JP2002122623A - Short circuit detecting device for circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a short circuit detection device for a printed circuit board formed with lead wirings for an LSI or the like, capable of easily detecting a short circuit between the lead wirings in a connecting state of all the lead wirings to a conductor frame for the purpose of plating treatment. SOLUTION: This short circuit detection device for the circuit board having plural frame cells with the plural lead wirings connected to the conductor frame comprises a magnetic flux generation part having magnetic cores along the conductor frame between the adjacent frame cells, facing to the circuit board; magnetic flux-circulating magnetic plates; and a current detection means. By crossing alternate magnetic flux or pulse flux to the conductor frame according to drive current for coils and detecting current flowing between the lead wirings by the current detection means, the presence of the short circuit is decided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for a printed circuit board, and more particularly to an inspection apparatus for detecting the presence or absence of a short circuit between lines.

[0002]

2. Description of the Related Art A printed circuit board on which electronic components are mounted is manufactured using a thin film forming technique such as etching and plating. With higher functionality, the density of mounted components is higher, and the gap between wires is becoming smaller year by year. Pre-inspection of printed circuit boards, which are difficult to correct after mounting due to high density, is becoming increasingly important, but the difficulty is also increasing due to the high density. Conventionally, a continuity or non-conduction test is generally performed by contacting or non-contacting each of the wiring patterns on the printed circuit board. However, it is not easy to detect a short circuit between the lead wires when all the lead wires are connected to a conductor frame for plating on a printed circuit board on which lead wires such as an LSI are formed. Was.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a printed circuit board on which lead wiring such as an LSI is formed, in a state where all the lead wiring are connected to a conductor frame for plating. An object of the present invention is to realize an inspection apparatus that can easily detect and output a short circuit between these lead wires.

[0004]

According to the present invention, there is provided an apparatus for detecting a short circuit in a circuit board having a plurality of frame cells having a plurality of lead wires connected to a conductor frame as a common conductor. It is composed of a magnetic flux generating part disposed opposite, a magnetic plate disposed on the opposite side of the magnetic flux generating part with respect to the circuit board, and current detecting means, and the magnetic flux generating part is disposed on each of the conductor frames on four sides of the frame cell A magnetic core for driving the magnetic core, a magnetic plate for magnetic flux recirculation has a cutout for connection to a lead wiring at the center of the frame cell, and a current detecting means is connected to the lead wiring from the cutout. And a magnetic flux generating section for generating an alternating magnetic flux or a pulse magnetic flux by the coil and supplying the magnetic flux to the conductor frame so as to be substantially perpendicular to the conductor frame. Possible to determine the short-circuit portion existence between the lead wires from the amount of the current induced to provide realize a short circuit detecting device of the circuit board, wherein the.

That is, a current is induced in a closed circuit composed of a conductor frame, a lead wire, and an ammeter. If a short circuit exists, the current induced in the short circuit, the lead wire, and the closed circuit of the ammeter is generated. Detects a decrease from the former. The degree of the induced current between the lead wires is stored in advance, and the presence or absence of a short circuit is determined by comparing the measured value at the inspection stage with the measured value.

According to the circuit board short circuit detecting apparatus described above, the amount of current induced in a closed circuit constituted by a conductor frame to which a large number of lead wires are connected, a lead wire, and an ammeter is monitored. A short circuit between lead wires can be reliably detected.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of a short circuit detecting apparatus for a circuit board according to the present invention.

FIG. 1 shows an example of a wiring pattern of a lead wiring board such as an LSI, which is a target of the circuit board short circuit detecting apparatus according to the present invention. In the figure, reference numeral 11 denotes a contact portion of an external lead wire of an LSI or the like, reference numeral 12 denotes a lead wiring thereof, and reference numeral 13 denotes a conductor formed for applying electroplating to the contact portion 11, the lead wiring 12, and the like. Each shows a frame. The area surrounded by the conductor frame 13 is referred to as a frame cell for convenience. A large number of the frame cells are formed adjacent to each other on the circuit board, and are cut and separated along the conductor frame 13 for practical use. Is done.

Reference numeral 14 denotes a part of the conductor frame 13 and the lead wiring in an enlarged manner, and the lead wirings 16 and 17 and the short wiring 18 are shown. An area indicated by reference numeral 15 indicates an area to be cut and removed along the conductor frame.

In FIG. 1, the purpose is to accurately detect the short-circuit portion 18.
In the state where the wirings 6 and 17 are connected, it is difficult to determine even if the resistance between the respective lead wirings 16 and 17 is checked at the contact portion 11. In the present invention, when a current is induced in the conductor frame 13 and the short-circuit portion 18 is present, the presence or absence of the short-circuit portion 18 is determined by utilizing the fact that the current hardly flows between the lead wires 16 and 17.

FIGS. 2, 3, and 4 show a first embodiment of a circuit board short circuit detecting apparatus according to the present invention, and the principle of operation of the present invention will be described with reference to these figures. FIG.
FIG. 3 is a plan view from above, FIG. 3 is a side view thereof, and FIG. 4 is a diagram showing a relationship between a magnetic flux and a closed circuit to which an ammeter is connected.

FIG. 2 shows the conductor frame 13 for easy understanding.
And magnetic cores and coils arranged around the frame cells 21 and 22, and a magnetic body arranged on the opposite side with respect to the circuit board and a magnetic body arranged at an end of the magnetic core to constitute a magnetic circuit are omitted. These will be described with reference to the side view in FIG. In FIG. 1, independent magnetic cores 2 are provided on conductor frames 13 on four sides constituting a frame cell.
3, 25, 27, 29 and 2b are arranged, and coils 24, 26, 28, 2a and 2c are arranged in the respective magnetic cores. The magnetic cores adjacent to the four corners of each frame cell, for example, the magnetic cores 23 and 25, are arranged with a gap as much as possible to avoid a magnetic short circuit. The relationship between the line width of the conductor frame 13 and the thickness of the facing portion of the magnetic core is such that the latter is slightly smaller than the former, so that a short-circuit portion (number 18 in FIG. 1) close to the conductor frame 13 can be detected. Although desirable from the viewpoint, the degree is determined in consideration of the positional accuracy between the magnetic core group and the conductor frame, or the accuracy such as the line width and the magnetic core thickness.

FIG. 3 shows the magnetic cores 23, 25, 27, 29 and 2b around the frame cells 21 and 22 and the magnetic materials and the like associated with the coils 24, 26, 28, 2a and 2c wound therearound. Show. In the figure, the conductor frame 13 shows only a cross-sectional view of a portion facing the magnetic cores 23, 27 and 2b, and numeral 35 indicates a circuit board having the conductor frame 13. The short-circuit detecting apparatus for a circuit board according to the embodiment includes, in addition to the magnetic cores and the coil groups shown in FIG. , 27 and 2b are not connected to the circuit board 35, and are magnetically connected to form a first magnetic plate 31 and a magnetic core group 2 for forming a magnetic circuit.
The second magnetic plate 32 forms a magnetic circuit by magnetically connecting the ends of the 5 and 29 that are not opposed to the circuit board 35.

The first magnetic plate 31 magnetically connects the ends of the magnetic core groups 23, 27 and 2b on the sides of the frame cells 21 and 22 in FIG. The second magnetic plate 32 magnetically connects the ends of the magnetic core groups 25 and 29 on the sides facing the frame cells 21 and 22 in the longitudinal direction. They can be composed of magnetic strips in the horizontal and vertical directions, respectively. However, considering the simplicity of construction, the second magnetic plate 32 is a planar magnetic plate, and the first magnetic plate 31 is a magnetic plate. It is structurally simpler to form a magnetic plate in which a portion near the core groups 25 and 29 is cut out so as not to approach the core groups 25 and 29. If the gap member 33 between the first and second magnetic plates 31 and 32 is made of a non-magnetic material, either resin or metal, the primary purpose can be achieved, but in this embodiment, a copper plate is used.

In the first embodiment, the magnetic flux generator is composed of a magnetic core, a coil, first and second magnetic plates, and the like, but the magnetic core and the magnetic plate are formed of silicon steel plate, permalloy, or the like.
Considering the frequency of the alternating magnetic field, use a laminated plate if the eddy current loss is not negligible.

In the embodiment of the present invention shown in FIGS. 2 and 3, between adjacent sides of the frame cells 21, 22 and the like, magnetic fluxes in opposite directions are applied to the conductor frame 1 respectively.
3 to supply current to the coil group. In this method, the current may be controlled for each individual coil, or the coils may be connected in series in the vertical and horizontal directions to supply the current collectively.

In FIG. 3, the magnetic flux flows downward from the magnetic core 27, flows into the magnetic cores 23 and 2b adjacent to each other via the magnetic plate 34, and further flows through the first magnetic plate 31. FIG. 4 shows a state in which the magnetic flux flows back to the magnetic core 27. Numeral 36 indicates the flow of the magnetic flux, and numeral 37 indicates an arrow indicating the direction of the magnetic flux. When the magnetic flux is driven by the magnetic cores 27 and 29, the second magnetic plate 32 becomes a part of the magnetic circuit instead of the first magnetic plate 31.

Apart from the above-described flow of magnetic flux, the first and second magnetic plates 31, 31 are provided between the magnetic cores 27 and 25.
There is also a possibility that magnetic flux flows through the intermediary 32. Such a path deteriorates the efficiency of magnetic flux generation, and if generated at random, it becomes noise when detecting a short circuit. In order to avoid these obstacles, the gap between the magnetic cores adjacent at the corner, for example, the gap between the magnetic cores 25 and 27 is increased, or the gap between the first and second magnetic bodies is increased so that the two overlap. There are measures to make the parts as small as possible. In the present embodiment, a copper plate 33 is further disposed between the first and second magnetic plates 31 and 32 to reduce a magnetic short circuit. That is, in the short circuit detection device according to the present invention, the amount of induced current to which an alternating magnetic flux or a pulsed magnetic flux is applied is monitored. The non-magnetic conductor has no effect on the DC magnetic flux, but has the property of causing an eddy current when the alternating magnetic flux tries to pass, increasing the impedance to the alternating magnetic flux and making it difficult to pass the magnetic flux. If the magnetic cores or the magnetic bodies have different potentials, a current flows in an unexpected direction and adversely affects the measurement. However, by making the conductors electrically the same potential, those concerns can be reduced. In this embodiment, a copper plate 33 is disposed between the first and second magnetic plates 31 and 32 in consideration of the above.

FIG. 4 is a view for further explaining the principle of operation of the present invention, and shows a conductor frame, lead wires, a part of a magnetic plate, and an ammeter for current detecting means.
Referring to FIG.
43 are connected, and lead wires 4
7, an ammeter 46 is connected. Also number 44
Indicates a magnetic plate, and numeral 45 indicates a cutout portion provided on the magnetic plate 45 for the lead wire 47. The magnetic fluxes 48 and 4a are applied to the conductor frame 41 in a substantially vertical direction by the short circuit detection device shown in FIGS. 2 and 3 and circulate through the magnetic plate 44. Since there is a cut-out portion as indicated by numeral 45, the magnetic flux flows as indicated by numerals 49 and 4b. On the other hand, the ammeter 46 includes the lead wire 47, the lead wires 42 and 43, and the conductor frame 4.
1 form a closed circuit, and the alternating magnetic fluxes 48 and 4a interlinking with the closed circuit do not interlink with the closed circuit again as indicated by numbers 49 and 4b, so that current is induced in the closed circuit. . If there is a short-circuit portion between the lead wires 42 and 43, a current flows in the short-circuit portion and it is difficult to reach the ammeter, and the presence or absence of the short-circuit portion can be detected.

A second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a plan view of the magnetic flux generating unit, and FIG. 6 is a side view thereof. In the figure, each frame cell constituted by the conductor frame 13 has one magnetic flux generating portion in which a coil is wound around a C-shaped magnetic core, and the direction of the magnetic core is orthogonal to each adjacent frame cell. Deploy. That is, a coil 52 is wound around a C-shaped magnetic core 51, and the ends of the magnetic core 51 are arranged so as to be in the form of a conductor frame constituting opposing sides of a frame cell. Are similarly arranged so that the directions of the magnetic cores are orthogonal to each other, so that magnetic flux can be supplied to each of the four sides of the frame cell. Number 55
Indicates a conductor arranged between adjacent magnetic cores.

Although the principle and operation are the same as those of the first embodiment, the description thereof is omitted. However, the conductor 55 prevents magnetic fluxes generated from both ends of the magnetic cores 51 and 53 from being short-circuited through the magnetic cores adjacent at right angles. In addition, the magnetic core group acts to keep the same potential. The operation is the same as that of the conductor plate in the first embodiment.

[0021]

As described above, according to the present invention, according to the present invention, a current is induced by magnetically coupling to a conductive frame for plating to which a lead wiring is connected, and the other end of the lead wiring is formed. A short circuit between the lead wires can be easily detected depending on whether or not a current flows between them. Further, the magnetic flux generating part according to the present invention has a simple structure and can be easily mass-produced. In addition, even when inspecting a short circuit, all the frame cells are selected at the same time, or an arbitrary frame cell is selected to induce a current in the conductor frame to cause a short circuit. It is possible to construct a flexible system at the time of implementation, for example, it is possible to investigate a part.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a circuit board to be inspected by the present invention;

FIG. 2 is a plan view of a magnetic flux generating unit according to the first embodiment of the present invention.

FIG. 3 is a side view of a magnetic flux generation unit according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining the operation principle of the present invention.

FIG. 5 is a plan view of a magnetic flux generator according to a second embodiment of the present invention.

FIG. 6 is a perspective view of a magnetic core and a coil according to a second embodiment of the present invention.

[Explanation of symbols]

11 ... contact part, 12 ...
・ Lead wiring, 13 ・ ・ ・ Conductor frame,
14 ... enlarged part, 15 ... cutting removal area,
16 lead wiring, 17 lead wiring, 18 short circuit part 21, 22, frame cell, 23, 25, 27, 2
9, 2b ... magnetic core, 24, 26, 28, 2a, 2c
..Coil 31 ... first magnetic plate, 32 ..
.Second magnetic plate, 33... Copper plate,
34 ... magnetic plate, 35 ... circuit board,
36 ... magnetic flux, 37 ... arrow indicating the direction of magnetic flux 41 ... conductor frame,
42, 43 lead wiring, 44 magnetic plate, 45 cutout of magnetic plate, 46 ammeter,
47 Lead wire, 48, 4a Magnetic flux interlinked with the conductor frame, 49, 4b Magnetic flux 51, 52 Magnetic core, 52, 5
4. Coil, 55 ... conductor

Claims (4)

[Claims] An apparatus for detecting a short circuit on a circuit board having a plurality of frame cells having a plurality of lead wires connected to a conductor frame as a common conductor, a magnetic flux generator and a magnetic material for magnetic flux recirculation. A magnetic core and a coil for driving the magnetic core, which are disposed on the conductor frame on each of the four sides of the frame cell, and wherein the magnetic plate is a circuit board. A magnetic material having a cut-out portion for connection to a lead wiring disposed at the center of the frame cell with respect to the magnetic flux generation portion with respect to the magnetic flux generating portion. Composed of
A short circuit circuit for a circuit board, wherein an alternating magnetic field or a pulse magnetic field is generated by the coil and linked to the conductor frame to determine the presence or absence of a short circuit between the lead wires from a current induced between the lead wires. Detector 2. The circuit board short-circuit detection device according to claim 1, wherein an end of the magnetic core disposed on each side of the two-dimensionally arranged frame cells on a side not facing the circuit board. A magnetic circuit formed by connecting the first and second magnetic plates on each of the vertically and horizontally opposed sides of the frame cell, wherein each magnetic core has a coil. Short circuit detection device 3. The circuit board short circuit detecting device according to claim 1, wherein the C-shaped magnetic core having the coil wound thereon is two-dimensionally arranged so that the directions of the magnetic cores are mutually orthogonal between adjacent frame cells. Circuit board short-circuit detection device, wherein one is arranged in each of a plurality of frame cells arranged in a series 4. A short circuit detecting apparatus for a circuit board according to claim 2, wherein a conductive material is provided between magnetic cores on adjacent sides of the frame cell and between magnetic circuits formed by the magnetic cores. A circuit board short-circuit detection device characterized in that it is arranged in a gap to make it difficult for the alternating magnetic flux to pass therethrough and at the same time to reduce the measurement obstacle as the same potential.