JPS61212088A - Defective display for film circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for indicating a failure on a decircuited board such as a hybrid integrated circuit.

[Description of Prior Art] In an integrated circuit, in order to adjust the resistance value of a film resistor formed on an insulating substrate using thin film or thick film technology to a specified value,
Laser trimming is used. This corrects the resistance value by making a cut in the membrane resistor with a laser, and the resistance value increases according to the cut. In such laser trimming, the resistance value after trimming may be too high or too low than the specified value due to, for example, misalignment of the resistor printed pattern. In such a case, it is considered as a trimming failure and shown in Fig. 3 or 4.
As shown in the figure, defective marks were formed and displayed on the patterned surface of the decircuited board using a laser, and the board was discarded.

FIGS. 3 and 4 each show a conventional example of defect display. FIG. 3 shows a case where a defective mark F is formed and displayed using a laser on the pattern forming surface 2 of the decircuit board 1, and the defective mark F is formed and displayed in a large size on the entire surface of the pattern forming surface 2. FIG. 4 shows a case where a defective mark F is formed and displayed using a laser on one of the lands 4a to 4C to which a transistor 3 is connected, for example, on the pattern forming surface 2 of the decircuit board 1.

By the way, such defects naturally include cases where the resistance value is insufficient due to too much laser cutting. In such a case, it is possible to adjust the resistance value of the membrane resistor to a specified value by cutting further. However, with conventional display methods, even in the case of such correctable defects, the products have no choice but to be discarded. That is, according to the method shown in FIG. 3, the circuit pattern is destroyed, and according to the method shown in FIG. This is because the wire bonding properties are significantly deteriorated, making the electrical connection of transistors etc. uncertain, and the reliability of the circuit extremely reduced.

[Object of the Invention] The present invention has been made based on the above-mentioned viewpoint, and an object of the present invention is to provide a defect display method capable of relieving a correctable defect.

[Means for Achieving the Object] In the present invention, in a method of forming and displaying a defective mark on a pattern forming surface of a g circuit board using a laser when the resistance value after laser trimming does not match a specified value,
The above object is achieved by forming a land for defect marking on the pattern forming surface of the decircuit board, and forming and displaying a defect mark on the land using a laser.

Examples of L invention] FIG. 1 is a diagram showing an embodiment of the method of the present invention.

In the figure, 1o is a decircuit board, and lands 12 for defect marking are formed on the pattern forming surface 11 of the board. In this example, the defect marking run I" 12 is formed in the margin of the pattern forming surface 11 in a state that is electrically independent of the wiring pattern 13, and is a square land larger than about 0.8 mm square. 12 is formed together with the conductor pattern when the conductor pattern is formed.When the number of film resistors is large and laser trimming is performed in multiple steps.

A number of lands 12 for defect marking corresponding to the number of times
is formed. That is, when trimming the film resistance on the decircuiting board 1O is performed, for example, five times, 55 lands 12 for defective marking are formed.
Assigned each time.

A defective mark is formed and displayed on such a defect marking land 12 using a laser when the resistance value after trimming does not match a specified value. As a defect mark, different characters or symbols are formed and displayed for each defect so that it can be distinguished whether the resistance value after trimming is higher than the specified value or lower than the specified value. It is desirable to prepare two types of characters that are different from each other, and make these characters correspond to failures when the value is higher than the specified value and failure when the value is lower than the specified value, and when a failure occurs, the trimmed resistance value is displayed. This is achieved by controlling a laser trimmer to form and display corresponding characters depending on the size of the character relative to the specified value.

This makes it easy to distinguish between those whose cuts are shallow and can be corrected by trimming, and those whose cuts are too deep and cannot be corrected. When trimming is performed multiple times, a defect mark is formed and displayed on the defect marking land 12 corresponding to the number of times of trimming in which the defect occurred. As a result, it is possible to easily determine at which trimming number the defect has occurred, and it is possible to quickly take measures against the defect.

FIG. 2 is a diagram showing another embodiment of the method of the present invention, and its feature is that a land 14 for defect marking is placed on a wiring pattern 13.
The purpose is to form it as a so-called throwaway pattern associated with. According to this, the space can be narrowed by the amount of separation from the wiring pattern compared to the case of the previous embodiment, which is effective when a large space cannot be taken.

In each of the embodiments described above, a square land for defect marking is used as an example, but it is of course possible to use any other shape.

[Effects of the Invention] As explained above, according to the present invention, a land for defect marking is formed on the pattern forming surface of the film facing path substrate, and a defect mark is formed and displayed on this land using a laser. To prevent circuit patterns from being destroyed or oxidation deterioration of lands of individual components such as transistors due to the formation of defective marks, and to be able to rescue correctable defects and improve yields. I can do it.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the method of the present invention, FIG. 2 is a diagram showing another embodiment of the method of the present invention, and FIGS. 3 and 4 are diagrams each showing a conventional example of defect display. . io:g circuit board 11: pattern forming surface

Claims (1)

[Claims] In a method of forming and displaying a defective mark using a laser on a pattern-formed surface of a decircuited circuit board when a resistance value after laser trimming does not match a specified value, a land for defect marking is formed on the pattern-formed surface of the film circuit board. A method for indicating a defective film circuit board, characterized in that a defective mark is formed and displayed on the land using a laser.