JPH0558509B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a circuit board inspection device used in the electrical equipment assembly industry, particularly in the electrical circuit board assembly industry.

In recent years, as the packaging density of components has increased, surface-mounted components have come to be used in place of conventional pin-inserted components. As a result, inspection after soldering has become difficult. The two main problems are that the high electrode density makes it difficult to handle with conventional pin probes, and the solder is hidden under the component, making visual inspection difficult. .

The present invention relates to a surface mount circuit board inspection apparatus that is equipped with a new probing means that does not have the above-mentioned problems instead of a pin probe.

(Prior Art) Conventionally, visual inspection and inspection using a pin probe have been performed.

However, visual inspection becomes extremely difficult when the pins are bent and soldered under the component, such as in a J-lead PLCC.
Similarly, when the electrode pitch of a J-lead PLCC becomes smaller, inspection using a pin probe becomes difficult.
Conventionally, such cases were dealt with by providing a land for the pin to be placed at a position slightly away from the component, but this reduced the mounting density and contradicted the purpose of surface mounting. I will do it.

Further, as a known example similar to the present invention, a test clip in which a thin metal wire is embedded inside an elastic insulator has been proposed (Japanese Utility Model Publication No. 56-68167).

(Problems to be Solved by the Invention) However, since the above-mentioned known example simply embeds a thin metal wire inside an insulator, it is not suitable as an inspection device for determining the quality of solder.

One of the objects of the present invention is to provide an apparatus that can perform probing in the immediate vicinity of an IC package with a high pin density without having to take the trouble of providing a land for inspection. Another purpose is to provide a device that can inspect the quality of soldering by direct probing without relying on vision when the pins protrude from the side of the component, but the soldering is done under the component, such as in J-lead PLCCs. It's about doing.

(Means for Solving the Problem) In order to achieve the above object, the circuit board inspection apparatus of the present invention is an apparatus for inspecting soldering of lead wires of an IC package surface-mounted on a circuit on a board. It is equipped with a columnar and hollow silicone hardened rubber block that is taller than the IC package, and a plurality of thin metal wires for contacting the circuit on the board are buried inside the rubber block in the height direction, and the rubber block is covered. Wire the wires so that their tips are exposed from the surface that contacts the test board, and run multiple thin metal wires for contacting the lead wires in the height direction of the inner wall surface of the hollow part of the rubber block so that they do not contact the circuits on the board. It is characterized by being wired as follows.

In the above configuration, it is preferable that the thickness of the thin metal wire is 1/2 or less of the buried pitch.

The present invention will be described below with reference to Examples and drawings.

Figure 1 a shows an IC soldered on the board.
This is a cross-sectional view showing the state of the metal/rubber composite probe just before it enters probing with respect to the package. In the figure, a circuit 2 formed on a substrate 1 and a lead wire 3 coming out from an IC package 4 are connected by solder.

FIG. 1b shows a metal/rubber composite probe consisting of a rubber block 5 and a metal wire 6 as seen diagonally from below, and the metal wire 6 is exposed from the bottom surface of the rubber block 5.

FIG. 1c is a sectional view showing a state in which probing has been completed. In the figure, the metal wire 6 is in contact with the circuit 2. In this state, the metal wire 6 is normally slightly bent and deformed. moreover,
In this figure, the holes formed on the bottom surface of the rubber block serve as guides for alignment. Although the role of a guide is not necessarily essential, and the inner surface of the hole does not need to be in close contact with the package or the pins protruding from the package, such a guide mechanism is useful for aligning the end of the metal wire with the circuit. This is a desirable feature in order to ensure accuracy.

In this way, it is possible to probe circuits close to the IC package, which would be impossible to reach with pin probes. Through a group of metal wires 6
The quality of the solder and the IC function can be checked by electrical signals given to the IC or detected by the IC.

FIG. 2 differs from FIG. 1 in that another set of metal wires is arranged along the inner wall of the hole provided in the rubber block 5. The metal wire 7 arranged along the inner wall is shortened so that it connects to the lead wire 3 and does not connect directly to the circuit 2. With this structure, if circuit 2 and lead wire 3
If the solder between them is defective and the electrical connection is not established, the corresponding metal wires 6 and 7 will become open, making it easy to determine that they are defective. According to this method, it is possible to judge whether the solder is good or bad only by an open shot test. The open short test has the advantage that the test time is shorter than the functional test, so if you only want to determine whether the solder is good or bad, the open short test is more advantageous.

FIG. 3 illustrates an assembly method for extracting electrical signals from the metal/rubber composite probe to the outside. In this figure, metal wires 8 and 9 are embedded in an insulating resin block 10 and are drawn out while maintaining mutual insulation. The metal/rubber composite probe can be attached to and removed from the resin block 10. In the attached state, the metal wires 6 and 7 are in contact with the metal wires 8 and 9, respectively, and are electrically connected thereto.

The resin block 10 is fitted and fixed in the cylinder inner tube 11, and the probe is pressed down with an appropriate force by the action of a spring 13. The cylinder outer cylinder 12 is fitted into and fixed to a fixing plate 14. A plurality of probes of the same type and conventional pin probes can be attached to the fixing plate 14 at the same time.

FIG. 4 shows another example of assembly. rubber block 10
is attached directly to the cylinder inner tube 11, and the metal wires 6, 7 are embedded in the rubber block.
The other end is pulled out directly from the top.

The material of the rubber block must have so-called rubber elasticity and be electrically insulating. silicone rubber, urethane rubber, butadiene rubber,
Nitrile-butadiene rubber, butadiene-styrene rubber, and various other rubbers can be used, but silicone rubber is especially easy to mold because cured rubber can be easily obtained from liquid raw materials, and it has excellent insulation properties and elasticity retention. It is particularly preferable because

The metal wire buried in the rubber block is gold,
Thin wires made of copper, phosphor bronze, nickel, aluminum, tin, or stainless steel are preferably used. A composite of two or more materials by plating, cladding or other means may also be used. For example, a fine wire made of phosphor bronze, which has excellent spring elasticity, and whose surface is plated with gold, which has excellent electrical connection properties, is particularly suitable. The cross-sectional shape of this thin wire is not particularly limited, such as circular, elliptical, or rectangular, but a shape close to circular is preferably used. It is preferable that the thickness of this thin wire is such that its long axis does not exceed the buried pitch. In particular, it is preferably 1/2 or less of the buried pitch.

A composite probe consisting of a rubber block and a metal wire can be made one by one by cast molding, or by obtaining a long cylindrical object by extrusion molding or cast molding, and then cutting it into rings. It can also be made by cutting a part of it if necessary.

(Effects of the Invention) The apparatus of the present invention has a remarkable effect in that an IC package with a high pin density can be inspected by probing right next to the package. In addition, when the pins protrude from the side of the component, such as in J-lead PLCCs, but the soldering is done under the component, the quality of the solder can be inspected by direct probing without relying on the visual sense, increasing the accuracy of the inspection. and speed can be ensured.

[Brief explanation of the drawing]

FIGS. 1 and 2 show how probing is performed in the apparatus of the present invention. In the figure, a is a cross-sectional view showing the state immediately before probing, and c is a cross-sectional view showing the state at the time when probing is being performed.
b is a partial view of the probe viewed diagonally from below.
FIGS. 3 and 4 show an example of a method for assembling a probe in the apparatus of the present invention.

Claims (1)

[Scope of Claims] 1. An apparatus for inspecting soldering of lead wires of an IC package surface-mounted on a circuit on a board, comprising a columnar and hollow silicone cured rubber block taller than the IC package, A plurality of thin metal wires for contacting the circuits on the board are embedded in the rubber block in the height direction, and wired so that the ends of the rubber block are exposed from the surface where the rubber block contacts the board to be inspected. A circuit board inspection device characterized in that a plurality of thin metal wires for contact are wired in the height direction of the inner wall surface of the hollow portion of the rubber block so as not to contact the circuits on the board. 2. The circuit board inspection device according to claim 1, wherein the thickness of the thin metal wire is 1/2 or less of the buried pitch.