JPH071231B2 - Mounted printed circuit board automatic inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention sweeps a beam spot such as a laser beam that is narrowed down on a mounted printed circuit board, and is formed on the mounted printed circuit board by defective soldering. The present invention relates to a mounted printed circuit board automatic inspection device for detecting the presence or absence of a bridge.

[Conventional technology]

Conventionally, as a method of detecting a bridge due to poor soldering on a mounted printed circuit board, a head with a large number of pins arranged according to the component holes of the printed circuit board has been used, and the pins are used to solder the printed surface There is a contact inspection method in which a defective portion is detected by contacting with each other and the conduction state between the pins. However, in this method, it is necessary to prepare a head for each different type of printed circuit board, and the pin interval of the head is limited by the thickness of the pin. There is a problem that it is difficult to inspect a printed circuit board having a dense pattern such as a mounted printed circuit board.

In order to solve the above problems, a beam such as a laser beam is scanned to sweep the beam spot on the printed circuit board to be inspected, and the sputtered light (reflected light) of this beam spot is detected to create a bridge, etc. A non-contact type mounted printed circuit board automatic inspection device for performing the above inspection has been proposed by the present applicant and is disclosed in JP-A-61-76940.

[Problems to be solved by the invention]

FIG. 7 is a diagram showing an example of a solder joint portion of a chip component of a mounted printed circuit board, which is inspected by the non-contact type mounted printed circuit board automatic inspection apparatus as described above, and is shown in FIG. As described above, when a bridge is formed between the leads L ₁ and L _{2 of} the chip component T ₁ and the chip component T ₂ mounted on the printed circuit board P, the sputtered light S of the laser beam B is detected. as can be detected in the bridge, for example, it is shown in FIG. (B), the chip component T ₂
When the lead L _{2 of} is bent and soldered, the sputter light of the laser beam B is generated by the lead L ₂ even though the bridge is not formed, and the sputter light is detected and the bridge is erroneously detected. May be

[Means for solving problems]

In order to solve the above-mentioned problems and to detect a bridge, the present invention irradiates a printed circuit board to be inspected with a narrowly focused beam, and the reflected light is reflected in a direction opposite to the beam irradiation direction. In the mounted printed circuit board automatic inspection device that detects the reflected light and performs the bridge inspection of the printed circuit board,
A light receiving portion having an opening for passing the beam vertically toward the printed circuit board to be inspected, covering a beam irradiation surface of the printed circuit board to be inspected, and having a light receiving surface surrounding the beam to be irradiated; A means for sweeping a plurality of times in a direction intersecting a line segment connecting a component mounting portion (hole) to which the electronic component is soldered, and a case where all the reflected light of the number of times of the sweep is received by the light receiving portion And a processing device for determining that there is a bridge.

[Action]

When sputtered light is detected caused by a lead L ₂ by sweeping the beam spot in the first sweep position X ₁ as shown in FIG. 1 (A), the beam spot at the second sweep position L ₂ is is swept, the sputtering beam is detected caused by the lead L ₂ in the second sweep position X _2, the beam spot is swept by a third sweep position X _3.

Since the third sweep position X ₃ does not intersect the lead L ₁ , sputter light is not generated and sputter light is not detected, it is determined that the bridge is not formed.

Further, as shown in FIG. 7B, the beam spots are sequentially swept at the respective sweep positions X in the same manner as described above, and all the sweep positions X
When the sputtered light is detected in, it is determined that a bridge is formed, and the bridge is detected.

〔Example〕

FIG. 3 is a front view showing the entire mounted printed circuit board automatic inspection apparatus to which the present invention is applied. 11 is a casing, and 12 is a printed circuit board P which is an object to be inspected and is placed in the casing. It is an XY stage that is moved and freely moved in the X-axis direction and the Y-axis direction. 13 is the XY stage above
12 is a light-receiving unit having a light-receiving surface shaped to cover the beam-irradiated portion of the printed circuit board, which will be described later, and sputter light is detected by a large number of light-receiving elements arranged on the light-receiving surface. It 14 is the above XY stage 12
Is a light receiver installed below the laser light source and receives the laser light passing through the light receiving unit 13 through a reference hole provided in the printed board when setting a reference point on the printed board. Reference numeral 15 is a group of operation switches provided on the upper surface of the casing 11, 16 is an indicator light indicating the operation state of the apparatus, and 17 is a printer for printing out the inspection result.

In this mounted printed circuit board automatic inspection device, inspection data such as the reference position on the inspected printed circuit board, the inspection position or the board name for identifying the type of the printed circuit board is registered in advance in the storage device or the like before the inspection. When performing the inspection, if the printed circuit board to be inspected is installed on the XY stage 12 and the board name and the like are input from a terminal device (not shown),
Pre-stored position information of the inspection point and whether the reflected light from the DUT (lead, solder, etc.) is reflected in the direction opposite to the beam irradiation direction or in the same direction as the irradiation direction (substantially Is automatically inspected based on the inspection data such as position information such as the location where the angle with the printed circuit board is smaller than 45 degrees or the location where the angle is larger than 45 degrees). The inspection results such as are printed out from the printer 17,
A mark (not shown) is provided near the bridge portion of the printed circuit board to be inspected.

FIG. 4 is a perspective view showing the optical system of the apparatus shown in FIG. 3, 21 is a He-Ne laser gun for emitting a laser beam, and 22 is the He-Ne laser for sufficiently narrowing the beam spot. gun
This is an expander for expanding the laser beam emitted by 21 into a parallel beam once to about 5 mm. Reference numeral 23 denotes a Y-axis rotating mirror 23a that scans the laser beam so that the beam spot is swept in the Y-axis direction of the XY stage 12, and similarly the laser beam is swept so that the beam spot is swept in the X-axis direction. This is a galvanometer having an X-axis rotating mirror 23b for scanning, and the galvanometer 23 scans the laser beam within a solid angle based on the movable range of each rotating mirror. A condenser lens 24 condenses the laser beam operated by the galvanometer 23 on the printed circuit board P via the first mirror 25 and the second mirror 26.

As shown in the figure, in this apparatus, a part of the laser beam scanned by the galvanometer 23 is separated by a beam splitter 27, and the beam B transmitted through the beam splitter 27 is printed on the printed circuit board as described above. The beam reflected by the beam splitter 27 is focused on the light receiving surface of the light spot position detecting element 29 by the second condensing lens 28 while being irradiated onto P, and is detected by this light spot position detecting element 29. The spot position of the beam B irradiated on the printed circuit board P is servo-controlled based on the position information of the beam spot.

FIG. 2 is a block diagram of the printed circuit board automatic inspection device described above. The processing device 1 is provided with a storage device (not shown), and X is determined based on the inspection data stored in advance in this storage device. -When the Y stage 12 is driven and the bridge inspection point on the printed circuit board P is moved within the irradiation range of the laser beam B, the galvanometer 23 is controlled to sweep three points between the mounting component holes as described later. The beam spot of the laser beam B is swept at the position, and the sputtered light of this beam spot is detected by the light receiving unit 13 to inspect the bridge.

FIG. 6 is a diagram showing an example of bridge detection according to the present invention, and shows a case where a bridge inspection is performed on a constant pitch printed circuit board in which component holes are arranged at a constant pitch.

When this printed circuit board is inspected, the laser beam is irradiated within a range that covers a certain number of component holes H, as indicated by the broken line in FIG. 6A, based on the inspection data. At the inspection point where the galvanometer 23 is driven and the bridge is detected, as shown in FIG.
Sweep position X ₁ on the vertical bisector of the line segment connecting H ₁ and H ₂ and sweep positions X ₂ and X ₃ on both sides of the line are preset three sweep positions as shown by arrows in the figure. At the first sweep position X ₁ ,
The inspection is performed by sweeping the beam spot in the order of the second sweep position X ₂ and the third sweep position X ₃ .

FIG. 5 is an operation flow chart at the time of the bridge inspection performed under the control of the processing device 1. The galvanometer 23 is driven by the control of the processing device 1 to sweep the beam spot at each sweep position as described above. While the process is being performed, the output signal of the light receiving unit 13 is monitored by the processing apparatus 1, and if there is even one sweep position where sputtered light is not detected, it is immediately determined that a bridge is not formed. Inspection is started at the next bridge detection position, and if sputter light is detected at all sweep positions, it is determined that a bridge is formed, and bridge detection is performed at the next bridge inspection location.

When the inspection in one inspection block in the driving range of the galvanometer 23 is completed in this way, the XY stage is driven and the same inspection is performed in the next inspection block.

Generally, there are few bridges or bent leads. Therefore, if the bridge inspection is performed at the next inspection point at the time when the sputtered light is detected as described above, most of the inspection points are judged to have no bridge in one sweep, and the next inspection point is inspected. There is almost no effect on the inspection time because it moves to.

As shown in FIG. 6 (C), assuming that the pitch of the component holes H of the printed circuit board is 2.54 mm and the distance between the lead wires D of the component holes is 1.54 mm, the above three sweep positions If the interval is set to 0.5 mm and the inspection is performed, the conductive spot is not irradiated with the beam spot, so that erroneous detection can be avoided.

Needless to say, such setting of the interval between the sweep positions can be stored in the inspection data.

Further, in the above-described embodiment, the case where the beam is swept in the direction intersecting the line segment connecting the component holes has been described, but the beam is swept in the direction intersecting the line segment connecting the patterns which are the component mounting portions. Of course, it is okay.

〔The invention's effect〕

As described above, the present invention irradiates a beam toward a DUT (lead, solder, etc.) in which reflected light is reflected upward from a vertical direction with respect to a printed circuit board, and
The beam is swept in a direction intersecting with a line segment connecting the component mounting parts (holes), and it is determined to be a bridge when all the reflected light of the swept number is detected by the light receiving part. As a result, the inspection performance of the bridge inspection can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of the mounted printed circuit board automatic inspection device of the present invention, FIG. 2 is a block explanatory diagram of the mounted printed circuit board automatic inspection device to which the present invention is applied, and FIG. 3 is applied to the present invention. FIG. 4 is a diagram showing the entire mounted printed circuit board automatic inspection device, and FIG. 4 is a diagram showing an optical system of the mounted printed circuit board automatic inspection device to which the present invention is applied. FIG. 5 is an operation flowchart at the time of bridge inspection of the embodiment, FIG. 6 is a diagram showing an example of bridge detection according to the present invention, and FIG. 7 is a diagram explaining erroneous bridge detection. P: printed circuit board to be inspected, H: component hole, B: beam, X: sweep position.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 61-76940 (JP, A) JP 60-133968 (JP, A) JP 57-196140 (JP, A) JP 63- 177044 (JP, A)

Claims (1)

[Claims] 1. A printed circuit board bridge inspection is carried out by irradiating a printed circuit board to be inspected with a narrowly focused beam, and detecting the reflected light reflected by the reflected light in a direction opposite to the beam irradiation direction. In the printed circuit board automatic inspection apparatus, an opening is formed through which the beam passes vertically toward the printed circuit board to be inspected, and the beam irradiation surface of the printed circuit board to be inspected is covered and a light receiving surface surrounding the irradiated beam is formed. And a means for sweeping the beam a plurality of times in a direction intersecting a line segment connecting a component mounting portion (hole) to which the electronic component is soldered, and the light receiving portion for the reflected light of the number of sweeps. An automatic inspection apparatus for mounted printed circuit boards, comprising: a processing device that determines that a bridge exists when all light is received.