JP2006228988A - Flexible substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible substrate for achieving highly reliable connection even when an area of the connecting land is reduced. <P>SOLUTION: Connecting lands 16 which are electrically connected with a rigid substrate are allocated in the staggered shape, and a reinforcing land 17 is allocated to an edge of such lattice in order to reinforce the connecting lands 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flexible substrate connected to a rigid substrate on which electronic components and the like are mounted.

  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

  In the case of the soldering connection as described above, when the area of the connection land is reduced, the connection strength is weakened. For this reason, cracks occur in the soldered part in the connection process such as the insertion work into the connector, resulting in poor connection. In addition, even after the connection is completed, continuous stress is generated in the soldered portion due to long-term use, resulting in a connection failure.

  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 capable of realizing a highly reliable connection even if the area of the connection land is reduced. .

  In order to achieve the above-described object, a flexible substrate according to the present invention is a flexible substrate connected to a rigid substrate, wherein the flexible substrate is connected to the connection portion having a connection land electrically connected to the rigid substrate, and to the connection portion. A cable portion having a wiring, wherein the connection land is arranged in a staggered pattern, and a reinforcing land for reinforcing the connection land is arranged at an end of the connection land. .

  The flexible substrate according to the present invention can realize a highly reliable connection even if the area of the connection land is reduced by arranging the reinforcing land at the end of the connection part. Therefore, the connection lands can be arranged with high density.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a flexible substrate. 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 reinforcing plate 14 that reinforces the connection portion on which the connection land is formed.

  The base material 11 is made of a flexible insulating resin, and is made 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 reinforcing plate 14 is bonded to the base material 11 on the back surface on which the connection lands are formed. For the reinforcing plate 14, SUS (Stainless Used Steel), aluminum, glass epoxy resin, or the like is used. As a result, the strength of the connection portion having the connection lands is improved, and stress is evenly applied to each connection land, so that stress is not concentrated. Therefore, it is possible to prevent the occurrence of cracks in the soldered portion after the solder connection to the rigid substrate. Further, by preventing the generation of cracks, the area of the connection land 16 can be reduced and the connection lands 16 can be arranged at high density.

Next, an example is given and demonstrated about the connection part of the flexible substrate 10. FIG. FIG. 2 is a diagram illustrating a first example of the connection unit. A plurality of connection lands 16 are formed in the connection portion 15 corresponding to each connection land of the rigid board. For example, as shown in FIG. 2, the connection lands 16 are arranged in a three-row staggered pattern, and are arranged at intervals of 0.95 mm on a straight line in each row. That is, the connection lands 16 are arranged at intervals of 0.85mm from example 16A ₁ is 0.95mm and the oblique direction, for example from 16A ₁ 16A in _two directions that is the row direction 16B in _one direction. That is, the odd-numbered connection lands and the even-numbered connection lands are arranged so as to be shifted by a half of the connection land interval. The land width W is formed to be 0.35 mm to 0.45 mm. With such a connection land arrangement, a high-density connection portion 15 is realized.

  Reinforcing lands 17 are formed at both ends of the connecting portion 15. The reinforcing land 17 does not form a circuit, but increases the strength against peeling off of the connecting land after being soldered to the rigid board. Thereby, the soldering part of the connection land 16 can ensure high connection reliability.

  FIG. 3 is a diagram illustrating a second example of the connection unit. As in the first example, the connection lands 16 are formed in the connection portion 25 in a three-row staggered pattern. Further, in this example, the reinforcing lands 18 are arranged so that the connecting lands 16 arranged in a staggered pattern increase in the row direction, and the reinforcing lands 18 are formed in the same shape as the connecting lands 16. Specifically, the reinforcing lands 18 for 2 rows and 3 columns are formed at both ends of the houndstooth-shaped connecting land group, respectively. In this way, by forming the reinforcing land 18 so as to increase the connecting land 16 in the row direction, the connecting portion 25 can be easily reinforced without the need to form the reinforcing land 18 in a separate process.

  FIG. 4 is a diagram illustrating a third example of the connection unit. The connection portion 35 is the same as that of the second example, but a notch 19 is provided in the cable portion near the connection portion 35. The notch 19 has a shape for relieving stress concentration on the connection land portion corresponding to the end of the connection land group. Since the optimal shape of the notch 19 varies depending on the shape of the flexible substrate 10 and how stress is generated, it is preferable that the notch 19 be determined by advance examination by simulation, reliability evaluation with an actual machine, or the like. By providing this notch 19, the peeling force applied from the cable portion to the connection portion can be dispersed.

  Further, it is preferable that a dummy pattern 20 that does not form a circuit is formed on the outer periphery of the notch 19. This dummy pattern 20 has a certain degree of strength, and its width is preferably 0.5 mm or more. Thereby, it is possible to prevent the cable portion of the flexible substrate 10 from being torn by applying a peeling force to the notch 19.

  FIG. 5 is a diagram illustrating a fourth example of the connection unit. The connecting portion 45 is formed by combining the reinforcing lands 18 in the second example and the third example into one to form the reinforcing land 21 having a large area. For example, six reinforcing lands 18 shown in the second example and the third example are integrated into two rows and six to form one reinforcing land 19. Thus, by increasing the area of the reinforcing land, the peel strength can be greatly improved.

  In the above example, lands and notches for reinforcement are formed at both ends of the connection land group. However, stress may be analyzed and formed only on one side.

  Thus, by connecting the reinforcing plate, forming the reinforcing land, forming the notch, etc., it is possible to improve the connection reliability of the soldered portion when the rigid board is soldered. For this reason, the area of 16 of the connection lands can be reduced and the connection lands can be arranged with high density.

It is sectional drawing which shows the example of the flexible substrate in this Embodiment. It is a top view which shows the 1st example of a connection part. It is a top view which shows the 2nd example of a connection part. It is a top view which shows the 3rd example of a connection part. It is a top view which shows the 4th example of a connection part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flexible substrate, 11 Base material, 12 Wiring pattern, 13 Surface protective film, 14 Reinforcement board, 15 Connection part, 16 Connection land, 17 Reinforcement land

Claims (6)

In flexible boards connected to rigid boards,
A connection portion having a connection land electrically connected to the rigid board;
A cable portion having wiring connected to the connection portion,
The flexible printed circuit board, wherein the connection lands are arranged in a staggered pattern at the connection portion, and reinforcing lands that reinforce the connection lands are arranged at end portions thereof.   2. The flexible substrate according to claim 1, wherein the reinforcing lands are arranged such that the connecting lands arranged in a staggered pattern increase in a row direction.   2. The flexible substrate according to claim 1, wherein the reinforcing lands are obtained by collecting lands increased in a row direction in the staggered pattern.   The flexible substrate according to claim 1, wherein a notch is provided in the vicinity of the connection portion of the cable portion.   The flexible substrate according to claim 4, wherein a dummy pattern is formed on an outer periphery of the notch. 2. The flexible substrate according to claim 1, wherein a reinforcing plate made of at least one of SUS, aluminum, and glass epoxy resin is bonded to the back surface of the connection portion.

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