JP2001007460A - Recognition mark structure for flexible substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the recognizing accuracy of recognition marks by means of an image pickup camera. SOLUTION: In a recognition mark structure for a flexible substrate 1 formed by laminating reinforcing plates 2 to the substrate 1, recognition marks 10-12 are formed at prescribed positions on the substrate 1 and, at the same time, scraped-through sections 13-15 having larger sizes than that of the marks 10-12 are provided at the portions of the reinforcing plates 2 corresponding to the marks 10-12. Consequently, large differences can be produced in the contracts between the marks 10-12 and their backgrounds, and the marks 10-12 can be recognized surely and stably even when the marks 10-12 are recognized by taking the pictures of the marks 10-12 with a black-and-white camera. Therefore, the accuracy of the automatic recognition in a parts mounting process can be improved remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible substrate having a back surface bonded with a reinforcing plate, and more particularly to a flexible substrate recognition mark structure.

[0002]

2. Description of the Related Art Conventionally, glass epoxy substrates (FR-
4) When mounting electronic components such as a semiconductor element such as a bare chip on a circuit board such as a flexible substrate (FPC), or performing wire bonding to the pads,
It is important to align the circuit board with the electronic component. Since it is necessary to accurately recognize the position of the circuit board for alignment, automatic recognition of the circuit board exclusively using image processing technology has been performed in recent high-density mounting.

In the automatic recognition of a circuit board by image processing technology, a recognition mark is appropriately provided in a peripheral portion of the circuit board or in the vicinity of a mounting position of an electronic component, and these recognition marks are electrically scanned by an image recognition device such as an image pickup camera. , And calculates the tilt error when positioning the circuit board from the position data, and corrects the tilt error of the board based on the position data based on the recognition mark near the component mounting position while correcting various electronic errors. Components are mounted and wire-bonded.

The image of the recognition mark picked up by the image pickup camera is converted into pixels by the image recognition device through binarization processing or digital gradation processing, and the difference in brightness between the pixels (that is, the recognition mark). By discriminating the contrast difference between the mark and the film material serving as the background, the target recognition mark is electrically recognized.

[0005] As an imaging camera used in the image recognition apparatus, there is a black-and-white camera or a color camera, but a black-and-white camera which is relatively inexpensive compared with the price of the apparatus is usually used.

[0006]

Generally, copper foil lands formed together with wiring patterns of a circuit board are used as the above-mentioned recognition marks, and the surfaces thereof are coated with gold plating similarly to other wiring patterns. It has been given.

Here, among the circuit boards, the glass epoxy board has a surface whose solder resist (insulating coating) is green and has a large contrast difference from the orange color of the gold plating pattern. Is relatively easy to recognize.

On the other hand, in the case of a flexible substrate,
The color of the cover film on the surface corresponding to the material of the base film (polyimide) and the resist, which is the base material, is orange, and this is similar to the color of the gold plating pattern of the recognition mark. Since an aluminum reinforcing plate is attached to the part to be mounted for reinforcement during component mounting, this reinforcing plate prevents light transmission in the background part of the recognition mark, and as a result, The contrast difference was made extremely shallow, and high recognition accuracy could not be obtained by imaging with a monochrome camera. Further, in some cases, recognition becomes impossible. In such a case, the component mounting line is stopped as a device error, so that the working efficiency is extremely poor.

As a means of increasing the recognition rate of the recognition mark, there is a method of oxidizing the surface of the copper foil land, which is the recognition mark, without applying gold plating, and imaging the blackened recognition mark. Although the contrast with the background can be obtained by the blackening, the blackening varies depending on the degree of oxidation, so that there are cases where recognition is possible and cases where recognition is not possible, which lacks stability and reliability.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. A hollow portion is provided in a portion of a reinforcing plate corresponding to a recognition mark to allow illumination for imaging to pass therethrough, and the recognition mark and the corresponding mark are provided. It is an object of the present invention to provide a recognition mark structure of a flexible substrate that increases the accuracy of recognition of a recognition mark by an imaging camera by increasing a contrast difference from a background portion.

[0011]

That is, in the present invention,
In a recognition mark structure of a flexible substrate in which a reinforcing plate is attached to the back surface, a recognition mark is provided at a predetermined position of the flexible substrate, and a hollow portion larger than the recognition mark is provided at a portion corresponding to the recognition mark of the reinforcing plate. It is characterized by having been provided.

In the above configuration, when the image of the recognition mark on the flexible board is picked up by the imaging camera, the light irradiated on the recognition mark is reflected, but in the background, the light transmitted through the film material of the flexible board is hollowed out. , A large difference occurs in the contrast between the recognition mark and the background. For this reason, even if a black-and-white camera is used, the recognition mark can be reliably recognized.
The position of the substrate can be accurately recognized by the image recognition device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a recognition mark according to the present invention will be described below with reference to FIGS.

FIG. 1 is a view showing a circuit board to which the present invention is applied, and FIG. 2 is a view showing a main part of an AA section thereof.

In FIG. 1, reference numeral 1 denotes a flexible substrate (FP).
The circuit board according to C) is shown, and reference numeral 2 is a reinforcing plate bonded to the back surface of the component mounting area of the circuit board 1. The reinforcing plate 2 is made of, for example, aluminum having a thickness of about 2 mm, and also serves as a heat radiating plate for reinforcing the substrate when mounting components and absorbing heat generated by the mounted components.

As shown in FIG. 2, the circuit board 1 comprises a base film 3 forming a base portion, a copper foil pattern 5 for wiring formed on the surface of the base film 3, and a copper foil pattern 5 3 by cover film 4 for insulation
It has a layered structure, each of which is bonded by an adhesive.

Reference numerals 6 to 9 in FIG. 1 denote openings formed by hollowing out the flexible substrate 1, in which a part of the reinforcing plate 2 adhered to the back surface is exposed. The openings 6 to 9 have a rectangular shape in which a semiconductor element such as a bare chip can be accommodated, and pads P (FPC pads) are formed in a line at upper and lower portions. From 6 to 9, connection is made by wire bonding to pads of the semiconductor element directly bonded and mounted on the exposed surface of the reinforcing plate 2. Code 10-12
Are recognition marks for positioning provided in the vicinity corresponding to each of these openings 6 to 9 (that is, the semiconductor elements to be mounted). These recognition marks 10 to 12 are copper foil lands which are formed simultaneously with the wiring pattern (5) and the like of the circuit board 1 omitted in FIG. 1, and the surface thereof is plated with gold similarly to the wiring pattern (5) and the like. It has been given.

In the present embodiment, a round hole-shaped hollow portion 1 having a size larger than that of the recognition marks 10 to 12 is provided at a portion on the reinforcing plate 2 side corresponding to the recognition marks 10 to 12.
3 to 15 are provided. The hollow portions 13 to 15
The recognition marks 10 to 12 are formed on the inside in a size that can be accommodated with some allowance. In this embodiment, when the hole diameter of the recognition marks 10 to 12 is about 0.5Φ, the circuit board The hole diameter is formed to be about 2Φ in consideration of a bonding error of the reinforcing plate 2 to 1.

Lands 17 are provided at the lower left and right ends of the circuit board 1 outside the component mounting area (outside the reinforcing plate 2).
Reference numeral 18 denotes a recognition mark for detecting a tilt error at the time of positioning the substrate, which is formed by plating a copper foil land with gold similarly to the recognition marks 10 to 12. Reference numeral 16 denotes an input / output connector terminal of the circuit board 1.

In the above configuration, when the recognition marks 10 to 12 are picked up by the image pickup camera, the light L applied to the recognition marks 10 to 12 is reflected, but the light L transmitted through the film material is hollowed out in the background. Since the light passes through the penetrating portions 13 to 15, there is a large difference in contrast with the recognition marks 10 to 12, and the recognition marks 10 to 12 can be reliably recognized even when a monochrome camera is used. As a result, accurate and accurate recognition of the component mounting position on the circuit board 1 can be performed, so that fine pitch semiconductor elements can be mounted and wire bonding can be performed with remarkable accuracy.

Further, according to the present configuration, since the recognition mark as in the prior art can be used as it is without changing it, it does not cause a cost increase when applying the present invention.

In the embodiment described above, the material of the reinforcing plate 2 is made of aluminum. However, the present invention is not limited to this, and it is of course possible to use a glass resin material such as FRP. In addition, the hollow portions 13 to 15 are individually round holes, but are not limited to these shapes. In short, the hollow portions 13 to 15 have a shape that allows irradiation light at the time of imaging to pass around each of the recognition marks 10 to 12. I just want it.

[0023]

As described above, according to the present invention, in a recognition mark structure for a flexible substrate formed by bonding a reinforcing plate, a recognition mark is formed at a predetermined position on the flexible substrate and the reinforcing plate is formed. Since a hollow portion larger than the recognition mark is provided in the portion corresponding to the recognition mark, the contrast difference between the recognition mark and the background portion can be increased, so that the recognition mark can be reliably formed even when imaged by a monochrome camera. In addition, it can be recognized stably. As a result, the accuracy of the component mounting process by automatic recognition can be significantly improved, and this is extremely effective for component mounting at a fine pitch and high-density mounting of a flexible substrate accompanied by wire bonding.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit board to which the present invention is applied.

FIG. 2 is a diagram showing a main part of an AA cross section in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible board (circuit board) 2 Reinforcement board (aluminum board) 10-12 Recognition mark 13-15 Hollow-out part

Claims (1)

[Claims] 1. A recognition mark structure for a flexible substrate comprising a reinforcing plate bonded to a back surface thereof, wherein a recognition mark is provided at a predetermined position on the flexible substrate, and the recognition mark is provided on a portion of the reinforcing plate corresponding to the recognition mark. A recognition mark structure for a flexible substrate, wherein a larger hollow portion is provided.