JP2006173535A - Flexible substrate and its connecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible substrate and its connecting method that can achieve high mounting quality. <P>SOLUTION: The flexible substrate 10 having a reinforcing plate 1 stuck on the back of a connection part connected to a rigid substrate is mounted at a designated position on the rigid substrate by using a component mounting machine, and heated and pressed to connect the flexible substrate 10 to the rigid substrate, and then the reinforcing plate 1 is peeled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flexible substrate for connecting to a rigid substrate on which electronic components and the like are mounted, and a method for connecting the flexible substrate.

  As electronic devices become smaller and thinner, thin and flexible flexible substrates are often connected to rigid substrates on which electronic components and the like are mounted. The connection between the rigid substrate and the flexible substrate is performed by, for example, aligning the connection land of the flexible substrate with the connection land of the rigid substrate coated with solder using an alignment jig or the like, and heating and pressurizing ( For example, see Patent Document 1.)

Japanese Patent No. 2634880

  However, in the above connection method, since the flexible substrate is flexible, the adsorptivity and the recognizability by the alignment jig or the like are not stable, and it is difficult to align with high accuracy.

  Further, since the flatness of the connection surface on which the connection land of the flexible substrate is formed is not stable, the quality when mounted is unstable.

  Furthermore, since the flexible substrate is light, positional displacement may occur due to vibration during conveyance, and the aligned flexible substrate may be lost due to wind pressure in the reflow process of heating and pressurization.

  The present invention has been proposed in view of such a conventional situation, and an object of the present invention is to provide a flexible substrate and a connection method thereof that can realize high mounting quality.

  In order to achieve the above-described object, a flexible substrate according to the present invention includes a connection portion connected to a rigid substrate, and a peelable reinforcing plate is attached to at least the back surface of the connection portion. It is characterized by that.

  Further, the flexible substrate connection method according to the present invention is a flexible substrate connection method including a connection portion connected to a rigid substrate, wherein the flexible substrate having a reinforcing plate attached to the back surface of the connection portion is a predetermined portion of the rigid substrate. The flexible board is connected to the rigid board by being mounted at the position, heated and pressed, and then the reinforcing plate is peeled off.

  In the flexible substrate according to the present invention, the flatness of the connection surface of the flexible substrate is stabilized and a certain degree of rigidity and weight are provided by attaching a peelable reinforcing plate to the back surface of the connection portion connected to the rigid substrate. Therefore, highly accurate and stable mounting can be performed using a component mounting machine.

  In addition, the flexible substrate connecting method according to the present invention includes mounting a flexible substrate having a reinforcing plate attached to the back of a connecting portion connected to a rigid substrate using a component mounting machine at a predetermined position of the rigid substrate. Highly accurate and stable connection can be realized. Moreover, after connecting a flexible board and a rigid board | substrate by heating and pressurization, a reinforcement board does not exist in a mounted product by peeling a reinforcement board, and high mounting quality can be acquired.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In this embodiment, a flexible substrate is connected by solder, thereby realizing a reduction in size and thickness of a mounting substrate.

  FIG. 1 is a cross-sectional view showing a state in which a reinforcing plate 1 for maintaining strength is attached to a connection terminal portion of a flexible substrate 10, and FIG. 2 shows a state in which the reinforcing plate 1 is attached to the entire flexible substrate 10. It is sectional drawing shown.

The reinforcing plate 1 is made of metals such as SUS (Stainless Used Steel) and aluminum, and resins such as glass fiber reinforced epoxy, polyimide, and Ultam. The reinforcing plate 1 preferably has a certain weight, for example, a density of 1 g / cm ³ or more. Thereby, the jump of the flexible substrate 10 in the reflow process can be prevented, and displacement can be prevented. Further, it is preferable that heat resistance is exhibited at a temperature at which the solder is melted, for example, a temperature of 250 ° C. or more, and the dimensional change due to temperature change and the warping behavior are stable. Thereby, the curvature of the flexible substrate 10 in a reflow process can be prevented. Furthermore, it is preferable that it has rigidity and is easy to process. Thereby, for example, as shown in FIG. 2, the entire flexible substrate 10 can be processed.

  The magnitude | size and weight of the reinforcement board 1 to stick are determined in consideration of the role as a weight. For example, when only one side of the flexible substrate 10 is soldered as shown in FIG. 1, the reinforcing plate 1 does not need to cover the entire surface of the flexible substrate 10. For example, when the reinforcing plate 1 is made of SUS (Stainless Used Steel) having a thickness of 0.5 mm, the size of the reinforcing plate 1 is not less than ½ of the length of the flexible substrate 10 or the area of the flexible substrate 10. It is preferable that it is 1/2 or more.

  By sticking such a reinforcing plate 1 to the flexible substrate 10, it is possible to maintain the flatness and strength of the flexible substrate 10 and prevent warping.

  The flexible substrate 10 includes a film-like base material 11, a wiring pattern 12, a surface protective film 13 that protects the wiring pattern 12, and a connection reinforcing plate 14 that reinforces the connection portion.

  The base material 11 has flexibility made of an insulating resin, and is formed of, for example, a material such as polyimide, polyethylene terephthalate, polyester, or polysulfone.

  The wiring pattern 12 is made of, for example, copper, aluminum, or a material obtained by plating a metal such as nickel or gold on copper or aluminum. The wiring pattern 12 is formed by, for example, laminating a metal material such as copper on a base material by a laminating method or a sputtering method, and then patterning it by a photolithography method or an etching method.

  The surface protective film 13 is made of, for example, an insulating film such as a polyimide resin or a urethane resin, and prevents the occurrence of corrosion due to the exposure of the wiring pattern 12 and the occurrence of a short circuit due to contact of a metal frame or foreign matter.

  The connection reinforcing plate 14 is bonded to the base material 11 on the back surface where the connection land is formed. The connection reinforcing plate 14 is made of polyimide or the like and maintains the flatness and strength of the connection portion where the connection land is formed.

  Here, adhesion between the reinforcing plate 1 and the flexible substrate 10 will be described. The reinforcing plate 1 is attached via an adhesive layer 17 composed of a strong adhesive layer 15 and a weak adhesive layer 16 so that it can be peeled off with a slight force after completing the connection by the reflow process. The adhesive layer 15 is disposed on the reinforcing plate side, and the weak adhesive layer 16 is disposed on the flexible substrate side.

  It is preferable that the adhesive layer 17 exhibits heat resistance at a temperature at which solder is melted, for example, a temperature of 250 ° C. or higher, and has little change in adhesiveness with respect to temperature change. Moreover, it is preferable that the thickness of this adhesion layer 17 is 150 micrometers or less. The adhesive forming the pressure-sensitive adhesive layer 17 may be liquid, tape-like, or sheet-like, and is adhered to the entire surface or a part of the reinforcing plate 1.

  Further, the adhesive surface of the strong adhesive layer 15 has an adhesive property of 1.0 N / cm or more, and the adhesive surface of the weak adhesive layer 16 has an adhesive property of 0.1 N / cm or more and 0.5 N / cm or less. It is preferable. That is, in order to peel the reinforcing plate 1 with a slight force, it is preferable that there is a difference of 0.5 N / cm or more in the adhesiveness between the adhesive surfaces of the strong adhesive layer 15 and the weak adhesive layer 16. In addition, when the stress at the time of peeling is 2.0 N / cm or more, a crack may occur in the soldered connection portion.

  By sticking the reinforcing plate 1 with such a configuration, the reinforcing plate 1 can be easily peeled after the mounting is completed. Therefore, a highly reliable connection can be realized without applying stress to the soldered connection portion and generating cracks.

  Next, a method for connecting the flexible substrate 10 will be described with reference to FIGS.

  FIG. 3 is a perspective view showing a collective substrate 30 on which a flexible substrate or the like is mounted. The collective substrate 30 is formed of an insulating base material such as a glass epoxy material or a polyimide resin, and the rigid substrates 2a and 2b and the discard substrate 3 are integrated.

  The rigid boards 2a and 2b have a wiring pattern to which a flexible board or the like is connected. This wiring pattern is formed by attaching and etching a conductive foil such as copper or aluminum on one surface of an insulating substrate. A connection land is formed at a predetermined position where the electronic component is mounted.

  The discard board 3 is disposed on a part or the whole of the rigid boards 2a and 2b, and holds the rigid boards 2a and 2b. Thereby, the curvature of the rigid board | substrates 2a and 2b produced at the time of mounting of an electrical component can be reduced.

  FIG. 4 is a perspective view showing the collective substrate 40 in which the solder 4 is applied on the rigid substrates 2a and 2b. The solder 4 is applied to connection lands formed at predetermined positions on the rigid boards 2a and 2b by, for example, solder cream printing. Although the solder 4 is applied to the rigid substrate side, the solder 4 may be applied to the flexible substrate side.

  FIG. 5 is a perspective view showing a collective substrate 50 on which the flexible substrate 10 on which the electronic component 5 and the above-described reinforcing plate 1 are attached is mounted at a predetermined position. This collective substrate 50 is mounted by mounting the electronic component 5 and the flexible substrate 10 on a predetermined position of the collective substrate 40 shown in FIG. 4 using a component mounting machine, and melting and curing the solder 4 by heating and pressing. It has been made.

  As described above, since the reinforcing plate 1 is adhered to the flexible substrate 10, it can be easily mounted using a component mounting machine. Moreover, by sticking the reinforcing plate 1, the curvature of the flexible substrate 10 can be reduced and the flatness of a connection part can be ensured. Furthermore, in the reflow process, the reinforcing plate 1 also serves as a weight for preventing jumping, and can prevent displacement. Thereby, high connection reliability can be ensured.

  Then, after heating and pressurizing, the reinforcing plate 1 adhered to the flexible substrate 10 is peeled off, and the discarded substrate 3 is cut away, whereby the mounting substrate 60 shown in FIG. 6 is completed. Therefore, the reinforcing board 1 does not exist on the mounting board 60, and the mounting board 60 having high mounting quality can be obtained.

  According to the present invention, by sticking the peelable reinforcing plate 1 to the back surface of the connection portion of the flexible substrate 10, the flatness of the connection surface on which the connection land is formed is stabilized, and a certain degree of rigidity and weight are provided. It will have. Thereby, while performing highly accurate and stable mounting using a component mounting machine, the curvature and the jump of the flexible substrate 10 in a reflow process can be prevented. Therefore, not only high mounting quality can be realized, but high-density mounting is possible, and the mounting substrate can be reduced in size and thickness.

  In the present embodiment, the flexible substrate 10 with the reinforcing plate 1 attached in advance is mounted on the rigid substrate 2 as one component. However, the flexible substrate 10 without the reinforcing plate 1 attached thereto is a component. If the mounting machine can be mounted accurately, the reinforcing board 1 may be mounted on the flexible board 10 after the flexible board 10 is mounted on the rigid board 2.

It is sectional drawing which shows the example of the flexible substrate in this Embodiment. It is sectional drawing which shows the example of the flexible substrate in this Embodiment. It is a perspective view for demonstrating the connection method of the flexible substrate in this Embodiment. It is a perspective view for demonstrating the connection method of the flexible substrate in this Embodiment. It is a perspective view for demonstrating the connection method of the flexible substrate in this Embodiment. It is a perspective view for demonstrating the connection method of the flexible substrate in this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reinforcement board, 2 Rigid board, 3 Discarded board 4 Solder, 5 Electronic component, 10 Flexible board, 11 Base material, 12 Wiring pattern, 13 Surface protective film, 14 Connection reinforcement board, 15 Strong adhesion layer, 16 Weak adhesion layer, 17 Adhesive layer

Claims (6)

In a flexible board provided with a connection part connected to a rigid board,
A flexible substrate, wherein a peelable reinforcing plate is attached to at least the back surface of the connecting portion. The reinforcing plate is attached via an adhesive layer having a strong adhesive layer on the reinforcing plate side and a weak adhesive layer on the flexible substrate side,
The flexible substrate according to claim 1, wherein a difference in adhesiveness between the surface of the strong adhesive layer and the surface of the weak adhesive layer is 0.5 N / m or more.   The flexible substrate according to claim 2, wherein the adhesive surface of the weak adhesive layer has an adhesiveness of 0.1 N / m or more and 0.5 N / m or less. 2. The flexible substrate according to claim 1, wherein the reinforcing plate has heat resistance to a temperature of 250 ° C. or more and has a density of 1 g / cm ³ or more. A connection reinforcing plate is provided on the back of the connection part,
The flexible substrate according to claim 1, wherein the reinforcing plate is attached to a region including the connection reinforcing plate. In the connecting method of the flexible substrate including the connecting portion for connecting to the rigid substrate,
A flexible board with a reinforcing plate attached to the back surface of the connecting portion is mounted on a predetermined position of the rigid board using a component mounting machine, and the flexible board is connected to the rigid board by heating and pressing, Then, the said reinforcement board is peeled, The connection method of the flexible substrate characterized by the above-mentioned.

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