JP2007258618A - Connection part reinforcing structure, printed wiring board and connection part reinforcing structure forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connection part reinforcing structure for improving connection strength without increasing the area of a printed wiring board. <P>SOLUTION: The connection part reinforcing structure comprises: a first substrate 10 for which a first wiring pattern 20 with a first connection terminal 22 is provided on a surface 12; a second substrate 30 provided with a center part 32 having a second wiring pattern 40 with a second connection terminal 42 connected to the first connection terminal 22 and an end part 34 bent so as to reach the back surface 14 of the first substrate 10; and a connection reinforcing part 70 connecting the back surface 14 of the first substrate 10 and the end part 34 of the second substrate 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to connection of printed wiring boards, and more particularly to a connection portion reinforcing structure having high connection strength between printed wiring boards, a printed wiring board, and a method of forming a connecting portion reinforcing structure.

  As a method of electrically connecting printed wiring boards such as a rigid board that is rigid and a flexible board that is flexible, there is a method of soldering connection terminal portions of a pair of printed wiring boards. Specifically, a solder layer is provided on the surface of at least one connection terminal portion of the pair of printed wiring boards, and a flux that promotes soldering is applied to overlap the connection terminal portions of both printed wiring boards. In addition, connection is made by applying pressure while heating at a predetermined temperature.

  In recent years, the connection strength between connection terminal portions has become weaker as the wiring pattern of a printed wiring board becomes finer and finer. And when the solder part of a connection terminal part receives the tension | tensile_strength by pulling, the interface of an insulating layer and a conductor layer may peel and may be disconnected. Therefore, a technique is disclosed in which a reinforcing land made of a copper foil land is formed on the inner side of the connection terminal portion on each printed wiring board to be connected, and the connection is strengthened by soldering the reinforcing land at the time of connection. (For example, refer to Patent Document 1).

However, if a reinforcing land is produced on a printed wiring board, the area of the portion for producing the reinforcing land is required, and the substrate becomes larger by the area of the reinforcing land. Therefore, when the size of the reinforcing land is reduced, the reinforcing strength is also reduced. Further, if the reinforcing land is provided to reduce the substrate size, the wiring pattern becomes a narrow pitch.
Japanese Patent Laid-Open No. 5-90725

  An object of this invention is to provide the connection part reinforcement structure which improves connection strength, the printed wiring board, and the connection part reinforcement structure formation method, without enlarging the area of a printed wiring board.

  According to one aspect of the present invention, a first substrate having a first wiring pattern having a first connection terminal provided on the surface and a second wiring pattern having a second connection terminal connected to the first connection terminal are provided. A second substrate having a central portion and an end portion that is bent so as to reach the back surface of the first substrate, and a connection reinforcing portion that connects the back surface of the first substrate and the end portion of the second substrate. The gist is that the structure is reinforced.

  According to another aspect of the present invention, the center part provided with the wiring pattern and the connection reinforcing part for reinforcing the connection strength between the wiring pattern and the wiring pattern of another substrate are provided at both ends of the center part. The gist of the invention is that it is a printed wiring board provided with an end portion.

  According to still another aspect of the present invention, a first substrate having a first wiring pattern having a first connection terminal provided on the surface, and a second wiring pattern having a second connection terminal connected to the first connection terminal. Providing a second substrate having a central portion provided with a first substrate and an end portion reaching the back surface of the first substrate, facing each other so that the first connection terminal and the second connection terminal face each other, and an end portion Includes a step of bending the first substrate so as to hold the first substrate, an end portion reaching the back surface of the first substrate, and a connection reinforcing portion connecting the back surface of the first substrate and the end portion of the second substrate. The gist of the present invention is a method for forming a part reinforcing structure.

  ADVANTAGE OF THE INVENTION According to this invention, the connection part reinforcement structure which improves connection strength, a printed wiring board, and the connection part reinforcement structure formation method can be provided, without enlarging the area of a printed wiring board.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(First embodiment)
In the connection portion reinforcing structure according to the first embodiment of the present invention, as shown in FIGS. 1A and 1B, the first wiring pattern 20 having the first connection terminals 22 is provided on the surface 12. The first substrate 10 and the second connection terminal 42 connected to the first connection terminal 22 are bent so as to reach the central portion 32 provided with the second wiring pattern 40 and the back surface 14 of the first substrate 10. A second substrate 30 having an end portion 34, and a connection reinforcing portion 70 that connects the back surface 14 of the first substrate 10 and the end portion 34 of the second substrate 30 are provided.

  As shown in FIGS. 2A and 2B, the second substrate 30 as the printed wiring board according to the first embodiment of the present invention has a central portion where the second wiring pattern 40 is provided. 32 and a connection reinforcing portion 70 (see FIG. 1B) that reinforces the connection strength between the second wiring pattern 40 and the first wiring pattern 20 of the first substrate 10 is provided at both ends of the central portion 32. And an end 34.

  As the first substrate 10, for example, a rigid rigid substrate such as a glass epoxy substrate, a glass composite substrate, or a paper epoxy substrate can be used. In addition, as the first substrate 10, for example, a flexible substrate having flexibility such as a polyimide substrate, a polyethylene terephthalate (PET) substrate, or a polyethylene naphthalate (PEN) substrate can be used. As the second substrate 30, a flexible substrate is used. Both the first substrate 10 and the second substrate 30 are substrates made of an insulating layer. When a rigid substrate is used, the thickness can be 2.4 mm, 2.0 mm, 1.6 mm, 1.2 mm, 1.0 mm, 0.8 mm, 0.6 mm, or the like. When a flexible substrate is used, the thickness can be 25 μm, 12.5 μm, 8 μm, 6 μm, or the like.

  The first wiring pattern 20 is a conductor circuit pattern designed on the surface 12 of the first substrate 10. Similarly, the second wiring pattern 40 is a conductor circuit pattern designed in the central portion 32 of the second substrate 30. The first wiring pattern 20 and the second wiring pattern 40 are formed on the first substrate 10 and the second substrate 30 by patterning with a rolled copper foil or an electrolytic copper foil. For the first wiring pattern 20 and the second wiring pattern 40, metal foil other than copper foil can be used as a conductor. The pitch width of the first wiring pattern 20 and the second wiring pattern 40 is 10 to 500 μm, and the pattern width is 10 to 500 μm. The thickness of the first wiring pattern 20 and the second wiring pattern 40 can be 35 μm, 18 μm, 12 μm, 9 μm, or the like.

  On the 1st wiring pattern 20 and the 2nd wiring pattern 40, the cover-lay film etc. which made the base material the insulating polyimide film etc. which have the softness | flexibility excellent after adhesion | attachment are arrange | positioned as a cover layer (not shown). . The exposed conductors such as the first connection terminal 22 and the second connection terminal 42 that are not protected by the cover layer are subjected to surface treatment by preflux treatment, hot air leveler (HAL), electrolytic solder plating, electroless solder plating, or the like. Process.

  When the first substrate 10 is a rigid substrate, the first connection terminal 22 is disposed on the inner side with a little space from the end of the substrate. When the first substrate 10 and the second substrate 30 are flexible substrates, respectively, the first connection terminal 22 and the second connection terminal 42 may be arranged at the end of the substrate. The first connection terminal 22 and the second connection terminal 42 may have any shape.

  The connection reinforcement portion 70 includes a reinforcement land 52 provided on the back surface 14 of the first substrate 10, a connection land 54 provided on the end portion 34 of the second substrate 30, and the reinforcement land 52 and the connection land 54. And a connection layer 62 to be connected. The reinforcing land 52 and the connection land 54 are metal foil lands such as copper foil lands. The connection layer 62 that connects the reinforcing land 52 and the connection land 54 is formed by solder bonding, ultrasonic bonding, bonding with a conductive adhesive, or the like.

  As a soldering method, first, solder paste is applied to at least one of the reinforcing land 52 and the connecting land 54, or solder plating is performed. The reinforcing land 52 and the connection land 54 are arranged facing each other, and the connection layer 62 is formed and bonded by heating with a heater such as a heater chip. As a bonding material used for the connection layer 62, lead-containing solder paste, lead-free solder paste, solder plating, tin plating, or the like can be used.

  In the ultrasonic bonding method, first, gold (Au) plating is directly applied to each of the reinforcing land 52 and the connection land 54, or nickel (Ni) plating is applied as a base and then Au plating is applied. Then, the reinforcing land 52 and the connection land 54 are arranged to face each other, and a connection layer 62 is formed and connected by metal bonding by applying ultrasonic waves.

  As a connection method using a conductive adhesive, first, Au plating is directly applied to each of the reinforcing land 52 and the connection land 54, or Au plating is performed after Ni plating is applied as a base. Then, a conductive adhesive is applied to at least one of the reinforcing land 52 and the connecting land 54. Next, the reinforcing land 52 and the connection land 54 are arranged to face each other, and the connection layer 62 is formed and bonded by heating with a heater such as a heater chip.

  Below, the formation method of the connection part reinforcement structure which concerns on 1st Embodiment is demonstrated, referring FIG.1 and FIG.2.

  (A) First, the first substrate 10 and the second substrate 30 are prepared. Then, as shown in FIGS. 2A and 2B, the first connection terminal 22 and the second connection terminal 42 are faced to face each other.

  (B) Next, the end 34 is bent so as to hold the first substrate 10 so that the end 34 of the second substrate 30 shown in FIG. 2B reaches a part of the back surface 14 of the first substrate 10. It is done. When the end portion 34 is bent, the connection land 54 provided on the end portion 34 reaches the reinforcing land 52 provided on the back surface 14 of the first substrate 10.

  (C) As shown in FIG. 1B, the reinforcing land 52 and the connection land 54 are formed with a connection layer 62 by a bonding method such as solder bonding, ultrasonic bonding, or bonding with a conductive adhesive. Are joined. Similarly, as shown in FIG. 1B, the connection layer 60 is also formed on the first connection terminal 22 and the second connection terminal 42 by a bonding method such as solder bonding, ultrasonic bonding, or bonding with a conductive adhesive. Formed and joined.

  In the connection portion reinforcing structure according to the first embodiment, both the connection layer 60 that connects the first connection terminal 22 and the second connection terminal 42 on the surface 12 and the connection layer 62 of the connection portion reinforcement 70 are soldered. In the case of being provided by joining, the connection of the first connection terminal 22 and the second connection terminal 42 and the connection of the connection portion reinforcing portion 70 can be performed simultaneously, and it is necessary to provide a separate process for the connection of the connection portion reinforcing portion 70. Disappear.

  Moreover, in the connection part reinforcement structure which concerns on 1st Embodiment, all of the connection layer 60 which connects the 1st connection terminal 22 and the 2nd connection terminal 42 of the surface 12, and the connection layer 62 of the connection part reinforcement part 70 are both. Is provided by ultrasonic bonding, the first connection terminal 22 and the second connection terminal 42 can be connected and the connection portion reinforcing portion 70 can be connected simultaneously, and a separate process for connecting the connection portion reinforcing portion 70 is performed. There is no need to provide it.

  According to the connection portion reinforcing structure according to the first embodiment of the present invention, since the reinforcing land 52 is provided on the back surface 14 of the first substrate 10, the connection can be made without increasing the area of the first substrate 10. Since the reinforcement part 70 can be formed, connection strength can be improved.

  Moreover, according to the connection part reinforcement structure which concerns on 1st Embodiment, since the reinforcement land 52 was provided in the back surface 14 of the 1st board | substrate 10, the 1st designed on the surface 12 of the 1st board | substrate 10 was carried out. Since the wiring pattern 20 is not affected and the area can be increased, the reinforcing strength can be increased.

  Furthermore, according to the connection portion reinforcing structure according to the first embodiment, since the reinforcing land 52 is provided on the back surface 14 of the first substrate 10, the first wiring pattern 20 is narrow to provide the reinforcing land 52. The pitch never disappears.

(Second Embodiment)
As shown in FIG. 3, the connection reinforcing portion 72 of the connection portion reinforcing structure according to the second embodiment of the present invention is provided with the reinforcing land 52 and the connecting land 54 of the connection reinforcing portion 70 shown in FIG. Not different. Others are substantially the same as the connecting portion reinforcing structure shown in FIG.

  The connection reinforcing portion 72 is an adhesive such as a resin that joins the back surface 14 of the first substrate 10 and the end portion 34 of the second substrate 30. When a thermosetting resin adhesive is used for the connection reinforcing portion 72, the adhesive is filled between the back surface 14 of the first substrate 10 and the end portion 34 of the second substrate 30 and bonded by applying heat and pressure. To do. Further, the connection strength between the first substrate 10 and the second substrate 30 can be further reinforced by using an underfill resin filled between the IC chip and the substrate in the lip chip mounting as the connection reinforcing portion 72. The filling of the underfill resin can be performed by any one of a pre-coating method and a post-coating method.

  According to the connection portion reinforcement structure according to the second embodiment of the present invention, the connection strength between the first substrate 10 and the second substrate 30 can be reinforced without providing the reinforcement land 52 and the connection land 54. Therefore, the process can be shortened and the cost can be saved.

(Third embodiment)
As shown in FIG. 4, the connection reinforcing portion 76 of the connection portion reinforcing structure according to the third embodiment of the present invention includes the reinforcing land 52, the connecting land 54, and the connecting layer 62 shown in FIG. 1. Instead of the connection reinforcing portion 70 provided, a third wiring pattern (not shown) having a third connection terminal 82 provided on the back surface 14 of the first substrate 10 and an end portion 34 of the second substrate 30 are provided. A difference is that a fourth wiring pattern (not shown) having a fourth connection terminal 92 and a connection layer 64 that connects the third connection terminal 82 and the fourth connection terminal 92 are provided. Others are substantially the same as the connecting portion reinforcing structure shown in FIG.

  According to the connection portion reinforcing structure according to the third embodiment of the present invention, since the circuit pattern of the conductor is designed on the back surface 14 of the first substrate 10, the design can be performed without increasing the area of the first substrate 10. The density can be increased and the connection strength can be improved at the same time.

(Fourth embodiment)
As shown in FIG. 5, the connection portion reinforcing structure according to the fourth embodiment of the present invention is provided with a first fold line 36 and a second fold line 38 at the end portion 34, as shown in FIG. Different from the two substrates 30. Others are substantially the same as the connecting portion reinforcing structure shown in FIG.

  As shown in FIG. 6, the first fold line 36 and the second fold line 38 serve as a base point for bending the end portion 34. The distance between the first fold line 36 and the second fold line 38 depends on the thickness of the first substrate 10, and is designed so that the bent end 34 matches the first substrate 10.

  The connection land 54 is disposed so as to coincide with the position of the reinforcing land 52 provided on the back surface 14 of the first substrate 10 when the end portion 34 is bent.

  According to the connection portion reinforcing structure according to the fourth embodiment of the present invention, the connection reinforcing portion is formed even when the width of the first substrate 10 is wide and the end portion 34 cannot be bent from the side. Connection strength can be improved.

(Other embodiments)
As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques should be apparent to those skilled in the art.

  For example, the connection portion reinforcing structure in the second embodiment has been described as forming the connection reinforcing portion 72 by bending the end portion 34 of the second substrate 30 so as not to overlap as shown in FIG. As shown in FIG. 7, the end portions 34 a and 34 b may hold the entire back surface 14 of the first substrate 10. Since the end portions 34a and 34b hold the entire back surface 14 of the first substrate 10, the connection reinforcing portion 72a that joins the back surface 14 and the end portion 34a and the end portion 34a and the end portion 34b are connected. The connection strength can be improved by the connection reinforcing portion 72b to be joined.

  Moreover, it is also possible to use a connection part reinforcement structure as shown in FIG. 7 in combination with the first and third embodiments.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

Fig.1 (a) is a top view (the 1) which shows the connection part reinforcement structure which concerns on the 1st Embodiment of this invention, FIG.1 (b) is the AA direction of Fig.1 (a). It is sectional drawing seen from. Fig.2 (a) is a top view (the 2) which shows the connection part reinforcement structure which concerns on the 1st Embodiment of this invention, FIG.2 (b) is a BB direction of Fig.2 (a). It is sectional drawing seen from. It is sectional drawing which shows the connection part reinforcement structure which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the connection part reinforcement structure which concerns on the 3rd Embodiment of this invention. It is a top view which shows the connection part reinforcement structure which concerns on the 4th Embodiment of this invention. It is a perspective view which shows the connection part reinforcement structure which concerns on the 4th Embodiment of this invention. It is sectional drawing which shows the connection part reinforcement structure which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 1st board | substrate 12 ... Front surface 14 ... Back surface 20 ... 1st wiring pattern 22 ... 1st connection terminal 30 ... 2nd board | substrate 32 ... Center part 34, 34a, 34b ... End part 36 ... 1st bending line 38 ... 2nd Bending line 40 ... second wiring pattern 42 ... second connection terminal 52 ... reinforcement land 54 ... connection land 60, 62, 64 ... connection layer 70, 72, 72a, 72b, 76 ... connection reinforcement portion 82 ... third connection terminal 92 ... Fourth connection terminal

Claims (11)

A first substrate having a first wiring pattern having a first connection terminal provided on the surface;
A second substrate having a center portion provided with a second wiring pattern having a second connection terminal connected to the first connection terminal and an end portion bent to reach the back surface of the first substrate;
A connecting portion reinforcing structure comprising: a connecting reinforcing portion that connects a back surface of the first substrate and an end portion of the second substrate. The connection reinforcing portion is
A reinforcing land provided on the back surface of the first substrate;
A connection land provided at an end of the second substrate;
The connection portion reinforcing structure according to claim 1, further comprising: a connection layer that connects the reinforcement land and the connection land.   The connection portion reinforcing structure according to claim 2, wherein the connection layer is provided by solder bonding.   The connection part reinforcing structure according to claim 2, wherein the connection layer is provided by ultrasonic bonding.   The connection reinforcing structure according to claim 1, wherein the connection reinforcing portion is formed by bonding an insulating layer and a cover layer of the first substrate and the second substrate with an adhesive.   The connection reinforcement structure according to claim 1, wherein the connection reinforcement is an adhesive. The connection reinforcing portion is
A third wiring pattern provided on the back surface of the first substrate;
A fourth wiring pattern provided at an end of the second substrate;
The connection portion reinforcing structure according to claim 1, further comprising: a solder layer that connects the third wiring pattern and the fourth wiring pattern.   The connection portion reinforcing structure according to claim 1, wherein the first substrate is a rigid rigid substrate.   The connection part reinforcing structure according to claim 1, wherein the first substrate is a flexible flexible substrate. A central portion provided with a wiring pattern;
A printed wiring board comprising a foldable end portion provided with a connection reinforcing portion for reinforcing connection strength between the wiring pattern and a wiring pattern of another substrate at both ends of the central portion. A first substrate having a first wiring pattern having a first connection terminal provided on the surface, a central portion having a second wiring pattern having a second connection terminal connected to the first connection terminal, and the first substrate Providing a second substrate having an end portion reaching the back surface of
Facing the first connection terminal and the second connection terminal so as to face each other;
Bending the end so as to hold the first substrate, the end reaching the back surface of the first substrate;
Forming a connection reinforcing portion that connects a back surface of the first substrate and an end portion of the second substrate.

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