JPH07123188B2 - Method for detecting misalignment of multilayer printed circuit board - Google Patents

Description

The present invention relates to a method for detecting misalignment of a multilayer printed circuit board.

"Explanation of the prior art" To mount electrical parts on a printed circuit board with high density, 3
A multilayer printed circuit board is used in which conductor layers of more than one layer are integrated via an insulator. The multilayer printed circuit board may be displaced from the designed position of the conductor layer during the manufacturing process. There are the following methods for checking whether or not the conductor layer is displaced from the designed position.

A plurality of conductor layers are integrated with each other through an insulator, and then a hole is formed to form a through hole for electrically connecting a conductor between each layer or an electric component mounted on the multilayer printed board. A conductor that is electrically connected to a conductor of another layer or the like through a through hole formed in a predetermined hole should be exposed on the inner surface of this hole. Therefore, for example, by using a stereoscopic microscope, it is possible to check the misalignment by immediately checking whether or not the conductor of another layer or the conductor to be electrically connected to the electric component is exposed on the inner surface of each hole immediately after the hole is formed. It is determined whether or not it is happening. However, when a conductor is distributed over a wide area, there is a problem that it is not possible to detect whether or not the misalignment is within an allowable value even if the conductor largely deviates from the set position.

There is also a method of irradiating X-rays around the holes after making the holes to examine how the conductors are distributed. However, in this case, the more layers, the weaker the contrast,
It becomes difficult to judge whether or not there is a misalignment.

Further, as shown in FIG. 3, there is also a method in which coupons 3 and 4 are provided on the product outer peripheral portion 2 of the multilayer printed circuit board 1 to check whether or not there is a misalignment.

In this case, in addition to the conductor for the circuit pattern, the conductor for the coupon for each layer is arranged at the position indicated by the solid line of the coupons 3 and 4 and integrated through the insulator, and then the product is moved in the direction indicated by the dotted line. The outer peripheral portion 2 is cut. At this time, the cut surface is as shown in FIG. If there is a conductor layer 3'having a large misalignment, this printed circuit board is regarded as a defective product. This method has a problem that it takes much time to cut the coupon part after each integration.

"Means for Solving Problems" In the alignment deviation detection method according to the present invention, the alignment deviation detection pattern is provided in a portion of the multilayer printed circuit board where material shrinkage or processing error is large. This includes two through holes and a conductor that is provided in each layer and is designed to electrically connect one through hole and to separate the other through hole by a tolerance value x. It is composed of Therefore, when the misalignment is smaller than the allowable value x, the two through holes are insulated, but when the misalignment is larger than the allowable value x, the two through holes are electrically connected. Since it is only necessary to check whether or not the pair of through holes are insulated in this way, it is possible to relatively easily detect the misalignment of the allowable value x or more.

[Example] Fig. 1 shows a top view of a multilayer printed circuit board 1 provided with a pattern for detecting a misalignment. This consists of eight alignment deviation detection patterns 5 on the outer peripheral portion 2 of the product, which have large material shrinkage and processing errors.
Is provided. Each of the misalignment detection patterns includes a pair of through holes 6 and 7. Through these
The holes 6 and 7 are surrounded by conductors 8 in the outer layer, but are insulated from each other. FIG. 2 shows a design example of the alignment deviation detecting pattern 5 in the inner layer portion. In the inner layer portion, the conductor 9 is designed to be electrically connected to one through hole 7 but separated from the other through hole 6 by an allowable value x. Therefore, when a multilayer printed circuit board is manufactured as designed, two through holes 6 and 7 are formed.
Is insulated.

The conductors 8 and 9 are integrated with the conductor of the circuit pattern via an insulator. Then, holes are formed at positions corresponding to the through holes 6 and 7 of each alignment deviation detection pattern, and the inner surfaces of the holes are metal-plated to form the through holes 6 and 7. By checking whether or not the through holes 6 and 7 are insulated, it is possible to check whether or not there is a misalignment of the allowable value x or more. That is, when there is a region where the misalignment of the allowable value x or more occurs, the conductor 9 electrically connected to one of the through holes 7 of the misalignment detecting pattern 5 at that portion has the allowable value x or more. It shifts and is also electrically connected to the other through hole 6. Therefore, it can be seen that the through holes 6 and 7 are brought into conduction and a misalignment occurs.

In Fig. 1 and Fig. 2, one through
The holes 6 are electrically commonly connected, and the other through hole 7 is electrically commonly connected in the inner layer portion. Therefore, when the misalignment of the allowable value x or more occurs at one location, the two through holes 6 and 7 are electrically connected in all the misalignment detection patterns 5. That is, by measuring the insulation state of the through holes 6 and 7 of any one of the misalignment detection patterns, it is possible to determine whether the misalignment has occurred in the entire multilayer printed circuit board.

As described above, in the present invention, the pair of through holes and one of the pair of through holes in each layer are electrically connected and the other through hole is formed. A misalignment detection pattern composed of a conductor designed to be separated from the hole by an allowable value is created in parallel with the creation of the multilayer printed board. Then, by checking the insulation state of the pair of through holes to determine whether or not the misalignment occurs, it is possible to reliably detect the misalignment by a relatively simple method.

[Brief description of drawings]

FIG. 1 is a top view of a multilayer printed circuit board provided with an alignment deviation detection pattern showing an embodiment of the present invention, and FIG. 2 constitutes an alignment deviation detection pattern in an inner layer portion of the multilayer printed board. Sectional view showing an example of arrangement of conductors, third
The figure shows a top view of a multilayer printed circuit board with coupons, 4th
The drawing is a cross-sectional view showing an example when the coupon portion of the multilayer printed circuit board shown in FIG. 3 is broken.

Claims (1)

[Claims] 1. A. Multiple pairs of through holes, wherein one through hole in each pair is all electrically connected and the other through hole is electrically isolated from said one through hole. B. is arranged between the respective layers, and is electrically connected to each of the other through holes, and is configured to be separated from the one of the through holes by an alignment deviation allowable value and electrically. And a matching deviation detecting pattern consisting of a conductor integrated with the conductor are formed in parallel with the formation of the multilayer printed circuit board, and one of the plurality of pairs of through holes and one of the above through holes and the other of the above through holes are formed. A misalignment detection method for a multilayer printed circuit board, characterized in that the misalignment is detected by checking whether or not the through-holes are insulated.