with reference to FIGS.
11A to 11C show a state in which the anisotropic conductive adhesive 17 is omitted in order to easily understand the role of the through hole 51.
As shown in FIG. 10, a through hole 51 is provided in advance as a buffer portion in a portion corresponding to the projected contour shape 32 (see FIG. 1) of the via 24 on the extension along the penetration direction of the via 24.
In this state, the soft circuit board 20 and the hard circuit board 16 are set on the upper and lower pressure jigs 35.

That is, the hard side first connection part 30 and the hard side second connection part with respect to the soft side first connection part 23 and the soft side second connection part 25 through the anisotropic conductive adhesive 17 shown in FIG. 31 face each other.
Thereafter, the soft circuit board 20 is lowered as shown by an arrow and placed on the hard circuit board 16. As a result, the state shown in FIG. 11A is changed to the state shown in FIG.

As shown in FIG. 12, the soft circuit board 20 and the hard circuit board 16 are pressed against each other using a pair of pressure jigs 35 while being heated in the thickness direction.
At this time, it is conceivable that the thickness dimension of the soft base material 20 is reduced by heating and pressing with the pair of pressure jigs 35. On the other hand, the cylindrical via 24 is a member that is not easily crushed.

Here, a through hole 51 is provided in a portion corresponding to the projected contour shape 32 of the via 24 on an extension along the through direction of the via 24.
Therefore, the upper portion 24A of the via 24 protruding from the surface 20A of the soft base material 20 is accommodated in the through hole 51 (see also FIG. 11C).
Thus, when the soft circuit board 20 and the hard circuit board 16 are heated and pressed by the pair of pressurizing jigs 35, the anisotropic conductive adhesive 17 is pressed and pressed evenly to soft the circuit board 20 and the hard circuit board. 16 can be satisfactorily connected by the anisotropic conductive adhesive 17.

  In addition, by accommodating the upper portion 24 </ b> A of the via 24 in the through hole 51, it is possible to satisfactorily apply a pressure contact force to the disc portion 22 </ b> A of the second circuit pattern 22 and the disc portion 25 </ b> A of the soft second connection portion 25. Thus, cracks can be prevented from occurring in the disk portions 22A and 25A.

  That is, according to the circuit board connection structure 50 according to the third embodiment, the same effect as the circuit board connection structure 12 according to the first embodiment can be obtained.

(Modification)
FIGS. 13A and 13B show a modification of the third embodiment. In this modification, a concave portion 52 is provided instead of the through hole 51 of the hard-side second connection portion 31 according to the third embodiment, and other configurations are the same as the circuit board connection structure 50 according to the third embodiment. The same.
The recess 52 is provided at a position corresponding to the projected contour shape 32 of the via 24 in the hard-side second connection portion 31, and has a diameter dimension larger than that of the projected contour shape 32.
Also in the modification, the same effect as the circuit board connection structure 50 according to the third embodiment can be obtained.

  Note that the shapes and configurations of the buffer portions 33, 41, 51, 52, the vias 24, the projected contour shape 32, and the like exemplified in the above embodiment are not limited to these, and can be changed as appropriate.

  The present invention relates to a circuit board connection structure in which a soft circuit board and a hard circuit board are connected to each other with an anisotropic conductive adhesive by pressing them while heating them in the thickness direction, the soft circuit board, the hard circuit board, and the circuit board Suitable for connection method and application to electronic equipment.

It is sectional drawing which shows the connection structure (1st Embodiment) of the circuit board based on this invention. It is a top view which shows the principal part of the connection structure of the circuit board which concerns on 1st Embodiment. It is a perspective view which shows the connection structure of the circuit board which concerns on 1st Embodiment. It is a figure explaining the effect | action of the connection structure of the circuit board which concerns on 1st Embodiment. It is sectional drawing which shows the connection structure (2nd Embodiment) of the circuit board based on this invention. It is a perspective view which shows the principal part of the connection structure of the circuit board which concerns on 2nd Embodiment. It is a perspective view which shows the connection structure of the circuit board which concerns on 2nd Embodiment. It is a figure explaining the effect | action of the connection structure of the circuit board which concerns on 2nd Embodiment. It is sectional drawing which shows the connection structure (3rd Embodiment) of the circuit board based on this invention. It is a perspective view which shows the connection structure of the circuit board which concerns on 3rd Embodiment. It is a figure explaining the effect | action of the principal part with which the circuit board connection structure which concerns on 3rd Embodiment was equipped. It is a figure explaining the effect | action of the connection structure of the circuit board which concerns on 3rd Embodiment. (A) is a perspective view which shows the modification of the circuit board connection structure concerning 3rd Embodiment, (B) is sectional drawing which shows the modification of the circuit board connection structure concerning 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electronic device 11 Case 12, 40, 50 Circuit board connection structure 15 Soft circuit board 16 Hard circuit board 17 Anisotropic conductive adhesive 20 Soft base material 20A Soft base material surface 22 Second circuit pattern 20B Back surface ( Locations other than the surface)
21 1st circuit pattern 23 Soft side 1st connection part 24 Via 25 Soft side 2nd connection part 26 Coverlay (covering layer)
27 Intersection line (intersecting line)
28 Hard substrate 28A Hard substrate surface 30 Hard side first connection portion 31 Hard side second connection portion 32 Projection contour shape 33, 41, 51, 52 Buffer portion

Claims (6)

A first circuit pattern provided on the surface of the soft substrate; a second circuit pattern provided at a location other than the surface of the soft substrate; and the first circuit pattern provided on the surface of the soft substrate. A soft-side first connection portion connected to the second circuit pattern, and a soft-side second connection portion that is adjacent to the first connection portion and is connected to the second circuit pattern via a via that penetrates the soft base material in the thickness direction. A soft circuit board having
A hard side first connection portion and a hard side second connection portion that are arranged adjacent to each other on the surface of the hard base and are individually surface-connected to the soft side first connection portion and the soft side second connection portion. A hard circuit board having
With the hard side first connection part and the hard side second connection part facing each other with respect to the soft side first connection part and the soft side second connection part via an anisotropic conductive adhesive, A circuit board connection structure connected by pressing the soft circuit board and the hard circuit board while heating in the thickness direction,
A connection structure for a circuit board, wherein a buffer portion is provided on the extension along the through direction of the via so as to alleviate the pressure contact force corresponding to the projected contour shape of the via.   2. The circuit board connection structure according to claim 1, wherein the buffer portion is provided by disposing the hard-side second connection portion outside a projected contour of the via. 3. Having a soft coating layer covering the back surface of the soft substrate;
The circuit board connection structure according to claim 1, wherein the buffer portion is a through-hole provided at a position corresponding to a projected contour of the via in the coating layer.   The circuit board connection structure according to claim 1, wherein the buffer portion is a concave portion provided in the hard-side second connection portion corresponding to a projected contour of the via. 2. The circuit board connection structure according to claim 1 , wherein the buffer portion is a through hole provided in the hard-side second connection portion corresponding to a projected contour of the via. Electronic device connection structure for a circuit board as set forth in any one of claims 1 to 5, characterized in that it is accommodated in the housing.

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