JP2000138438A - Inspecting method for printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily confirm, with sure, omission of printing an overcoat or miss-printing such as print slippage, etc. SOLUTION: A specified coat pattern of a resin coat 7 allows a part of a circuit pattern 5 to be exposed, and a hole part 7a for forming an overcoat confirming electrode 5c is provided. A specified coat pattern of an overcoat 13 comprises a closure pattern 13c which closes the hole part 7a. When a current is made to flow between one probe P0 positioned above the overcoat confirming electrode 5c and the other probe P5 contacting an electrode 5d which is electrically connected to the overcoat confirming electrode 5c, the formation of the overcoat 13 is confirmed based on the presence of current between one probe P0 and the other probe P5.

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 circuit board, and more particularly to a method for inspecting a printing error of an overcoat made of an insulating resin.

[0002]

2. Description of the Related Art A circuit pattern formed on a printed circuit board is used for the purpose of preventing the adhesion of solder except for electrodes,
In order to prevent disconnection (protection purpose) or to prevent contact with the terminals of the mounted electronic components, use a resin coat made of an insulating resin with a predetermined coat pattern (for example, an ultraviolet-curable insulating resin, etc.). Covered. When a jumper wire or through-hole conductive part is formed on the circuit pattern, an overcoat made of an insulating resin of a predetermined coat pattern is further formed on the resin coat so as to cover the surface of the jumper wire or the through-hole conductive part. are doing. This overcoat is formed by screen printing. However, in the case of mass production, printing errors such as forgetting to print or printing misregistration occur during overcoat printing. Conventionally, these printing errors have been visually confirmed by an operator.

[0003]

However, it is practically impossible for an operator to check all of the printed circuit boards to be manufactured, and the printed circuit board in which the above-described printing error has occurred is shipped as it is. There are cases.

It is an object of the present invention to provide a method for inspecting a printed circuit board, which can easily and reliably confirm a printing error such as forgetting to print an overcoat or a printing deviation.

[0005]

According to the present invention, a circuit pattern is formed on a surface of an insulating substrate, a resin coat made of an insulating resin having a predetermined coat pattern is formed on the circuit pattern, and a predetermined coat is formed on the resin coat. It is an object of the present invention to improve a method of inspecting a printed circuit board on which an overcoat made of an insulating resin of a pattern is further formed. In the present invention, a hole pattern for exposing a part of a circuit pattern to a predetermined resin coat pattern to form an overcoat confirmation electrode is provided, and the predetermined coat pattern of the overcoat closes the hole. Is provided. When an overcoat is formed with the printed circuit board in a fixed position, one probe comes into contact with the overcoat obstruction pattern, and the other probe electrically contacts the overcoat confirmation electrode of the circuit pattern. An overcoat check measuring device including a pair of check probes that come into contact with a reference electrode included in a wiring portion of a circuit pattern that is continuously connected is prepared. The reference electrode may be an electrode provided exclusively for confirmation, but may be a soldering electrode included in the wiring portion or a contact portion of a switch. Then, with the pair of confirmation probes arranged at the measurement position, the presence or absence of the formation of the overcoat is electrically inspected based on whether or not a current flows between one probe and the other probe.

In the inspection method of the present invention, a hole for exposing a part of the circuit pattern to a predetermined resin coating pattern to form an overcoat confirming electrode is provided.
A closing pattern for closing the hole is provided in a predetermined coat pattern of the overcoat. Therefore, the formation state of the overcoat can be confirmed by checking the formation state of the closed pattern on the overcoat confirmation electrode. According to the present invention, when the overcoat is formed, one of the pair of confirmation probes comes into contact with the closing pattern of the overcoat, and the other probe contacts the reference electrode of the circuit pattern to form a pair of confirmation probes. No current flows between the probes. On the other hand, if the overcoat is not formed due to a printing error or the like, the pair of check probes comes into contact with both the overcoat check electrode and the reference electrode of the circuit pattern. Current flows between the probes. Thus, the presence or absence of the formation of the overcoat can be easily and reliably confirmed by checking whether a current flows between one probe and the other probe.
As a result, it is possible to prevent the printed circuit board on which the overcoat printing is forgotten from being shipped as it is.

[0007] However, even if the presence of the overcoat can be confirmed electrically, unless there is a very large printing deviation,
It is not possible to inspect the printing deviation of the overcoat. In order to check the print misalignment in a specific direction, the hole and blockage pattern should be changed by using one probe for the overcoat confirmation electrode when the overcoat displacement dimension in the specific direction exceeds the allowable displacement dimension. Each is formed in a shape that is exposed to a size greater than or equal to the size that can be contacted. One probe is arranged at a position facing a part of the overcoat confirmation electrode. Then, in a state where the pair of confirmation probes is arranged at the measurement position, whether or not the overcoat is formed and the displacement of the overcoat are electrically determined based on whether or not a current flows between the one probe and the other probe. inspect. Here, the allowable deviation dimension is an arbitrary value set according to the purpose of use of the printed circuit board and the like.

By employing such an inspection method, when the overcoat is formed without causing a printing shift in a specific direction, one of the pair of confirmation probes comes into contact with the overcoat blockage pattern. Thus, no current flows between the pair of confirmation probes. On the other hand, if the displacement of the overcoat in the specific direction exceeds the allowable displacement and causes a printing displacement, one probe comes into contact with a part of the overcoat confirmation electrode.
Therefore, a current flows between the pair of confirmation probes. Thus, the displacement of the overcoat can be easily and reliably confirmed based on whether or not a current flows between one probe and the other probe. As a result, it is possible to prevent the printed circuit board in which the overcoat has exceeded the allowable shift dimension in the specific direction and has caused the print shift from being shipped as it is.

[0009] It is difficult to accurately confirm the presence or absence of a print shift in the overcoat in the detection of a print shift in the overcoat only in a specific direction. Therefore, in order to almost surely detect the print shift, it is necessary to confirm the print shift in the four orthogonal directions (the above-described specific direction, the direction opposite to the specific direction, and the two directions orthogonal to the specific direction and the opposite direction). preferable. If the printing displacement in the four orthogonal directions can be confirmed in this manner, the printing displacement can be almost surely detected with as few probes as possible. As described above, in order to confirm the print misalignment in the four orthogonal directions, it is necessary to determine whether the overcoat misalignment dimension in the direction opposite to the specific direction exceeds the allowable misalignment dimension and to determine whether the overcoat misalignment is in the specific direction and the opposite direction. A hole and a closing pattern are formed in such a shape as to expose another part of the overcoat confirming electrode even when the deviation of the overcoat in one direction exceeds the allowable deviation. Further, three probes that can come into contact with another part of the overcoat confirmation electrode when the overcoat is formed in the opposite direction and in the two directions with a deviation larger than the allowable deviation dimension are further prepared. Then, the displacement of one of the probes and the three probes and the overcoat may be electrically inspected. If such an inspection method is adopted, orthogonal 4
One of the probes located on the overcoat confirmation electrode is one of the overcoat confirmation electrodes when the overcoat displacement dimension in any one of the directions Will come in contact. Therefore, a current flows between the pair of confirmation probes. This makes it possible to easily and surely confirm the displacement of the overcoat in four orthogonal directions depending on whether or not a current flows between the probes. As a result, it is possible to prevent a printed circuit board in which the overcoat has exceeded the allowable shift dimension in the four orthogonal directions and has caused a print shift from being shipped as it is.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1A is a plan view of a main part of a printed circuit board to be inspected by a method according to an embodiment of the present invention, and FIG.
It is a B sectional view. As shown in each figure, the printed circuit board 1 is provided with predetermined front side circuit patterns 5 and back side circuit patterns 5 'made of copper foil or the like on both surfaces of an insulating substrate 3 such as a glass epoxy substrate. Then, a predetermined coat pattern covering the front-side circuit pattern 5 is exposed so as to expose the jumper wire electrode 5a, the front-side through-hole land 5b, the overcoat confirmation electrode 5c, and the soldering electrode 5d used as a reference electrode. The surface side resin coat 7 made of insulating resin is formed. On the back side, a back side resin coat 7 'is formed to cover the back side circuit pattern 5' so as to expose the back side through-hole land portion 5b '. In addition, FIG.
In (B), the resin coats 7 and 7 ′ are formed so as to cover almost the entire surfaces of both surfaces of the insulating substrate 3 except for the portions to be exposed such as electrodes. The jumper wire electrode 5a is connected to a jumper wire 9 extending from the jumper wire electrode 5a on the front side resin coat 7 in a predetermined direction. Also, the through-hole lands 5b and 5b '
Through-holes 3a penetrating through-hole lands 5b, 5b 'and insulating substrate 3 are formed. And
In the through hole 3a, a through hole land portion 5b,
A through-hole conductive portion 11 for electrically connecting 5b 'is formed. The overcoat confirmation electrode 5c is formed in a substantially square shape. The soldering electrode 5d is used, for example, to solder one electrode of a chip resistor. Therefore, the predetermined coat pattern of the front-side resin coat 7 includes rectangular holes 7a and 7b for forming the overcoat confirmation electrode 5c and the electrode 5d.

On the resin coats 7, 7 ', an overcoat 13 and an overcoat 13' made of an insulating resin made of an epoxy resin or the like having a predetermined coat pattern.
Are further formed. The predetermined coat pattern of the front side overcoat 13 includes overcoat portions 13A, 13B and 13C that respectively cover the jumper wire 9, the exposed portion on the front side of the through-hole conductive portion 11, and the overcoat confirmation electrode 5c. I have. Also, the back side overcoat 1
The predetermined coat pattern 3 ′ includes an overcoat portion 13B ′ that covers an exposed portion on the back surface side of the through-hole conductive portion 11. These overcoat portions 13A are formed simultaneously by the same process.

In this example, the overcoat 13C forms a closing pattern. Therefore, the overcoat section 1
3C is called an occlusion pattern. The closing pattern 13C is formed by a square having a size larger than the overcoat confirmation electrode 5c, and completely covers the overcoat confirmation electrode 5c when the front side overcoat 13 is formed at an appropriate position. It has a shape.

In the drawings, P0 and P5 are probes of a printing error measuring device used in the inspection method of the present embodiment.
This printing error measuring instrument is an overcoat checking measuring instrument for checking whether or not the front side overcoat 13 is formed. This measuring instrument moves the probes P0 and P5 in the longitudinal direction so that the tips of the probes P0 and P5 can be brought into contact with each part of the printed circuit board 1 in a state where the printed circuit board 1 is positioned at a fixed position. (A direction perpendicular to the substrate surface of the insulating substrate 3). The probe P0 is one of the probes P0 and P5. One probe P0 is disposed so as to be located substantially on the center of the overcoat confirmation electrode 5c and the closing pattern 13C with the printed circuit board positioned at a fixed position.

Of the probes P0 and P5, the probe P5
Is the other probe. The other probe P5 contacts the electrode 5d included in the wiring portion of the circuit pattern 5 electrically connected to the overcoat confirmation electrode 5c of the circuit pattern 5 in a state where the printed circuit board 1 is positioned at a fixed position. Are located in

As shown in FIGS. 1A and 1B, when the overcoat 13 is formed, one probe P0 comes into contact with the closing pattern 13C of the overcoat 13 and the other probe P5 Is the electrode 5 of the circuit pattern 5
d, and the both are insulated by the closing pattern 13C. Therefore, when a current flows between one probe P0 and the other probe P5, no current flows between the two, and it can be confirmed that the overcoat 13 is formed.

On the other hand, as shown in FIG. 2, when the overcoat 13 is not formed due to a printing error or the like, both the one probe P0 and the other probe P5 come into contact with the circuit pattern 5. Will be. Thereby, a current flows between one probe P0 and the other probe P5, and it can be confirmed that the overcoat 13 is not formed.

FIG. 3A is a plan view of a main portion of a printed circuit board to be inspected by a method according to another embodiment of the present invention, and FIG. FIG. 3C is a cross-sectional view taken along line B, and FIG. 3C is a cross-sectional view taken along line CC in FIG. In this example, only the structure of the probe is different from that of the above-described embodiment, and the printed circuit board has the same structure as the printed circuit board shown in FIGS. In this example,
Holes 7a and closing pattern 13 of front side resin coat 7
C is the displacement dimension of the overcoat 13 is the allowable displacement dimension PL.
Are formed in such a shape that a part of the overcoat confirmation electrode 5c is exposed to a size larger than a size capable of contacting any of confirmation probes P1 to P4 described later. Here, the allowable deviation dimension PL is an arbitrary value set according to the purpose of use of the printed circuit board 1 or the like. In the drawings, P1 to P5 are probes of a printing error measuring instrument used in the inspection method of the present embodiment. This printing error measuring instrument has a function of an overcoat checking measuring instrument for checking whether or not the front side overcoat 13 is formed, and a function of an overcoat printing shift detecting measuring apparatus for detecting a printing shift of the front side overcoat 13. This is a measuring instrument that also has.
This measuring instrument is configured to move the probes P1 to P5 in the longitudinal direction so that the tips of the probes P1 to P5 can be brought into contact with each part of the printed circuit board 1 in a state where the printed circuit board 1 is positioned at a fixed position. (A direction perpendicular to the substrate surface of the insulating substrate 3). Of the probes P1 to P5, the probes P1 to P5
4 is a confirmation probe. Confirmation probes P1, P2
Is the electrode 5c for checking overcoat in the horizontal direction with respect to the drawing, with the printed circuit board 1 positioned at a fixed position.
Are arranged so as to be respectively located on the edges of the. The confirmation probes P3 and P4 are the confirmation probes P
1 and P2 are arranged so as to be located on the edges of the overcoat confirmation electrode 5c in two directions (up and down directions in the drawing) orthogonal to the direction in which the P1 and P2 are arranged.

Of the probes P1 to P5, the probe P5
Is a reference probe. The reference probe P5 is arranged at a position where it contacts the electrode 5d of the circuit pattern 5 which is electrically connected to the overcoat confirmation electrode 5c of the circuit pattern 5 with the printed circuit board positioned at a fixed position. In this example, any one of the confirmation probes P1 to P4 constitutes one probe, and the remaining three confirmation probes constitute three probes that can come into contact with another part of the overcoat confirmation electrode 5c. are doing. The reference probe P5 constitutes the other probe.

The confirmation probes P1 to P4 are shown in FIG.
As shown in (C), when the overcoat 13 is formed, at least one (one probe) of the confirmation probes P1 to P4 comes into contact with the closing pattern 13C of the overcoat 13 and the reference probe (The other probe)
P5 is in contact with the electrode 5d of the circuit pattern 5, and the both are insulated by the closing pattern 13C. Therefore, when a current flows between the confirmation probes P1 to P4 and the reference probe P5, an overcurrent occurs because no current flows between at least one of the confirmation probes P1 to P4 and the reference probe P5. It can be confirmed that the coat 13 is formed.

On the other hand, as shown in FIG. 4, when the overcoat 13 is not formed due to a printing error or the like, the confirmation probes P1 to P4 and the reference probe P5
Will come into contact with the circuit pattern 5. As a result, a current flows between each of the confirmation probes P1 to P4 and the reference probe P5, and the overcoat 13
It can be confirmed that no is formed.

FIGS. 5A and 5B show printing in the vicinity of the closing pattern 13C when the displacement of the overcoat 13 in the right direction toward the drawing slightly exceeds the allowable displacement PL due to a printing error or the like. It is the top view and sectional drawing of a circuit board. As described above, the hole 7a and the closing pattern 13C of the front side resin coat 7 are
When the displacement dimension of the electrode exceeds the allowable displacement dimension PL, a part of the overcoat confirmation electrode 5c is
Each of them is formed in a shape that is exposed to a size larger than a size capable of contacting any one of P4. Therefore, when the overcoat 13 causes printing misalignment as described above, the confirmation probe P
1 comes into contact with a part of the overcoat confirmation electrode 5c. Therefore, a current flows between the confirmation probe P1 and the reference probe P5, and the confirmation probes P2 to P2.
No current flows between each probe of P4 and the reference probe P5. Thereby, it can be confirmed that the overcoat 13 has been shifted in the rightward direction in the drawing beyond the allowable shift dimension PL. Note that, in this example, an example is shown in which the overcoat 13 is printed shifted to the right toward the drawing, but the overcoat 13 is printed beyond the allowable shift dimension PL to the left as viewed in the drawing. In this case, the checking probe P2 comes into contact with another part of the overcoat checking electrode 5c. Therefore, a current flows between the confirmation probe P2 and the reference probe P5, and each of the confirmation probes P1, P3, and P4 and the reference probe P5.
5 does not flow. Thereby, it can be confirmed that the overcoat 13 is misprinted in the leftward direction in the drawing beyond the allowable misalignment dimension PL. When the overcoat 13 is printed on the upper side of the drawing beyond the allowable deviation dimension PL, the confirmation probe P4 comes into contact with another part of the overcoat confirmation electrode 5c. Therefore, a current flows between the confirmation probe P4 and the reference probe P5, and the confirmation probes P1 to P3
No current flows between the respective probes and the reference probe P5. Thereby, it can be confirmed that the overcoat 13 is misaligned in printing in the upward direction in the drawing beyond the allowable misalignment dimension PL. When the overcoat 13 is printed below the allowable deviation dimension PL below the drawing, the checking probe P3 comes into contact with another part of the overcoat checking electrode 5c. . Therefore, current flows between the checking probe P3 and the reference probe P5, and no current flows between each of the checking probes P1, P2, and P4 and the reference probe P5. Thereby, it can be confirmed that the overcoat 13 is misprinted in the lower direction toward the drawing beyond the allowable misalignment dimension PL.

In the present embodiment, the hole 7a and the closing pattern 13C of the front side resin coat 7 are formed in a substantially square shape.
When the overcoat displacement dimension in the specific direction exceeds the permissible displacement dimension, a portion of the overcoat confirmation electrode may be formed in a shape that is exposed to a size that can be in contact with the confirmation probe or more. It can be formed into various shapes such as a circle.

[0023]

According to the inspection method of the present invention, a hole for exposing a part of the circuit pattern to the predetermined coat pattern of the resin coat to form an electrode for confirming the overcoat is provided. If a coat pattern is provided with a closing pattern that closes the hole, and if an overcoat is formed, one probe that contacts the closing pattern of the overcoat and a reference electrode included in the wiring part of the circuit pattern are provided. An overcoat check measuring device equipped with the other probe to be contacted was prepared, and the presence or absence of the overcoat was checked by checking whether an electric current flows between the pair of check probes. Can be easily and reliably checked. Further, according to the present invention, it is possible to prevent a printed circuit board in which overprinting is forgotten from being printed and a printed circuit board in which overcoating is out of print beyond the allowable deviation dimension from being shipped as they are. it can.

[Brief description of the drawings]

FIG. 1A is a plan view of a printed circuit board used in an inspection method according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line BB of FIG. 1A.

FIG. 2 is a cross-sectional view of the printed circuit board when an overcoat is not formed in the inspection method according to the embodiment of the present invention.

FIG. 3A is a plan view of a printed circuit board used in an inspection method according to another embodiment of the present invention, and FIG.
FIG. 3C is a sectional view taken along line BB of FIG.
It is a CC sectional view taken on the line of (A).

FIG. 4 shows an inspection method according to another embodiment of the present invention.
FIG. 4 is a cross-sectional view of the printed circuit board when an overcoat is not formed.

FIGS. 5A and 5B show an inspection method according to another embodiment of the present invention in a case where a deviation dimension of an overcoat in the right direction toward the drawing slightly exceeds an allowable deviation dimension; It is a top view and a sectional view of a printed circuit board in the neighborhood of an obstruction pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board 3 Insulating board 5, 5 'Circuit pattern 5c Overcoat confirmation electrode 7, 7' Resin coat 7a Hole 13, 13 'Overcoat 13C Closure pattern P1-P4 Confirmation probe P5 Reference probe

Claims (3)

[Claims] 1. A circuit pattern is formed on the surface of an insulating substrate, a resin coat made of an insulating resin having a predetermined coat pattern is formed on the circuit pattern, and a resin coat made of an insulating resin having a predetermined coat pattern is formed on the resin coat. A method for inspecting a printed circuit board further comprising an overcoat, wherein a hole for exposing a part of the circuit pattern to the predetermined coat pattern of the resin coat to form an overcoat confirmation electrode. Providing a closing pattern for closing the hole in the predetermined coat pattern of the overcoat, with the printed circuit board positioned at a fixed position,
When the overcoat is formed, one probe is in contact with the closing pattern of the overcoat, and the other probe is electrically connected to the overcoat confirmation electrode of the circuit pattern. Prepare an overcoat check measuring device provided with a pair of check probes that are in contact with the reference electrode included in the portion, and in a state where the pair of check probes are arranged at the measurement position, the one probe and the other Wherein the presence or absence of the overcoat is electrically inspected based on whether a current flows between the probes. 2. A part of the overcoat confirming electrode is in contact with the one probe when a deviation dimension of the overcoat in a specific direction exceeds an allowable deviation dimension. Each of the probes was formed in a shape that was exposed to a size larger than a possible size, the one probe was arranged at a position facing the part of the overcoat confirmation electrode, and the pair of confirmation probes was arranged at a measurement position. 2. In the state, whether or not the overcoat is formed and a position shift of the overcoat are electrically inspected based on whether or not a current flows between the one probe and the other probe. 3. The method for inspecting a printed circuit board according to claim 1. 3. The method according to claim 1, wherein the hole and the closing pattern are perpendicular to the specific direction and the opposite direction when a deviation dimension of the overcoat in a direction opposite to the specific direction exceeds an allowable deviation dimension. The overcoat is formed in a shape that exposes another part of the overcoat confirmation electrode even when a deviation dimension of the overcoat in two directions exceeds an allowable deviation dimension. Three probes that can come into contact with the other part of the overcoat confirming electrode when the two probes are formed so as to be shifted from the allowable shift dimension in the two directions, the one probe and the three probes; 3. The method for inspecting a printed circuit board according to claim 2, further comprising: electrically inspecting a positional shift between the overcoat and the overcoat.