JPH0213862A - Apparatus for inspecting printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a printed circuit board inspection device that generates an electron beam to scan one side of the printed circuit board for the purpose of simultaneously performing the external appearance inspection and wiring inspection of the printed circuit board. A fabric that performs wiring inspection by passing a current between an electron beam scanning device and each probe of a group of probes pressed against a printed circuit board, or by using the current generated in the pattern of a printed circuit board by the electron beam. The configuration includes a line inspection means and an appearance inspection means for performing an appearance inspection using secondary electrons emitted from the printed circuit board scanned by the electron beam, and the appearance inspection means is configured to perform an appearance inspection using secondary electrons emitted from the printed circuit board scanned by the electron beam. It consists of a collector that captures secondary electrons, a measuring device that measures the output of the collector, and an appearance discrimination circuit that compares the output of the measuring device with non-defective data. The configuration includes a measuring device that measures the current flowing between the cathodes of the electronic beer scanning device.

[Industrial application field]

The present invention relates to a printed circuit board inspection device, and more particularly to a printed circuit board inspection device that can simultaneously perform an external appearance inspection and wiring inspection of a through-hole type printed circuit board, a surface-mounted printed circuit board, etc.

[Conventional technology]

Conventionally, as shown in FIG. 4, a conventional printed circuit board appearance inspection apparatus captures a reflected image of coherent light such as a laser beam or sodium beam irradiated onto a printed circuit board 32 placed on an XY stage 31. An image pickup tube 33 such as a COD, and an image signal obtained by the image pickup tube 33 are transferred to an A/
An A/D conversion circuit 34 that performs D conversion, a master memory 35 that stores a good digital image signal, a central processing unit (CPU) 36 that reads out a good digital image signal from the master memory 35, and an A/D conversion circuit. 34 output and C
A determination circuit 37 that determines whether the printed circuit board 32 is a good product by comparing the output of the PU 36, and an A/D conversion circuit 34.
and a timing signal generation circuit 38 that generates a timing signal that controls the operation timing of the discrimination circuit 37.

Further, as shown in FIG. 5, a conventional printed circuit board wiring inspection device includes a press mechanism 44 that presses a probe group 43 supported by a head 42 onto a printed circuit board 41 from both upper and lower sides, and a probe group 43. A test power supply 4 applies a voltage to each probe via a switching circuit 45.
6 and the switching circuit 45 as the switching control circuit 4
A central processing unit (CPU) 48 controlled via a central processing unit (CPU) 7 and a switching circuit 45 detect wiring inspection data consisting of a current or voltage flowing through a pattern on a printed circuit board 41, and store this wiring inspection data in a mask memory 49. From C
A determination circuit 5 that determines whether the printed circuit board 2 is good or bad by comparing it with the wiring inspection data of a non-defective product read out via the PU4B.
0 and an operation panel 51 for operating the CPU 48 and press mechanism 44.

[Problem to be solved by the invention]

In the conventional wiring inspection apparatus described above, when attaching the upper and lower heads 42 to the press mechanism 44, especially in wiring inspection of surface-mounted printed circuit boards, the positions of the upper probe and the lower probe are made to correspond accurately. Because it is necessary,
It takes a long time to align the head 42 (in addition, since both sides of the printed circuit board 41 are covered with the head 42, it is impossible to perform an appearance inspection at the same time as a wiring inspection).

Therefore, in the past, visual inspection and wiring inspection were performed separately using separate inspection equipment, but in order to save on the installation space of the inspection equipment and the number of inspection man-hours, it is now possible to perform these inspections using the same inspection equipment. It has been desired to be able to process them simultaneously.

The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a printed circuit board inspection device that can perform visual inspection and wiring inspection at the same time.

[Means to solve the problem]

In order to achieve the above object, the printed circuit board inspection apparatus according to the present invention uses an electron beam b
The printed circuit board 1 is scanned by an electron beam scanning device 2 that generates an electron beam b1 and scans one surface of the printed circuit board 1, and by passing a current between each probe of the probe group pressed against the printed circuit board 1, or by using the electron beam b1 described above. wiring inspection means 20 that performs wiring inspection using the current generated in the pattern; and external appearance inspection using secondary electrons b2 emitted from the printed circuit board 1 scanned by the electron beam b1. The present invention is characterized in that it includes an inspection means 30.

As shown in FIG. 2, the appearance inspection means 30 includes a collector 7 that captures secondary electrons b2 emitted from a printed circuit board 9, a measuring device 9 that measures the output of the collector 7, and an output of the measuring device 9. Appearance discrimination circuit 13 that compares the data with the non-defective product data
It consists of

The wiring inspection means 20 also includes a probe group 3 and a measuring device 8 for measuring the current flowing between the cathode of the electron beam scanning device 2.

[Effect]

In the printed circuit board inspection device of the present invention, the probe group 3 is pressed against the other surface of the printed circuit board 1 and a current is passed through each probe to perform wiring inspection similar to the conventional method. One surface of the printed wood board 1 can be scanned by the electron beam b1 of the electron beam scanning device 2. At this time, when a part of the pattern passing from one side of the substrate 1 to the other side is irradiated with the electron beam b1, a current flows through the pattern, and this current is transferred to the wiring inspection means 20.
Wiring inspection data is obtained by measuring with the measuring device 8 that constitutes the. Then, by comparing the obtained wiring inspection data with the wiring inspection data of non-defective products as in the past, it is possible to determine whether the wiring condition of the printed circuit board under inspection is good or bad.

Furthermore, when the printed circuit board 1 is scanned by the electron beam b1, the secondary electrons b2 emitted from the printed circuit board 1 are captured by the collector 7 constituting the visual inspection means 30, thereby corresponding to the pattern of the printed circuit board 1. Visual inspection data is obtained, and by comparing the obtained visual inspection data with the visual inspection data of non-defective products, it is possible to determine whether the external appearance of the printed circuit board under inspection is good or bad.

In order to inspect the appearance of both sides of the printed circuit board 1, after carrying out the wiring inspection and appearance inspection as described above,
It is necessary to turn over the printed circuit board 1 and inspect the appearance of the other side of the printed circuit board 1.

In addition, if the pattern ends on one side of the printed circuit board 1, there is a problem that the appearance cannot be inspected because there is no change in the amount of secondary electrons emitted even if the electron beam b1 is irradiated. By providing a dummy pattern or a dummy through hole (via hole) that connects from a pattern on one side to the other side at the design stage of the board 1, the appearance can be inspected in the same way as the pattern that connects from one side of the printed circuit board 1 to the other side.

〔Example〕

The printed circuit board inspection apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS. 2 and 3 as follows.

As will be described in detail below, the printed circuit board inspection apparatus according to the present invention includes an electron beam scanning device 2, a probe group 3, a switch group 4, a measuring instrument 8, a wiring discrimination circuit 14, a switching control circuit 1'1, and a power source. A wiring test means 20 consisting of a device 5, a master memory 10 and a CPU 12, and a collector 7
, a measuring device 9 , a mask memory 10 which is also a part of the wiring testing means 20 , and an appearance inspection means 30 comprising a CPU 12 . Further, since the electron beam scanning device 2 operates in a vacuum, the electron beam scanning device 2
is built in a chamber mechanism 40 that can create a vacuum inside.

The electron beam scanning device 2 includes a power source 2a, a cathode 2b that generates an electron beam b1, an anode 2C that accelerates the electron beam b1, and a magnetic field deflection coil 2d that scans the electron beam b1 onto a printed circuit board 1. We are prepared.

As shown in FIG. 3, the chamber mechanism 40 includes a base frame 15 and a slide 17 disposed above the base frame 15 and driven up and down by a lift drive device such as a cylinder (not shown). The slide 17 is formed into a box shape with an open bottom, and its lower edge is brought into airtight contact with the peripheral edge of the base frame 15, and the inside is opened by operating the vacuum pump 18. Can be made into a vacuum state.

A net 19 is provided at the bottom of the slide 17 to hold down the printed circuit board 1 placed on the jig 16. It is made of fibers with Further, on the upper wall 17a of the slide 17, a cathode 2b, an anode 2C, and a magnetic field deflection coil 2d of the electron beam scanning device 2 are mounted.
is supported.

The upper surface of the base frame 15 is provided with a probe group 3 in which probes constituting the wiring inspection means 20 are arranged in a grid pattern, and a jig 16 for supporting the printed circuit board l above the probe group 3.

Here, the spacing between the probes of the probe group 3 is not particularly limited, and for example, 2,540 pitch, which is adopted as the standard distance between electrodes in the printed circuit board 1, may be used as the spacing. , different from this, each probe may be arranged corresponding to the electrode arrangement of the individual printed circuit board 1.

In addition, in order to make the probe group 3 arranged at a pitch of 2.54 m correspond to the printed circuit board 1 on which electrodes are arranged at a pitch different from this, one side has electrodes arranged at a pitch of 2.54 m, and the other An individualized head (not shown) having a probe group 3 arranged on a surface corresponding to the electrode arrangement of the printed circuit board 1 is prepared, and this individualized head is interposed between the probe group 3 of the base frame 15 and the printed circuit board 1. You may let them.

In this printed circuit board inspection apparatus, in order to increase the versatility of the inspection apparatus, the probes are arranged at a pitch of 2.54 mm, and individual heads are used as necessary.

Furthermore, the net 19 on the inner surface of both side walls 17b of the slide 17
A pair of left and right collectors 7 constituting the visual inspection means 30 are supported in an upper portion.

In addition to the above-described configuration inside the chamber mechanism 40, an electronic circuit for wiring inspection and appearance inspection is provided outside the chamber mechanism 40. Hereinafter, the electronic circuit section will be explained along with procedures for visual inspection and wiring inspection of the through-hole type printed circuit board.

First, place the printed circuit board 1 on the probe group 3 of the base frame 15.
Place. If the electrode spacing of the printed circuit board 1 differs from the standard, a suitable individualized head is used.

Thereafter, the slide 17 of the chamber mechanism 40 is lowered to press and fix the printed circuit board 1 to the probe group 3 with the net 19, and the lower periphery of the slide 17 is brought into airtight contact with the periphery of the base frame 15. Let them come into contact with you.

After that, the vacuum pump 18 is activated to bleed air from the chamber, and then the switching control circuit 11 controls the switch group 4 to sequentially connect each probe to the power source. 5 applies a predetermined voltage, the current flowing through the pattern of the printed circuit board 1 is measured by the measuring device 8, and the result is input to the wiring discrimination circuit 14. This measurement result is sent to the mask memory 10 in the wiring discrimination circuit 14.
The presence or absence of wiring defects such as disconnections and short circuits is determined by comparing the data with the wiring inspection data of non-defective products read out by the CPU 12 from the CPU 12 .

On the other hand, while voltage is being applied to each probe, the electron beam scanning device 2 is operated to scan the top surface of the printed circuit board 1 with the electron beam b1, thereby inspecting the wiring pattern extending from the top surface to the bottom surface.

In this wiring inspection using an electron beam, the electron beam b1 scans a pattern in which a voltage is applied to one end of the other side of the printed circuit board 1 by switching, and a predetermined amount of current is applied from the pattern to the cathode 2b. The amount of current is measured by the measuring device 8, and then the wiring judgment circuit 14 makes a judgment according to the above-described procedure.

If no defect is detected in the wiring inspection, the switching control circuit 11 applies a predetermined voltage to all probes, and the electron beam scanning device 2 is activated to scan the top surface of the printed circuit board 1 with an electron beam b1. The appearance of one side of the printed circuit board 1 is inspected by scanning the printed circuit board 1 with the .

In the visual inspection, when the electron beam b1 passes through a pattern to which a positive voltage is applied to one end from the other side of the printed circuit board l, a current flows through the pattern and secondary electrons b2 emitted from the pattern are captured by the collector 7. be done.

The change in the amount captured by the collector 7 is measured by the measuring device 9, and the result is stored in the mask memory 10 in the appearance discrimination circuit 13.
The presence or absence of appearance defects such as surface scratches is determined by comparing with the appearance inspection data of non-defective products read out by PUI2.

If no defect is detected as a result of the wiring inspection and visual inspection of one side, first raise the slide 17 and turn the printed circuit board 1 over to perform the visual inspection of the other side. Before placing the printed circuit board 1 on the jig 16, a conductive layer is placed between the probe group 3 and the printed circuit board 1 so that the appearance can be inspected without any problem even if the pattern of the reversed printed circuit board 1 is placed in a different position from its original position. A thin plate, for example a copper plate, is inserted. Thereafter, a predetermined voltage is applied to all the probes by the switching control circuit 11, and then the printed circuit board 1 is turned over and placed on the upper side of the thin plate, and the slide 17 is lowered to fix the printed circuit board 1. After that, the vacuum pump 18 is activated to bleed air from the space defined by the printed circuit board 1 and the slide 17, and then
By activating the electron beam scanning device 2 and scanning the upper surface of the printed circuit board 1 with the electron beam b1, the appearance of the other surface of the printed circuit board 1 is inspected.

Next, a procedure for visual inspection and wiring inspection of a surface-mounted printed circuit board using the above-mentioned printed circuit board inspection apparatus will be explained.

In this case, in the case of a single-sided printed circuit board, one head for individual handling is used for the front side, and in the case of a double-sided printed circuit board, two heads are used, one for the front side and one for the back side, as necessary. Individualized heads are used.

First, if necessary, the individual head for the front surface is set above the probe group 3, and the printed circuit board 1 is set thereon with the front surface facing upward.

Thereafter, the slide 17 is lowered, the net 19 presses the printed circuit board 1 against the individual head, and the lower periphery of the slide 17 is brought into close contact with the periphery of the base frame 15, and then the vacuum pump 18 is activated to open the chamber. Bleed the air inside. Then, in the same manner as in the case of a through-hole type printed circuit board, a wiring inspection of a pattern extending from one side of the printed circuit board 1 to the other side and an appearance inspection of the front side of the printed circuit board 1 are performed.

Furthermore, after this, the slide 17 is raised in order to perform a visual inspection of the back surface.

After this, in the case of a single-sided mounting printed circuit board, as in the case of a through-hole type printed circuit board, a conductive thin plate is placed on the probe group 3, and after applying voltage to all probes, the printed circuit board 1 is Turn it upside down and place it on a thin plate.
After lowering the slide 17, air is removed and the appearance of the back side is inspected.

In the case of a double-sided printed circuit board, an individual head for the back side is placed on the probe group 3 instead of an individual head for the front side, and wiring inspection and appearance inspection are performed in the same manner as for the front side.

Incidentally, in order to perform an appearance inspection on a pattern that is completely formed on one side, it is sufficient to form a dummy pattern or a via hole that communicates with the other side at the design stage of the printed circuit board 1.

In the printed circuit board inspection apparatus according to the embodiment described above, a display device for displaying the measurement results of the measuring device 9 or the discrimination results of the appearance discrimination circuit 13 may be provided.

〔Effect of the invention〕

As described above, according to the printed circuit board inspection apparatus according to the present invention, while applying a predetermined voltage to each probe in sequence,
While applying voltage to each probe, one side of the printed circuit board is scanned with an electron beam, and the points where one side of the printed circuit board connects to the other are detected based on the pattern and the current value flowing through the cathode. In addition to being able to conduct wiring inspections using a collector, secondary electrons generated when an electron beam scans one side or the other of a printed circuit board are captured by a collector, and the amount of secondary electrons is measured to perform visual inspections. I can do it.

Furthermore, when inspecting a surface-mounted printed circuit board, there is no need to match the upper and lower probes, and the inspection time including preparation time can be shortened.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the present invention, Fig. 2 is a block diagram showing an embodiment of the invention, Fig. 3 is a perspective view of a chamber mechanism used in the present invention, and Fig. 4 is a conventional external appearance inspection of a printed circuit board. FIG. 5 is a block circuit diagram of a conventional printed circuit board wiring inspection device. In the figure, 1... Printed circuit board, 2... Electron beam scanning device, 3... Probe group, 7... Collector, 8... Measuring instrument 9... Measuring instrument 13... Appearance discrimination Circuit 20...Wiring inspection means 30...Appearance inspection means BL...Electron beam, 81 of the morning's ML diagram, Figure 1! ! Minute 110 Kyo (P's Ox, 1 Diagram Reverse Luck Millicto @f Oath, 1 Scarcity 1 Fu Lock Circuit Diagram Diagram 4

Claims (1)

[Claims] [1] Generate an electron beam (b1) to generate a printed circuit board (1)
) by passing a current between the electron beam scanning device (2) that scans one surface of the printed circuit board (1) and each probe of the probe group 3 pressed against the printed circuit board (1), or by using the electron beam (b1) to scan the printed circuit board ( 1) Wiring inspection means (
20), and an appearance inspection means (30) that performs an appearance inspection using secondary electrons (b2) emitted from the printed circuit board (1) scanned by the electron beam (b1). Inspection equipment for printed circuit boards. [2] Collector (7) where the appearance inspection means (30) captures secondary electrons (b2) emitted from the printed circuit board (9)
The print according to claim 1, comprising: a measuring device (9) for measuring the output of the collector (7); and an appearance determining circuit (13) for comparing the output of the measuring device (9) with non-defective product data. Board inspection equipment. [3] The printed circuit board according to claim 1, wherein the wiring inspection means (20) comprises a measuring device (8) for measuring the current flowing between the probe group 3 and the cathode of the electron beam scanning device (2). Inspection equipment.