JPH05107194A - Inspecting apparatus for printed wiring board - Google Patents

Abstract

PURPOSE:To enable uniform inspection while achieving a reduction in labor by detecting how a conductive paint fills a through hole with a CCD camera from the opposite side to the side of filling to eliminate the need for visual inspection with a possible automatic inspection. CONSTITUTION:A squeegee 2 is kept running at a specified angle on a substrate 1 to make a conductive paint 3 fill a through hole 4. A detection means 6 has a CCD camera 9 so arranged on the rear of the substrate 1 to face the hole 4 which the paint 3 fills. So, a digital signal of an image of a peripheral part of the hole 4 is displayed visible on a video monitor while the diameter of the paint 3 extruded to the rear of the hole 4 is detected and the resulting detection signal is outputted to a judging means 7. The means 7 compares a data pertaining to the diameter of a land formed at the hole 4 and in the perimeter thereof stored therein with the diameter of the paint 3 inputted from the means 6 to judge the propriety of the filling. When receiving a judging signal of the poor filling level, a control means 8 increases or decreases in the angle of inclination of the squeegee 2 to correct the filling level of the paint 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board inspecting apparatus for inspecting a filling amount of a conductive paint when the through holes of the substrate are filled with the conductive paint so that circuits on both front and back surfaces of the substrate are electrically connected.

[0002]

2. Description of the Related Art In the manufacture of printed wiring boards, circuits are formed on both front and back surfaces of a substrate, and the circuits on both front and back surfaces are electrically connected to each other. In order to electrically connect the circuits on both the front and back sides, it is necessary to form a through hole in the substrate and fill the through hole with a conductive paint. For this reason, a squeegee is run on one surface of the substrate through a screen, and conductive paint is filled into the through-holes that require conduction by running the squeegee.

By the way, when the conductive paint is filled into the through hole, the filling amount must be appropriate. This is because if the filling amount is too small, the circuits on both sides of the substrate cannot be conducted, while if the filling amount is too large, the circuits on both sides of the substrate are short-circuited by the conductive paint. Therefore, it is necessary to inspect whether the filling of the conductive paint is appropriate,
Conventionally, the operator has visually inspected the filled state of the conductive paint in the through holes by pulling out the manufactured printed wiring boards for every predetermined number.

[0004]

However, in the conventional visual inspection by the operator, it is difficult to reduce the labor for manufacturing the printed wiring board because the operator is required exclusively. Further, in the visual inspection, since the inspection standard differs depending on the operator, it is not possible to perform a uniform inspection, so that inspection errors frequently occur.

The present invention has been made in consideration of the above-mentioned conventional problems, and it is possible to automatically detect the filling state of the conductive paint in the through hole to reduce the labor and to perform an accurate inspection. It is an object of the present invention to provide a possible printed wiring board inspection device.

[0006]

In order to achieve the above object, the present invention relates to a method of manufacturing a printed wiring board for filling a through hole formed in a substrate with a conductive paint to conduct circuits on both sides of the substrate. A CCD camera for detecting the filling state of the conductive paint after filling the through hole is arranged so as to face the substrate surface opposite to the filling surface.

[0007]

In the above construction, since the detecting means detects the filling of the conductive paint in the through hole with the CCD camera, it is not necessary for the operator to pull out the printed wiring board and visually check it. For this reason, an operator for inspection is not required, labor can be reduced, and uniform inspection can be performed to eliminate inspection errors.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an overall configuration to which the present invention is applied.
A screen (not shown) is stretched on the substrate 1 on which circuits are formed on both front and back surfaces, and the squeegee 2 runs on this screen, whereby the conductive paint 3 is printed on a predetermined portion of the substrate 1.

The present invention is applied to the step of filling the conductive paint 3 into the through holes 4 formed in the substrate 1. That is, as shown in FIG. 2, through holes 4 are formed in the substrate 1 in a penetrating manner by a punch, a drill or the like, and lands 5 for circuit connection are formed on both sides of the substrate 1 around the through holes 4. Are formed.

The squeegee 2 runs in the direction of arrow A while maintaining a predetermined angle α with respect to the substrate 1, so that the conductive paint 3 is filled in the through holes 4. As a result, as shown in FIG. 3, the conductive paint 3 conducts the lands 5 on both the front and back surfaces of the substrate 1 to electrically connect the circuits formed on both the front and back surfaces of the substrate 1.

In order to fill the conductive paint 3 in the through hole 4 as described above, in this embodiment, as shown in FIG. 1, a detecting means 6, a judging means 7 and a controlling means 8 are provided. The detection means 7 detects the filling amount of the conductive paint 3 in the through hole 4. The detection means 7 detects the filling amount of the conductive paint 3 from the substrate surface opposite to the filling, that is, the back surface of the substrate 1. Therefore, the detection means 7 has a CCD camera 9 provided so as to face the surface of the substrate opposite to the side where the conductive paint is filled, and a video monitor (not shown) to which a video image from the CCD camera 9 is input. Have The CCD camera 9 is arranged on the back side of the substrate 1 so as to face the through hole 4 filled with the conductive paint 3. The video image of the peripheral portion of the through hole 4 is digitized and the video signal is output to a video monitor. To do. The video monitor visually displays the input video signal on a display (not shown), detects the diameter of the conductive paint extruded from the through hole 4 to the back side of the substrate 1, and outputs the detection signal to the determination means 7. .. Note that C
The CD camera 9 may be a camera that binarizes a video image and outputs it as a monochrome image, or a camera that outputs it as a color image.

The detecting means 6 as described above is provided in the through hole 4
Since the video image of the conductive paint 3 extruded from the backside of the substrate 1 is visually displayed on the display, the operator visually checks the video image of the conductive paint 3 to check the filling amount of the conductive paint 3 into the through hole 4. The quality of can be determined. That is, the conductive paint 3 extruded from the through hole 4 to the back side of the substrate 1 covers the inner peripheral side of the land 5 around the through hole 4 on the back surface of the substrate 1, and the conductive paint 3 is the outer periphery of the land 5. If it does not extend to the side, it can be determined that the filling amount is good. on the other hand,
When the conductive paint 3 does not cover the inner peripheral side of the land 5 on the back surface of the substrate 1, the lands 5 on both the front and back surfaces of the substrate 1 are not electrically connected, and therefore it can be determined as defective, and the conductive paint 3 forms the outer peripheral surface of the land 5. If it extends beyond the range, it can be determined that the circuit is defective because the circuit is short-circuited by the conductive paint 3.

Therefore, since it is not necessary to turn over the substrate 1 and visually inspect it after the conductive paint 3 is filled, the inspection can be performed easily and surely. In addition, conductive paint 3
The quality of the filling amount of can be checked at the same time as the filling, so that it is possible to promptly take measures such as filling correction.
It is possible to speed up the production of the printed wiring board and prevent the occurrence of defective products. Furthermore, since it is possible to inspect all manufactured printed wiring boards, it is possible to improve the quality as a whole.

FIG. 3 shows another mode for detecting the quality of the conductive paint filling by the CCD camera 9. In this case, CCD
The camera 9 detects the diameter D of the conductive paint 3 extruded from the through hole 4 to the back surface of the substrate 1. Detected conductive paint 3
The diameter D is sent to the detection means 6 and output from the detection means 6 to the determination means 7 (see FIG. 1). The determination means 7 stores data regarding the diameter of the through hole 4 filled with the conductive paint 3 and data regarding the diameter of the land formed around the through hole 4, and the determination means 7 detects these reference values and detection. The diameter of the conductive paint input from the means 6 is compared.

In this comparison, the judging means 7 judges that the filling amount of the conductive paint 3 is good when (the diameter of the through hole + 0.1 mm) ≦ D ≦ (the diameter of the land). On the other hand, when the diameter D of the conductive paint 3 is smaller than the diameter of the through hole +0.1 mm, the filling amount is insufficient and the lands 5 on both the front and back surfaces of the substrate 1 are not electrically connected, so that it is determined to be defective and the diameter of the conductive paint 3 When D is larger than the diameter of the land 5, the filling amount is excessive,
It is determined to be defective because the circuit on the board is short-circuited. And
When the judging means 7 judges that it is defective, the judging means 7 outputs a judgment signal to the control means 8 (see FIG. 1).

Since the determination means 7 mechanically determines the quality of the filling amount on the basis of the detection signal from the detection means 6, visual inspection by an operator is not required and workability is improved. Further, it is possible to make a uniform quality determination and eliminate an error in determination by an operator, so that an accurate quality determination can be performed.

The control means 8 controls the operation of the entire printing machine for screen-printing the conductive paint 3 on the substrate. In this embodiment, the inclination angle α of the squeegee 2 traveling on the substrate 1 is controlled via the screen. To do. When the determination signal indicating that the filling amount is insufficient is input from the determination unit 7, the control unit 8 reduces the inclination angle α by inclining the squeegee toward the substrate 1. As a result, the pushing pressure by the squeegee 2 increases, so that the filling amount of the conductive paint increases and the insufficient filling is eliminated. On the other hand, the determination signal of the excess filling amount is the determination means 7.
The control means 8 raises the squeegee 2 to increase the inclination angle α. As a result, the pushing pressure by the squeegee 2 is reduced, so that the filling amount of the conductive paint is reduced and the overfilling is eliminated.

Therefore, by performing the control by the control means 8 as described above, at the same time as the filling of the conductive coating material 3 into the through hole 4, the underfilling or overfilling of the conductive coating material 3 is corrected and a certain filling amount can be secured. Therefore, the printed wiring board can be rapidly manufactured, and the amount of defective products is reduced. Further, since the appropriate amount of the conductive coating material 3 can be always filled in the through hole 4, the visual inspection after the filling is unnecessary, and the workability is improved.

[0019]

As described above, according to the present invention, since the filling state of the conductive paint in the through hole is detected from the side opposite to the filling side, automatic inspection is possible, and visual inspection by an operator is not required, which is labor intensive. It is possible to reduce the amount and to perform uniform inspection.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a step of filling conductive paint.

FIG. 3 is a cross-sectional view showing a filling inspection process.

[Explanation of symbols]

 1 Printed Circuit Board 2 Squeegee 3 Conductive Paint 4 Through Hole 5 Land 6 Detection Means 7 Judgment Means 8 Control Means 9 CCD Camera

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H05K 3/00 Q 6921-4E 3/40 K 6736-4E

Claims (1)

[Claims] 1. A manufacturing method of a printed wiring board in which a conductive paint is filled in a through hole formed in a board to conduct circuits on both front and back surfaces of the board, and a filling state of the conductive paint after filling the through hole is detected. The printed wiring board inspecting device is characterized in that the CCD camera is disposed so as to face the surface of the substrate opposite to the filling surface.