JPH06194399A - Inspection method for printed wiring board - Google Patents

Abstract

PURPOSE:To eliminate the need of precise alignment of probe while simplifying an inspection equipment and shortening the time required for arrangement by inspecting disconnection of a conductive line while touching an inspection probe and a flexible conductive piece, respectively, to one and the other ends of the conductive line. CONSTITUTION:An inspection probe 8 is held by a holder 6 while touching one ends of the conductive lines 3 of 8 plurality of printed wiring circuits 1 formed on a printed circuit board 4 mounted on a table 5. A flexible conductive piece 9 of such size as covering other conductive line 3 together touches the other end of the conductive line 3 while being aligned roughly, thus inspecting disconnection of the conductive line 3. A presser having a power source of pneumatic pressure or an electromagnet is employed for touching the flexible conductive piece 9 to the conductive line 3 and connecting them electrically. When the conductive line 3 is not disconnected, a closed circuit is established between the inspection probe 8 and the flexible conductive piece 9 and propriety of the conductive line can be decided basing on the number of pulses being produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a printed wiring circuit formed using conductive ink.

[0002]

2. Description of the Related Art Generally, a printed wiring circuit 1 is formed by printing a plurality of conductive lines 3 on a substrate 2 made of an electrically insulating resin, as shown in FIG. When this printed wiring circuit 1 is manufactured, a plurality of substrates 2 are formed on one surface of the substrate 2 to form a printed circuit board 4, and then the printed wiring circuits 1 are cut to obtain individual printed wiring circuits 1.

Recently, the conductive lines are becoming finer and are likely to be broken. In order to detect this defect, a probe card in which the number of inspection stylus corresponding to the number of conductive lines of one printed wiring circuit is arranged is aligned with each printed wiring circuit, and the inspection stylus is connected to the conductive line. When the conductive lines have a parallel line pattern and are inspected by contacting both ends of the wire (first inspection method), as disclosed in JP-A-63-85468, it is composed of pins, probes, pin receivers, etc. The inspection device is scanned, and two inspection stylus are brought into contact with both ends of the conductive line for inspection (second inspection method).

[0004]

However, in the first inspection method, it is necessary to prepare a probe card for each type (pattern) of the printed wiring circuit to be inspected, which is costly and requires a precise pitch. Since the inspection stylus is placed, it is necessary to pay close attention to storage and quality control.In addition, when using it, align the probe card precisely to ensure that the inspection stylus is accurately aligned with the conductive line. Since it has to be in contact with the inspection equipment, it is necessary to use an inspection device having a considerably high accuracy.

On the other hand, the second inspection method does not need to prepare a probe card for each type (pattern) of the printed wiring circuit, and is widely used when the conductive lines have a pattern of parallel equal intervals. The procedure of inspection with this probe is
As shown in FIG. 3, the printed circuit board 4 is placed and fixed on the table 5, and the inspection stylus 8 attached to the tip of the probe 7 held in the holder 6 fixes the printed wiring circuit 1 on the printed circuit board 4. An inspection in which the holder 6 is moved in parallel and at right angles to the conductive line 3 so as to be in contact with the conductive line 3, and scanning is performed on the conductive line 3 so that the holder 6 is in contact with both ends of one conductive line. A detector (not shown) detects the presence or absence of a pulse generated on the stylus 8.

However, as electronic equipments using printed wiring circuits have become more sophisticated and miniaturized, the miniaturization of conductive lines has been extremely advanced. Therefore, not only in the first inspection method described above, but also in the second inspection method, the printed circuit board is printed. Both methods are highly accurate because it is not possible to keep the inspection stylus accurately in contact with both ends of the conductive line unless the upper conductive line and the two inspection stylus are accurately scanned at right angles. Had the disadvantage of needing inspection equipment. Furthermore, in the second inspection method, the shapes of the conductive lines are limited to those having parallel and even intervals, so that it is inevitable to exclude those that make use of the feature of the printed wiring circuit that a free shape can be easily formed. Therefore, its application range is limited.

[0007]

SUMMARY OF THE INVENTION The present invention provides a method for inspecting a printed wiring circuit, which solves the above-mentioned conventional problems and can inspect the disconnection of a conductive line on a printed circuit board in a quick and accurate manner. , This is a method for inspecting the electrical characteristics of a conductive line that forms a printed wiring circuit formed on a substrate made of an electrically insulating resin, in which one end of the conductive line has a probe for inspection and the other end has a flexible conductive piece. A gist is a method for inspecting a printed wiring circuit, which is characterized by contacting and inspecting a disconnection of a conductive line.

Since the inspection stylus must not contact two or more conductive lines at the same time when scanning the conductive lines, the thickness and the mounting angle are limited. Since the diameter is reduced to about 0.2 mm pitch, the diameter should be 1 mm or less, preferably 0.5 mm or less, and the tip should be conical, and if it is less than 0.2 mm, processing of the inspection stylus and It is not preferable in terms of strength.

If the mounting angle of the inspection stylus is 90 ° with respect to the surface of the printed circuit board, the conductive line may be damaged by the pressure applied to the inspection stylus to make the electrical contact sufficiently stable. And at extremely low angles,
20 ° to 60 °, preferably 30 °, as it interferes with the mounting method
It is good to set it to ~ 45 °.

Since the material of the inspection stylus is required to have high conductivity and excellent wear resistance, it is selected from nickel, copper, tungsten, steel, etc., but nickel, copper, steel, etc. May oxidize and increase contact resistance, and thus requires anticorrosion treatment such as gold plating. However, no anticorrosion treatment such as gold plating has excellent wear resistance, so tungsten is most preferable.

As described above, the probe for holding and fixing the inspection stylus has conventionally required precise alignment between the inspection stylus and the conductive line, so that the inspection stylus is perpendicular to the conductive line. Although a mechanism for finely moving in the parallel and parallel directions is required, which is complicated and expensive, the present invention does not require it, and the structure can be simple and inexpensive.

Further, since it is necessary to surely bring the probe for inspection into contact with the conductive line, it is preferable to apply a pressure to the probe with a leaf spring or the like. If the applied pressure is too small, contact with the conductive line becomes uncertain, and if too large, the conductive line may be damaged. Therefore, the applied pressure should be in the range of 0.5 to 5 g, preferably 1 to 2 g. Good.

The inspection stylus to be brought into contact with one end of the conductive line requiring inspection and the flexible conductive piece to be brought into contact with the other end are laminated and adhered with copper foil, aluminum foil, etc. on a flexible base material such as polyimide or polyester. It may be a conventionally known one, or may be one in which wiring is provided by printing on the above-mentioned flexible base material as an inspection target.

The flexible conductive piece to be brought into contact with the other end of the conductive line is required to be flexible so as to be able to follow the irregularities of the printed wiring circuit to be inspected. 10 to 50 when using film
The thickness is preferably μm, preferably 20 to 40 μm. Since the flexible conductive piece may be provided with conductivity on at least one surface of the above-mentioned film and connected by the inspection device and the lead wire, it is not necessary to form a special pattern. Other metal foils such as copper foil, aluminum foil and the like may be used as long as they have the same flexibility as films such as polyimide and polyester.

[0015]

The method for inspecting a printed wiring circuit according to the present invention will be described below with reference to the drawings. As shown in FIG. 1, a plurality of printed wiring circuits are formed / imposed on a printed circuit board 4 placed on a table 5. So that it contacts one end of the conductive line 3 of 1.
The holder 6 holding the inspection stylus 8 and the flexible conductive piece 9 of a size that covers the other conductive line together at the other end are roughly aligned and brought into contact with each other to inspect the disconnection of the conductive line. At this time, if there is no disconnection in the conductive line, a closed circuit is formed between the inspection stylus and the flexible conductive piece, so that the quality of the conductive line is determined by the number of generated pulses. Other conductive lines can be judged one after another by moving only the inspection stylus.

In order to electrically connect the flexible conductive piece to the conductive line by contacting it, as shown in FIG. 2A, a conventionally known pressing device such as a cylinder powered by compressed air pressure or an electromagnet is used. 10 may be used. Reference numeral 11 is a lead wire connected to the flexible conductive piece. In this case, it is preferable to press through the sponge 12 in order to evenly distribute the pressure and to follow the irregularities of the printed circuit board to maintain sufficient contact. When the printed wiring circuit to be inspected is in the form of a film or is paramagnetic, as shown in FIG. 2B, the printed wiring circuit 1 inspecting the flexible conductive piece 9 is tested. It may be fixed so as to be sandwiched by the permanent magnets 13 while being in contact with the other end of the conductive line 3. As the permanent magnet, a flexible magnetic tape MGO-1016 (product name of Sumitomo 3M Ltd.) or the like is suitable.

[0017]

As described above, according to the inspection method of the present invention, one end of the conductive line is brought into contact with the inspection stylus and the other end is brought into contact with the flexible conductive piece. There is no need to perform precise alignment, simplification of inspection equipment,
It has become possible to reduce the setup time. Further, the shapes of the conductive lines to be inspected are not limited to those having equal intervals in parallel, and general-purpose inspection is possible.

[Brief description of drawings]

FIG. 1 is an illustration of a method of the present invention for inspecting printed wiring circuits.

FIG. 2 is an explanatory diagram of a conventional inspection method for a printed wiring circuit having parallel evenly spaced conductive lines.

FIG. 3 (a) is an explanatory view of a case where a flexible conductive piece is pressed against a conductive line by a pressing device using pneumatic pressure or an electromagnet as a power source, and FIG. 3 (b) shows a flexible conductive piece conductive by a permanent magnet. Explanatory drawing at the time of pressing on a line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Printed wiring circuit 2 ... Substrate 3 ... Conductive line 4 ... Printed circuit board 5 ... Table 6 ... Holder 7 ... Probe 8 ... Inspection stylus 9 ... Flexible conductive piece 10 ... Pusher 11 ... Lead wire 12 ... Sponge 13 ... Permanent magnet

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[Procedure amendment]

[Submission date] December 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

FIG. 2 (a) is a pressing force using pneumatic pressure or an electromagnet as a power source.
Of pressing a flexible conductive piece against a conductive line with a container
As shown in the figure, (b) shows a flexible conductive piece made of a permanent magnet.
Explanatory diagram of the case for pressing the down. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

FIG. 3 shows a printed wiring circuit having parallel evenly spaced conductive lines.
Explanatory drawing of the conventional inspection method .

Claims (3)

[Claims] 1. A method for inspecting the electrical characteristics of a conductive line that forms a printed wiring circuit formed on a substrate made of an electrically insulating resin, wherein an inspection stylus is provided at one end of the conductive line and a flexible conductive layer is provided at the other end. A method for inspecting a printed wiring circuit, which comprises inspecting a disconnection of a conductive line by bringing pieces into contact with each other. 2. The inspection method according to claim 1, wherein the flexible conductive piece is brought into contact with the other end of the conductive line by a cylinder using pneumatic pressure and electromagnetic force as a power source. 3. The inspection method according to claim 1, wherein the flexible conductive piece is brought into contact with the other end of the conductive line by a permanent magnet.