JPH05133978A - Probe pin for electrically inspecting printed wiring board - Google Patents

Abstract

PURPOSE:To surely detect a disconnecting fault in the through hole of a printed wiring board even when the through hole gets clogged with solder at the time of performing electrical inspection on the wiring board for checking the continuity, propriety of insulation, etc., of the circuit pattern of the printed wiring board. CONSTITUTION:Only the front end section of a probe pin 10 to be brought into contact with the through holes, etc., of printed wiring boards is selectively coated with a hard insulator 10b. At the time of inspecting a through hole which gets clogged with solder, the insulator at the front end of the pin 1 is brought into contact with the solder clogging the hole so as to produce insufficient continuity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe pin for electrical inspection of a printed wiring board, and more particularly to an inspection probe for inspecting the continuity of a circuit pattern of the printed wiring board or judging the quality of insulation. As for the probe pin to be brought into contact with the surface mounting pad or through hole.

[0002]

2. Description of the Related Art In recent years, electronic parts such as flat package type or chip type have been mounted on the main surface of a printed wiring board in response to demands for higher performance, smaller size and lower cost of equipment. A surface mounting method is used in which the conductor pattern is connected to a predetermined pad of a conductor pattern formed on the main surface.

The electrical inspection of the above-mentioned printed wiring board for surface mounting is generally performed as follows. That is, for example, as shown in a side view in FIG. 5, using a probe pin 1 formed of a conductive metal in a substantially conical shape,
This is applied to the required surface mounting pad of the printed wiring board. Further, as shown in a sectional view in FIG. 6, the two probe pins 1 are inserted into the through holes 3 of the printed wiring board 2 for interlayer conduction or component mounting from both sides, respectively, and The outer peripheral surface is brought into contact with the conductor layer 4 on the inner wall surface of the through hole 3, respectively. By applying an appropriate voltage between the probe pins 1, the pads and the through holes 3 are inspected for electrical continuity, and circuit continuity inspection and insulation pass / fail judgment are performed.

[0004]

However, in the conventional inspection method using the probe pin 1, the conductor layer 4 in the through hole 3 has a disconnection defect as shown in a sectional view in FIG. In addition, when the solder 5 is clogged in the hole, conduction between the probe pins 1 can be achieved by the clogged solder 5, so that it is impossible to detect a disconnection defect.

When manufacturing the printed wiring board 2,
After solder coating, which is one of the final processing steps, clogging of the solder 5 holes in the through holes 3 for mounting components is inspected and removed by a hole checker as described below. That is, as shown in a sectional view in FIG. 8, for example, the amount of light 7 emitted from the fluorescent lamp 6 that passes through the through hole 3 is sensed by, for example, the CCD sensor 8, and the number of holes is measured and detected. The presence or absence of clogging of the solder 5 holes is inspected by the hole checker 9 configured to judge the quality of the holes depending on the number of holes. However, such a hole checker 9 may malfunction due to an end face burr or dust generated on the printed wiring board 2 during press working. Therefore, the inspection accuracy is not always high, and the printed wiring with the clogging of the solder 5 holes is not necessarily required. The plate 2 was not extracted and flowed into the electrical inspection process, which was a cause of the above problems.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a probe pin capable of reliably detecting a disconnection defect of a through hole in an electrical inspection of a printed wiring board. ..

[0007]

A probe pin for electrical inspection of a printed wiring board according to the present invention is brought into contact with a surface mounting pad or a through hole formed on a main surface of the printed wiring board for electrical inspection. In order to perform the above, the conductive metal probe pin formed in a substantially conical shape is characterized in that the tip end portion of the probe pin is selectively covered with a hard insulator.

[0008]

According to the probe pin of the present invention, since the surface of the tip end portion is covered with a hard insulator, the probe pin is brought into contact with the surface mounting pad or through hole of the printed wiring board for electrical inspection. When used as a probe, in a through hole with a clogged solder hole, the insulator at the tip comes into contact with the solder clogged in the hole, so conduction between probe pins is not detected and it is determined to be defective. ..

If the through holes are clogged with solder holes as described above, all of them are determined to be defective in conduction and are extracted.
It is possible to reliably detect a printed wiring board with solder clogging without erroneously overlooking a defect in the hole in the printed wiring board.

[0010]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a partially cutaway sectional view showing an example of the structure of an electrical test probe pin according to the present invention.
The probe pin 10 includes a main body 10a formed of a conductive metal such as copper in a substantially conical shape, and an insulating coating layer such as Teflon (fluororesin) provided to cover the outer circumference of the tip of the main body 10a. It consists of 10b and.

When the probe pin 10 having such a structure is used and the printed wiring board 2 is electrically inspected as shown in a sectional view in FIG. 2, there is a break in the conductor layer 4 in the through hole 3 and the solder 5 is present. In the through hole 3 in which the hole is clogged, the insulating coating layer 10b such as Teflon at the tip of the probe pin 10 comes into contact with the solder 5 that is clogged in the through hole 3, so that the electrical inspection result is poor continuity, that is, disconnection. ..

Further, as shown in a sectional view in FIG. 3, when the probe pin 10 having the above-mentioned structure is inserted into a normal through hole 3 in which the solder 5 hole is not clogged and the conductive layer 4 in the through hole is not broken, a conductive metal is used. Since the pin main body portion 10a made of (3) contacts the conductor layer 4 on the inner wall surface of the through hole 3, normal conduction is detected.

Thus, the probe pin 10 according to the present invention
According to this, it is possible to easily and surely detect the disconnection in the through hole 3 in the case where there is clogging of the solder 5 hole, which cannot be detected conventionally. Also, when the printed wiring board 2 is pressed at the end, the hole checker malfunctions due to dust or the like on the end surface of the printed wiring board 2. When the printed wiring board 2 having the solder 5 hole clogging is mixed in the electrical inspection process, the hole clogging occurs. It is possible to reliably detect the through hole in which the defect occurs and remove it as a defective product.

FIG. 4 is a cross-sectional view showing another example of the structure of the probe pin according to the present invention with a part thereof cut away. At the tip of the main body 10a formed of conductive metal in a substantially conical shape, It has a structure in which an insulating portion 10b made of hard glass is bonded and embedded. Therefore, as in the case of the above-described configuration example, it is possible to reliably detect the disconnection in the through hole 3 when there is clogging of the solder 5 hole, which cannot be detected conventionally.

[0016]

As described above, according to the probe pin for electrical inspection of the present invention, even when the printed wiring board has a clogging of the solder hole, the disconnection defect of the conductor layer in the through hole is accurately detected and extracted. Can be eliminated. In addition, even when a printed wiring board having a clogged solder hole is included in the electrical inspection process without being extracted in the optical check process, such a defect can be easily detected and extracted.

[Brief description of drawings]

FIG. 1 is a partially cutaway cross-sectional view showing a structural example of a probe pin for electrical inspection according to the present invention.

FIG. 2 is a cross-sectional view showing a state in which the probe pin for electrical inspection according to the present invention is brought into contact with a through hole of a printed wiring board having a defective hole disconnection and a clogged solder hole.

FIG. 3 is a cross-sectional view showing a state in which the probe pin for electrical inspection according to the present invention is brought into contact with a through hole of a normal printed wiring board.

FIG. 4 is a partially cutaway sectional view showing another structural example of the probe pin for electrical inspection according to the present invention.

FIG. 5 is a side view showing a structure of a conventional probe pin for electrical inspection.

FIG. 6 is a cross-sectional view showing a state in which a conventional probe pin is brought into contact with a through hole of a normal printed wiring board.

FIG. 7 is a cross-sectional view showing a state in which a conventional probe pin is brought into contact with a through hole of a printed wiring board having a defective hole disconnection and a clogged solder hole.

FIG. 8 is a side view showing a schematic configuration of hardware of a hole checker for a pudding and a wiring board.

[Explanation of symbols]

1, 10 ... Probe pins 2 ... Printed wiring board 3 ...
Through hole 4 ... Conductor layer on inner wall surface of through hole 5 ...
Solder 6 ... Fluorescent lamp 7 ... Light 8 ... CCD sensor
9 ... Hole checker 10a ... Probe pin body
10b… Insulation coating layer

Claims (1)

[Claims] 1. A conductive metal probe pin formed in a substantially conical shape for contacting a surface mounting pad or a through hole formed on a main surface of a printed wiring board to perform an electrical inspection. A probe pin for electrical inspection of a printed wiring board, characterized in that the tip of the pin is selectively covered with a hard insulator.