JP2005183588A - CONNECTED BODY AND ITS MANUFACTURING METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joining technique that can cope with high density and reduce manufacturing cost, has good electrical continuity reliability of a joined portion, and can join joined members more firmly. To do.
A joined body 1 according to the present invention is formed by joining a pair of members to be joined 10 and 20 each having a terminal, and joining the terminals 13 and 23 of the pair of members to be joined 10 and 20 together. 30 and an insulating sealing material 40 that seals between the pair of members to be joined 10 and 20 along the outer side in the longitudinal direction of the terminals 13A and 23A at the extreme ends constituting the joint 30. It is provided.
[Selection] Figure 2

Description

  The present invention relates to a joined body in which members to be joined such as a pair of printed wiring boards having terminals are joined, and a method for manufacturing the joined body.

In portable information devices such as notebook personal computers, and electronic devices such as foldable portable telephones or portable information terminals, connection terminals for rigid wiring boards on which a central processing unit (CPU) and various electronic components are mounted And a connection terminal of a flexible printed wiring board connected to a liquid crystal display device or the like must be electrically connected. As a joining technique between the connection terminals of the wiring boards, a rigid flex structure for joining the connection terminals of the same number of wiring boards (Patent Document 1, etc.), a connector terminal of one wiring board, and a connector component of the other wiring board Connector connection (patent document 2 etc.) fitted together, solder joint (patent document 3 etc.) which joins the connection terminals of a wiring board via solder, an anisotropic conductive paste between the connection terminals of a wiring board, Techniques for joining via a film are known.
Japanese Patent Laid-Open No. 5-013958 JP-A-7-176341 JP-A-5-267811

However, the preceding joining technique has the following problems.
In the rigid flex structure, (i) the area occupied by unnecessary parts in the pattern arrangement of the connection terminals is large, and it is difficult to cope with high density and narrow pitch. (Ii) The manufacturing process is high because the joining process is complicated. (Iii) There is a problem that the number of wiring boards to be joined is limited to the same number of layers, and the degree of freedom in design is limited.
In connector connection, connector terminals and connector parts, which are separate members from the wiring board, are used, resulting in high component costs and two-dimensional or three-dimensional space for connector placement. From the point of view, it was not preferable.
In solder bonding, although bonding can be performed easily and inexpensively, there is a risk that the bonded portion may be oxidized or peeled off in the reflow process after bonding.
Joining using anisotropic conductive pastes and films requires processes such as paste printing and film sticking, so the joining process is complicated and expensive to manufacture, and electrical continuity is contained in the resin. Since it depends on the contact state of the contained conductive particles, there is a problem in the reliability of electrical conduction.

  Conventionally, since the terminal pitch of the printed wiring board is relatively wide and the contact area between the terminals can be secured to some extent, sufficient joining strength can be ensured only by joining using the preceding joining technique. However, in recent years, with the miniaturization of electronic devices, the demand for narrowing the printed wiring board has become severe, and in the future, the reduction of the contact area between the terminals due to the narrowing of the pitch will lead to a decrease in bonding strength, There is a possibility that the bonded interface of the printed wiring board bonded due to external stress or the like is peeled off.

  The present invention has been made in view of the above circumstances, and can cope with higher density, narrower pitch, thinner thickness, smaller size, and reduced manufacturing cost, and the degree of freedom in design is limited. To provide a joining technique that can join members to be joined more firmly without causing fear of oxidation, peeling, etc. of joining portions, having excellent reliability of electrical continuity at the joining portions. With the goal.

The inventor has intensively studied to solve the above-mentioned problems, and invented the following joined body and a manufacturing method thereof.
The joined body of the present invention is a joined body in which a pair of members to be joined each having a terminal is joined. The joined body includes a joined portion in which the terminals of the pair of joined members are joined to each other. An insulating sealing material for sealing between the pair of members to be joined is provided along the outer surface in the longitudinal direction of the terminal at the outermost portion.
According to the joined body of the present invention, since a configuration in which the terminals are directly joined without using solder or the like is employed, a joined body having superior heat resistance compared to what is joined through solder or the like is provided. Can do. Therefore, according to the technique of the present invention, it is easy to cope with high density, narrow pitch, thin thickness, and downsizing, and the degree of freedom in design is not limited. In addition, since different types of substances such as solder and anisotropic conductive materials are not interposed at the bonding interface, there is no fear of the terminal bonding interface being oxidized or peeled off, and the bonded body has excellent electrical continuity reliability at the bonded portion. Is obtained.

  Furthermore, since the joined body of the present invention is configured to provide a sealing material that seals between the pair of members to be joined along the outer surface of the terminal at the outermost end constituting the joined portion, the joined portion is sealed. It is protected from external stress by the stopper, and the pair of members to be joined are joined by the sealing material in addition to the joining of the terminals. Will be greatly improved.

  In the joined body of the present invention, it is preferable that a gap is formed at each terminal joint interface. As a result, the bonding strength can be maintained and the durability can be improved.

It is preferable that the sealing material is provided in contact with the terminal at the outermost end constituting the joining portion.
As the sealing material, a material made of any one of a thermosetting resin, a photocurable resin, and a thermoplastic resin is suitable. By using such a sealing resin, the sealing resin can be applied and then cured to easily form a sealing material.

The method for manufacturing a joined body of the present invention includes a terminal joining step of ultrasonically joining terminals of a pair of members to be joined having terminals, and preparing a joined body having a joined portion in which the terminals are joined to each other; A sealing material application step of applying an insulating sealing material for sealing between the pair of members to be joined along the outer side surface in the longitudinal direction of the terminal at the endmost part constituting the joint part. Features.
According to the manufacturing method of the present invention, the above-mentioned joined body of the present invention can be easily manufactured. In particular, in the present invention, since the sealing material is provided along the outer surface of the connection terminal at the outermost end constituting the joining portion, the sealing material can be easily formed after joining the connection terminals. This is preferable.

  According to the joined body and the manufacturing method thereof of the present invention, it is possible to cope with high density, narrow pitch, thinning, and downsizing, and to reduce the manufacturing cost, which may limit the degree of freedom in design. In addition, it is possible to provide a joined body in which there is no fear of oxidation or peeling of the joining portion, electrical reliability of the joining portion is good, and the members to be joined can be joined more firmly.

  Next, an embodiment of a joined body according to the present invention will be described based on the drawings. 1 is a plan view, and FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG. 1. In addition, illustration of the sealing material is abbreviate | omitted in Fig.1 (a), and illustration of the upper to-be-joined member is abbreviate | omitted in FIG.1 (b). Moreover, FIG.2 (b) is an enlarged view of Fig.2 (a), and is a figure which shows a terminal-bonding interface and its vicinity. These drawings schematically show the joined body of the present embodiment, and the scale, the wiring pattern, and the like are different from the actual ones.

As shown in FIG. 1A and FIG. 2A, a joined body 1 according to this embodiment includes a flexible printed wiring board (member to be joined, hereinafter abbreviated as “FPC”) 10 and a rigid printed wiring board ( A member to be joined, hereinafter abbreviated as “RPC”) 20 is joined.
The FPC 10 includes a resin substrate 11 made of polyimide, polyethylene terephthalate, or the like, and a plurality of wirings 12 made of copper (Cu) formed in a predetermined pattern on the surface thereof, and one end of each wiring 12 is externally provided. And a connection terminal 13 for electrical connection. On the other hand, the RPC 20 includes a resin substrate 21 made of a composite material of epoxy resin and glass fiber and a plurality of wirings 22 made of copper (Cu) formed in a predetermined pattern on the surface thereof. One end of 22 is a connection terminal 23 for electrical connection with the outside. The surfaces of the non-terminal portions of the wirings 12 and 22 of these wiring boards are covered with a film-like insulating material made of polyimide or the like, or a liquid insulating material made of epoxy resin or the like (not shown).

The connection terminals 13 of the FPC 10 and the connection terminals 23 of the RPC 20 are formed at the same pitch, and the connection terminals 13 and the connection terminals 23 are ultrasonically bonded. That is, the joined body 1 includes a joined portion 30 (region shown by hatching in FIG. 1B) in which the terminals of the FPC 10 and the RPC 20 are ultrasonically joined.
In the present embodiment, as shown in FIG. 2B, a plurality of gaps 31 are scattered at the bonding interface between the connection terminals 13 and 23. The void 31 can be formed by bonding both by a specific ultrasonic bonding method. The surfaces of the connection terminals 13 and 23 are preliminarily subjected to processing necessary for bonding.

Further, in this embodiment, as shown in FIGS. 1B and 2A, between the FPC 10 / RPC 20 along the entire outer surface of the connection terminals 13A and 23A at the outermost ends constituting the joint portion 30. An insulating sealing material 40 for sealing is provided. This sealing material 40 is comprised by sealing resin which has insulation, such as a thermosetting resin, a photocurable resin, and a thermoplastic resin. By using such a sealing resin, the sealing resin 40 can be easily formed after being applied and cured. Moreover, the sealing material 40 is provided in contact with the connection terminals 13A and 23A at the outermost ends.
The joined body 1 of the present embodiment is configured as described above.

"Method of manufacturing joined body"
Next, an embodiment of a method for producing the joined body 1 will be described.
First, a Cu foil is bonded to the entire surface of the resin substrate 11 and etched to form a wiring 12 having a predetermined pattern. Next, a film-like insulating material is attached to the entire surface of the FPC 10, and an opening is formed in a portion corresponding to the connecting terminal 13 of this insulating material, thereby covering the non-terminal portion of each wiring 12 with the insulating material.
Next, gold (Au), platinum (Pt), rhodium (Rh), palladium (Pd), ruthenium (Ru), iridium (Ir) is applied to the surface of each connection terminal 13 to be subjected to ultrasonic bonding by a normal plating process. ) And the like and a corrosion-resistant metal film such as a plating film is formed.
As described above, the FPC 10 is manufactured.
The RPC 20 is manufactured in the same manner as the FPC 10.

Next, the terminals of the FPC 10 and the RPC 20 are joined by ultrasonic joining so that a gap 31 is formed at the joining interface (terminal joining step). For this joining, for example, the connection terminal 13 formed with the corrosion-resistant metal film of the FPC 10 and the connection terminal 23 formed with the corrosion-resistant metal film of the RPC 20 are overlapped, and an ultrasonic bonding machine is attached to the outer surface of one resin substrate. It can be implemented by placing a horn and applying ultrasonic vibration generated from the horn to the overlapped portion while applying a predetermined pressure to the horn.
Here, by placing a horn of an ultrasonic bonding machine on the outer surface of one resin substrate and applying a predetermined pressure to this horn, there is no direct contact with the horn against the connection terminal itself, so there is no pressure, etc. The adjustment range is expanded. Further, since the connection terminal itself is not damaged, disconnection at the time of joining and after joining can be suppressed.
The ultrasonic bonding conditions are, for example, pressure: 0.1 to 3 kgf / mm ² , bonding time: 0.1 to 1 second, and amplitude: 5 to 30 μm.

Subsequently, as shown in FIG. 3, uncured sealing resin 40 </ b> A is applied by a dispensing method in accordance with the location where the sealing material 40 is formed (sealing material application step). That is, the dispenser nozzle 50 is scanned to apply the uncured sealing resin 40A along the outer surfaces of the connection terminals 13A and 23A at the outermost ends constituting the joint portion 30. Thereafter, the uncured sealing resin 40A is cured to form the sealing material 40. Curing of the uncured sealing resin 40A can be performed by heating, light irradiation, or the like depending on the type of resin used. The “curing” includes a case where the thermoplastic resin is naturally or forcibly cooled and solidified.
As described above, the joined body 1 of the present embodiment is completed.

Ultrasonic bonding can also be performed by methods other than those described above.
For example, instead of forming a corrosion-resistant metal film on the surface of each terminal of the FPC 10 and the RPC 20 and ultrasonically bonding them, the surface of each terminal is subjected to a reduction treatment to precipitate Cu fine particles on the surface. Can be ultrasonically bonded so that the void 31 is formed at the bonding interface. Moreover, when performing ultrasonic bonding by such a method, it is preferable to perform acid cleaning prior to the reduction treatment.
The acid cleaning can be performed by immersing the connection terminal in a cleaning solution containing, for example, sulfuric acid and hydrogen peroxide. The reduction treatment is performed by, for example, immersing the connection terminal in a treatment solution containing hydrazine and NaBH ₄ or a treatment solution containing formaldehyde, alkylamine, dimethylamine borane, borohydride, phosphinic acid, sodium phosphinate, or the like. Can be implemented.

According to the joined body and the manufacturing method of the present embodiment, the connection terminal 13 of the FPC 10 and the connection terminal 23 of the RPC 20 are directly joined by ultrasonic waves, so that the heat resistance is higher than that obtained by joining via solder or the like. It is possible to provide the bonded body 1 having excellent properties.
Furthermore, in the present invention, the bonded body 1 having excellent durability can be obtained. Conventionally, even when terminals are joined by an ultrasonic joining method, a practical joining strength has been obtained. However, when a severe durability test such as a vibration test is performed, the joining strength may be lowered. . However, in this embodiment, by providing the gap 31 at the bonding interface during ultrasonic bonding, the bonding strength is maintained and the durability is improved.
The reason is not necessarily clear, but in conventional ultrasonic bonding, since the bonding interface is continuously connected, if a crack occurs even at one location in the bonding interface, the crack propagates easily from there, so the bonding strength On the other hand, in this embodiment, even if a crack occurs at the joint interface, it is presumed that the gap 31 formed at the joint interface hinders its propagation.
That is, in this embodiment, the bonded body 1 having a high bonding strength at the bonding interface and having a long life can be obtained. Therefore, it becomes easy to cope with high density, narrow pitch, thin thickness, and downsizing, and the degree of freedom in design is not limited.

  In addition, since different types of substances such as solder and anisotropic conductive materials are not interposed at the bonding interface, there is no fear of the terminal bonding interface being oxidized or peeled off, and the bonded body has excellent electrical continuity reliability at the bonded portion. 1 is obtained. In addition, since the connection terminals can be directly joined, the joining process can be simplified and the cost can be reduced.

Furthermore, the joined body 1 of the present embodiment is configured to provide the sealing material 40 that seals between the FPC 10 / RPC 20 along the outer surfaces of the connecting terminals 13A and 23A at the outermost ends constituting the joining portion 30. Therefore, the joint portion 30 is protected from external stress by the sealing material 40, and the FPC 10 and the RPC 20 are joined by the sealing material 40 in addition to the joining of the terminals, so that a large joining area can be secured. Compared to the conventional case, the bonding strength is greatly improved.
Moreover, in this embodiment, since it was set as the structure which provides the sealing material 40 along the outer surface of the connection terminals 13A and 23A of the endmost part which comprises the junction part 30, the connection terminals of FPC10 / RPC20 were joined. Thereafter, the sealing material 40 can be easily formed, which is preferable.

In the present embodiment, the sealing material 40 is provided along the connection terminals 13A and 23A at both ends constituting the joint portion 30, but may be provided only along the connection terminal at one end. Moreover, although it was set as the structure which provides the sealing material 40 along the whole connection terminal 13A, 23A, you may provide the sealing material 40 along only a part of these connection terminals, or along these connection terminals. You may intermittently divide and provide in several places. Even with this configuration, the same effects as in the present embodiment can be obtained. However, the effect of improving the bonding strength increases as the formation region of the sealing material 40 increases.
In the present embodiment, the sealing material 40 is provided in contact with the connection terminals 13A and 23A. However, the sealing material 40 may be disposed away from these connection terminals. Even with this configuration, the same effects as in the present embodiment can be obtained.

  In the present embodiment, only the example in which the present invention is applied to the FPC / RPC joined body has been described. However, the present invention is not limited to any structure as long as a pair of members to be joined having terminals are joined. It can also be applied to the body.

  The present invention relates to a joined body of electronic components mounted on an electronic device such as a portable information device and a portable telephone, specifically an FPC / FPC joined body, an RPC / FPC joined body, a flexible flat cable / FPC joined body, It can be suitably used for a membrane / FPC assembly, a tape carrier package / FPC assembly, a tape carrier package / RPC assembly, and the like.

It is a top view which shows one Embodiment of the conjugate | zygote of this invention. It is A-A 'sectional drawing of FIG. It is a figure which shows one Embodiment of the manufacturing method of the conjugate | zygote of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bonded body, 10 ... Flexible printed wiring board (member to be joined), 20 ... Rigid printed wiring board (member to be joined), 11, 21 ... Resin substrate, 12, 22 ... Wiring, 13, 23 ... Connection terminal, 13A , 23A ... the connection terminal at the end, 30 ... the joint, 31 ... the gap, 40 ... the sealing material.

Claims (5)

In a joined body formed by joining a pair of members to be joined having terminals,
While comprising a joint where the terminals of the pair of members to be joined are joined together,
A joined body comprising an insulating sealing material that seals between the pair of members to be joined along an outer surface in the longitudinal direction of the terminal at the endmost part constituting the joint.   The joined body according to claim 1, wherein a gap is formed at each terminal joint interface.   The said sealing material is provided in contact with the terminal of the outermost part which comprises the said junction part, The joined body of Claim 1 or 2 characterized by the above-mentioned.   The said sealing material consists of either thermosetting resin, photocurable resin, or thermoplastic resin, The joined body in any one of Claims 1-3 characterized by the above-mentioned. A terminal joining step of ultrasonically joining terminals of a pair of members to be joined having terminals, and preparing a joined body having a joined portion in which the terminals are joined;
A sealing material application step of applying an insulating sealing material for sealing between the pair of members to be joined along the outer side surface in the longitudinal direction of the terminal at the endmost part constituting the joint portion; The manufacturing method of the joined body characterized by these.

Images