JP2008098211A - Pattern shape of printed circuit board, and insulation deterioration test method of printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulation deterioration test method of a printed circuit board for checking insulation deterioration direction in nondestructive manner in the process for analyzing insulation deterioration. <P>SOLUTION: A conductor pattern shape surrounding a through-hole is radially divided into n sections keeping constant distance of the through-hole. After the n conductor patterns are set to the equal potential and a voltage is applied to the conductor patterns and the through-hole to conduct the predetermined insulation deterioration test. Thereafter, an insulation resistance between the n conductor patterns and the through-hole is individually measured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for testing insulation deterioration of a printed wiring board and a pattern shape of the printed wiring board.

  An example of an analysis procedure when a short circuit occurs in a conventional insulation deterioration test will be described with reference to FIGS. 4, 5, and 6. FIG. 4 shows a horizontal cross-sectional shape of a printed wiring board for an insulation deterioration test according to the prior art, which is composed of a through hole 1, a conductor pattern 5, and a clearance 7. A printed wiring board that has been subjected to a predetermined insulation deterioration test narrows down through holes that have undergone electrical insulation deterioration and cuts the printed wiring board to a size that is easy to analyze. Next, each layer is cut from one of the front and back layers by horizontal polishing, and until the insulation deterioration 6 is confirmed between the through hole 1 and the conductor pattern 5 as shown in FIG. In the process of grinding, it is necessary to perform polishing while observing with a stereomicroscope or a metal microscope and confirming the presence or absence of insulation deterioration. Furthermore, the figure which grind | polished perpendicularly | vertically with respect to the insulation deterioration location is shown in FIG. An insulation deterioration portion 6 is shown between the conductor pattern 5 and the through hole 1.

  In recent years, since many materials containing fillers and colorants are contained in the resin component of the printed wiring board material, it is difficult to observe the insulation deterioration phenomenon in the foreground because it is difficult to observe with a stereo microscope or a metal microscope. As a result, there are many cases in which the insulation deterioration phenomenon disappears due to excessive shaving in the horizontal polishing stage. Therefore, there is a demand for means for electrically confirming the direction of insulation deterioration before shaving in polishing.

JP 2000-101214 A

  In the analysis of insulation deterioration according to the above-described prior art, the direction of insulation deterioration may not be specified unless horizontal polishing is performed. Moreover, there is a risk that the risk of disappearance of the insulation deterioration phenomenon due to overpolishing may occur as an adverse effect of horizontal polishing.

  An object of the present invention is to provide an insulation deterioration test method for a printed wiring board that can estimate an insulation deterioration location only by electrical confirmation.

  In order to achieve the above object, the present invention is characterized in that the conductor pattern surrounding the through hole is radially divided into n so that the distance between the conductor and the through hole is constant at the design stage of the printed wiring board. In addition, after conducting a predetermined insulation deterioration test by applying a voltage to the conductor pattern and the through-hole with the conductor pattern divided into n equal potentials, the insulation resistance between the n-divided conductor pattern and the through-hole is individually measured. It is characterized by doing.

  By individualizing the inner layer pattern that surrounds the through hole of the conductor pattern, there is an advantage that the location of insulation deterioration can be estimated only by electrical confirmation.

  FIG. 1 is a plan view of a substrate using conductor patterns 3.1 to 3.8 of an insulating deterioration test printed wiring board according to an embodiment of the present invention.

  The structure of the printed wiring board for insulation deterioration test has a plate thickness of 1.6 mm and 10 layers. Among the 10 layers, the inner layer 8 layers excluding the front and back layers surround the through hole 1 with the clearance 2 so that the distance between the conductive patterns 3.1 to 3.8 and the through hole 1 is constant, and the conductive pattern 3.1. To 3.8 are formed by dividing them radially into 8 parts. A printed wiring board was prepared with a structure in which the eight divided conductor patterns 3.1 to 3.8 are not electrically connected.

  The insulation deterioration test conditions were a high-temperature and high-humidity tank, the setting conditions were a temperature of 85 ° C. and a humidity of 85%, and the applied voltage was set to 100V. Before the test, a total of nine wires were applied, one for the through hole 1 and one for the conductor pattern 3 divided into eight. For voltage application, the conductor patterns 3.1 to 3.8, which were divided into eight with the through-hole 1 as a cathode, were bundled into eight pieces to make an anode. Before the test, the circuit tester was used to check whether the cathode and anode were short-circuited, and a printed wiring board was installed in the test tank. The insulation deterioration state during the test was confirmed by voltage monitoring with a hybrid recorder. After insulation deterioration occurs, the test is stopped, the sample is taken out, the bundled anode is separated into 8 parts, the resistance of the cathode and anode is measured with a circuit tester, and the shorted point is the fourth layer conductor The pattern was identified as 3.7 (FIG. 2).

  Next, when carrying out the failure analysis, it was decided to analyze according to the conventional failure analysis procedure whether there was an electrically confirmed direction of insulation deterioration. The substrate was cut slightly larger than the region including the insulation degradation point that could be electrically confirmed, and polished one by one with horizontal polishing, while confirming the resistance with a stereomicroscope, metal microscope and circuit tester. The conductor pattern 3.7 (FIG. 2) and the insulation degradation location 4 which were insulation-deteriorating before the 4th layer were confirmed. Further, polishing is performed in the vertical direction in parallel with the location where the insulation is deteriorated, and polishing is performed using a stereomicroscope and a metal microscope, and the insulation deterioration portion 4 is formed between the conductive pattern 3.7 and the through hole 1 shown in FIG. The insulation deterioration phenomenon that carbonized along the cloth was confirmed.

  Based on the above analysis, the insulation deterioration direction confirmed electrically can be verified by using the conductor patterns 3.1 to 3.8 according to the present invention because the insulation deterioration directions confirmed by horizontal polishing and vertical polishing are the same. We were able to. From this result, it is possible to electrically identify the direction of insulation deterioration even in materials that have been used in recent years, such as filler-filled materials, thereby eliminating the need to specify the direction of insulation deterioration in horizontal polishing, which has been performed in the past, and shortening analysis time and failure analysis Insulation deterioration phenomenon can be easily confirmed.

It is a top view which shows the conductor pattern by this invention. It is a top view which shows the insulation degradation location by this invention. It is sectional drawing which shows the insulation degradation location by this invention. It is a top view which shows the conventional conductor pattern. It is a top view which shows the conventional insulation degradation location. It is sectional drawing which shows the conventional insulation deterioration location.

Explanation of symbols

1: Through hole 2: Clearance 3.1 to 3.8: Conductor pattern 4: Insulation deterioration place 5: Conductor pattern 6: Insulation deterioration place 7: Clearance

Claims (2)

  A conductor pattern shape of a printed wiring board, wherein a conductor pattern surrounding a through hole is radially divided into n so that the distance between the conductor and the through hole is constant in the conductor pattern of the printed wiring board for insulation deterioration test. In the printed circuit board for insulation deterioration test using the conductor pattern according to claim 1, after conducting a predetermined insulation deterioration test by applying a voltage to the conductor pattern and the through hole with the conductor pattern divided into n equal potentials. An insulation deterioration test method for a printed wiring board, wherein the insulation resistance between the n-divided conductor pattern and the through hole is individually measured.

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