JPH05283825A - Printed-circuit board with identification mark - Google Patents

Abstract

PURPOSE:To provide a printed-circuit board with identification marks whose image can be precisely recognized in an automatic parts-mounting system so as to prevent the decrease of efficiency in the production line. CONSTITUTION:Metal film (e.g., copper) on an insulating substrate 1 is etched according to a conductor pattern 2 to form identification marks 3. Relatively light colored, transparent resist 10 of uniform thickness is applied to over the whole surface of the substrate, except the areas 9 for pads reserved for contact with leads of a component to be mounted. Then, the areas 9 of the conductor pattern are coated with solder 8 by a solder leveling technique.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board provided with a recognition mark which serves as a mark when a device for automatically mounting chip parts or the like is arranged on a conductive pattern.

[0002]

2. Description of the Related Art As is well known, surface mounting technology for electronic parts is widely used in order to realize miniaturization of electronic equipment, and mass production and labor saving have been achieved by the advent of automatic parts mounting devices. is there. Surface mount parts (chip parts)
With the progress of miniaturization, more accurate automatic component mounting devices have been put to practical use. For example, a large number of lead terminals extending from all four sides of a mold have a quad flat pa
ckage) components, the distance between adjacent lead terminals is extremely narrow, and the lead terminals themselves are also extremely thin. Therefore, as shown in FIG. Using the printed circuit board 4 provided with the printed circuit board 3, the positional relationship between the recognition mark 3 and the conductive pattern 2 of each component is programmed in the automatic component mounting device in advance, and the component 5 is mounted as shown in FIG. The image pickup unit 6 provided right above the substrate 4 captures the image as an image, and the control unit 7 performs image processing to correct the position to improve the mounting accuracy.

The recognition mark 3 may be formed by etching the metal film attached to the surface of the insulating substrate together with other conductive patterns 2 using the same mask in the manufacturing process of the printed circuit board 4. Further, it is common to form a solder layer on the surface by a solder leveler method in order to prevent corrosion of the metal film surface similarly to the pad portion of the conductive pattern 2.

However, the recognition mark 3 obtained by performing the solder leveler method in which the printed circuit board is dipped in the solder bath and the solder layer is formed only on the exposed portion of the metal film without applying the resist film is shown in FIG. As shown in the figure, the solder layer 8 on the surface is likely to have irregularities, and when the image pickup section 6 captures this as an image, the original recognition mark has a shape indicated by a dotted line as shown in FIG. The irregularity of light on the surface of the solder layer 8 causes a part of the light to be imaged as a shadow, so that the control unit 7 cannot determine that it is the recognition mark 3 and determines that it is a defective product. There is a drawback in that wasteful operations such as stopping the process or discharging the printed circuit board 4 are performed, which lowers the efficiency of the production line and increases the cost. In order to solve this, if the technique of forming a plating layer by plating a metal such as solder, copper or gold instead of forming the solder layer by the solder leveler method, the unevenness on the surface of the recognition mark 3 can be removed. However, it has a drawback that the cost is higher than that of the solder leveler method and that the solder plating layer is melted by reflow heating after mounting the parts, and thus wrinkles are generated in the resist film.

Further, when the insulating substrate 1 is light transmissive like glass epoxy, the image pickup section 6 is operated by the image pickup section 6 due to the transmission of light rays from the back surface of the substrate or the diffusion phenomenon of light within the substrate. The recognition mark 3 is difficult to be captured as an image, and the control unit 7 often fails to determine that the recognition mark 3 is the recognition mark 3, which is similar to the above-described drawback.

[0006]

An object of the present invention is to eliminate the drawbacks of the conventional printed circuit board with the recognition mark as described above, and to improve the accuracy of the judgment of the recognition mark by the image in the automatic component mounting apparatus, An object of the present invention is to provide a structure of a printed circuit board with an identification mark, which prevents a reduction in line efficiency.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, a printed circuit board with a recognition mark according to the present invention has a recognition mark provided on the insulating substrate as a reference of the position of a conductive pattern arranged on the insulating substrate. A conductive thin film formed on the upper surface of which is covered with a transparent thin film, and has a larger area than the recognition mark at the same position as the recognition mark on the back surface of the insulating substrate or the intermediate layer. An opaque film may be provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings showing the embodiments. FIG. 1 is a cross-sectional view showing the configuration of an embodiment of a printed circuit board with an identification mark according to the present invention, in which a metal film (for example, copper foil) on an insulating substrate 1 is etched in the same manner as other conductive patterns 2. A recognition mark 3 is formed by the method described above, and a relatively pale transparent resist thin film 10 having a relatively light color is evenly formed on the entire substrate surface excluding a pad portion 9 which becomes a contact point with a lead terminal of a component to be mounted in the next step. The solder layer 8 is applied thinly, and then the solder leveler method is performed as the next step to form the solder layer 8 only on the pad portion 9 of the conductive pattern 2. With the above-described structure, the recognition mark 3 on the printed board 4 has its surface covered with the transparent resist thin film 10. Therefore, even if the solder leveler method is applied, the solder layer is likely to have irregularities. It is possible to hold the flat surface of the copper foil without forming a groove, and when this substrate is loaded in the automatic component mounting device and the recognition mark 3 is determined by the imaging unit and the control unit, the surface of the recognition mark 3 is Since diffuse reflection of light does not occur, the judgment rate is significantly improved.

2 (a) and 2 (b) are sectional views showing the construction of another embodiment of the printed circuit board with the recognition mark according to the present invention. FIG. 2 (a) shows the passage of light. The double-sided substrate 11 made of easy-to-use glass epoxy is provided with the recognition mark 3 in which a metal film on one main surface of the double-sided substrate 11 is formed in a predetermined shape, and the surface is covered with the transparent resist thin film 10. A shield film 12 having a larger area than the recognition mark 3 formed by etching a metal film is provided at the same position as the recognition mark 3 on the other main surface of the substrate 11, that is, directly behind the recognition mark 3. FIG. 2B shows an example in which the shielding film 12 is formed in the intermediate layer of the multilayer substrate 13 similarly made of glass epoxy. The shielding film 12 shields light incident from the surface of the substrate 11 or 13 that easily transmits light on the side opposite to the recognition mark 3, and at the same time, the shielding film 12 and the substrate 11
Alternatively, the surface to be adhered with 13 is generally roughened in order to enhance mutual adhesion, so that light is absorbed at the surface with the shielding film 12 to prevent diffusion of light inside the substrate. This makes it easier for the image pickup unit 6 of the automatic component mounting apparatus to capture the recognition mark 3 as an image, and allows the control unit 7 to make a reliable determination.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and instead of the transparent resist thin film, another transparent thin film made of a material having relatively high heat resistance may be used, and it is not always necessary. It need not be the same as the resist.
Further, it goes without saying that if the shielding film is made of not only a metal film but also an opaque film, the same effect is obtained. Further, in the present invention, “transparent” means that the imaging unit and the control unit of the automatic component mounting apparatus can distinguish the recognition mark as an image through the transparent thin film on the recognition mark, and it is not always colorless and transparent. It doesn't have to be.

[0011]

Since the present invention is configured as described above, erroneous determination of a recognition mark on a printed circuit board in an automatic component mounting device can be performed without making a special change in the manufacturing process of the printed circuit board. It is possible to prevent the efficiency of the production line from being lowered, and it is possible to achieve a significant effect in realizing cost reduction.

[0012]

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of an embodiment of a printed circuit board with an identification mark according to the present invention.

2A and 2B are cross-sectional views showing the configuration of another embodiment of the printed circuit board with the recognition mark according to the present invention.

FIG. 3 is a plan view showing the configuration of a conventional printed circuit board with an identification mark.

FIG. 4 is a block diagram showing a configuration of an image processing unit of the automatic component mounting device.

5A and 5B are views for explaining a defect of a conventional printed circuit board with an identification mark.

[Explanation of symbols]

 1 ... Insulating substrate 2 ... Conductor pattern 3 ... Recognition mark 4 ... Printed circuit board 10 ... Transparent resist thin film 12 ... Shielding film

Claims (4)

[Claims] 1. A printed circuit board provided with a recognition mark as a mark of a conductive pattern arranged on an insulating substrate, wherein the recognition mark is a conductive thin film formed on the insulating substrate, the surface of which is transparent. A printed circuit board with an identification mark, characterized by being covered with a thin film. 2. The printed circuit board with a recognition mark according to claim 1, wherein the recognition mark is formed of the same conductive material as the conductive pattern at the same time. 3. The identification mark according to claim 1 or 2, wherein the transparent thin film is a resist thin film applied to protect the conductive patterns or prevent short circuits between the patterns. Printed board. 4. An opaque film having an area larger than that of the recognition mark is provided on the back surface of the insulating substrate or on an intermediate layer at substantially the same position as the recognition mark. Printed circuit board with recognition mark.