JPS61189443A - Printed circuit board pattern inspection equipment - 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 [Field of Application of the Invention] The present invention relates to a printed circuit board pattern inspection device, and particularly to a printed circuit board having a fine pattern that detects the pattern of the printed circuit board as a binary image and determines its acceptability. The present invention relates to a printed circuit board pattern inspection and preparation suitable for.

[Background of the invention]

As shown in the fifth factor, the conventional printed circuit board pattern inspection apparatus uses a halogen lamp 30 on the surface of the printed circuit board 11.
1, etc., through a condensing lens 302, and the reflected light from the surface of the copper foil section 111 is passed through a focusing lens 303, and is received and imaged by a COD camera 304, etc., to obtain a pattern image. I ran into a lot of stuff.

In this method, strong reflected light can be obtained when the surface of the copper foil section 111 is uniform and cleanly polished, but if the surface of the copper foil section 111 is dirty or scratched, Alternatively, if there is a blackened residual copper part due to etching obscurity, it becomes a weak reflection source or diffusely reflected light, and a normal part of the conductor pattern is determined to be a defect, resulting in a short-circuit defect between patterns being overlooked. Furthermore, printed circuit boards in recent years have become denser, and the copper foil pattern width of multilayer boards for large computers and some printed circuit boards for office automation equipment has become finer, ranging from tens to hundreds of microns. For such fine patterns, dust and fibers attached to the surface can be considered as defects in the pattern.
This has the disadvantage that the reliability of the inspection device is significantly reduced. There is also the problem that printed circuit boards that have been subjected to full-dare resist cannot be inspected.

Another conventional example is an inspection apparatus using a fluorescence detection method shown in FIG. In FIG. 6, a mercury lamp 401 is used as a light source, and a filter 4 that transmits ultraviolet rays of a specific wavelength is used.
02, is focused by a condensing lens 403, reflected by a No.-7 mirror 404, and irradiated onto the printed circuit board 11.

When ultraviolet rays act as excitation light, the printed circuit board 11
Fluorescence is induced from the base material portion 112 of. This fluorescence
The copper foil portion 111 is obtained as a silhouette image by transmitting the light through a -7 mirror 404, passing through a fluorescence transmission filter 405 and a focusing lens 406, and capturing the received light with a fluorescence detection camera 407. In this method, there is no influence from the surface condition of the copper foil portion 1110, but a false defect report is generated due to the adhesion of dust. Further, since the amount of fluorescence is generally weak, an expensive high-sensitivity imaging tube must be used as the fluorescence detection camera 407, and the screen must be temporarily stopped for two-dimensional imaging. Therefore, scanning the entire surface of the printed circuit board 11 requires step and repeat control of the table, and as a result, there is a drawback that the throughput of the inspection apparatus is significantly reduced. Furthermore, printed circuit boards coated with Tsurudaregis cannot be inspected.

[Purpose of the invention]

The present invention has been made in view of the above, and its purpose is to avoid being affected by the condition of the surface of the copper foil.
Another object of the present invention is to provide a printed circuit board pattern inspection device that can reduce false alarms due to dust and can perform continuous scanning.

[Summary of the invention]

The present invention is characterized by a table that moves in the X and Y axis directions for fixing a printed circuit board having a two-dimensional pattern represented by x and Y coordinates, and a hot air blowing hot air locally onto the surface of the printed circuit board on the table. an infrared light detection device that sequentially scans the surface of the printed circuit board that is locally heated with hot air, which is provided at a position facing the printed circuit board, and a signal obtained by the infrared light detection device; A binarization circuit that accurately separates the copper foil part signal and the base material part signal of the printed circuit board by a binarization method, and a binarization pattern signal from this signal binary 1-hi circuit is used to convert the above printed circuit board into a binary pattern signal. and a defect determination circuit for determining the quality of the copper foil pattern.

[Embodiments of the invention]

The present invention will be explained in detail below using the first factor, the embodiments shown in FIGS. 2 and 4, and FIG.

FIG. 1 is a conceptual diagram showing an embodiment of the printed circuit board pattern inspection apparatus of the present invention. In FIG. 1, a printed circuit board 11, 12 to be inspected having a two-dimensional pattern is fixed to a fine adjustment ΔX table 31 and a ΔY table 32 provided on an X table 21 movable in the X-axis direction. The X table 21 is a Y table 2 that is movable in the Y axis direction.
2, 23 is an X table drive motor, 24 is a Y table drive motor, 33 is a ΔX table drive motor, and 34 is a ΔY table drive motor.

41 is a base, and 42 is a linear ball bearing.

At this time, the printed circuit boards 11 and 12 are positioned by a guide bin method or a mechanical method based on the board edge reference.
．． Positioning can be performed with an accuracy of about 1 to 0.2 m.

Reference numerals 54 and 52 denote image detection units that fix the same positions on the printed circuit boards 11 and 12 at positions where images are to be taken, respectively. The output signals of the image detection units 51 and 52 are respectively sent to the binarization circuit 6.
1.62, it is temporarily stored as a binary pattern signal in the data storage devices 71.72 arranged in a matrix, and sent to the defect determination circuit 80 to detect disconnections, shorts, irregularities, pinholes, etc. in the pattern. Defects such as residual copper adhesion are extracted.

90 is a positional deviation detection circuit, and 99 is a control circuit.

FIG. 2 is a plan view showing an example of the board layout of the printed circuit board to be inspected in FIG. 1. In Figure 2, 1
01 is the alignment guide pin hole, 102 is the outer periphery of the board,
Reference numeral 103 indicates the outside and line of the finished printed circuit board, and 104 indicates the printed pattern area.The inspection range is the printed pattern area 104, and the inside of the finished outer line of the printed circuit board 103 is also inspected if necessary.

Corner patterns P1 located at the four corners of the substrate outer peripheral portion 102
~P4 is a boundary line that forms a right angle between the base material part 112 of the printed circuit board 11 (12) and the copper foil part 111 (see prisoner 4), and that right-angled boundary line is parallel to the table movement axis X.
Since it coincides with the Y direction, one or more locations are used for accurate alignment and for detecting dimensional differences, misalignment, etc. between the substrates.

FIG. 3 is a diagram showing an example of a defect mode of a printed circuit board pattern, where 111 is a copper foil part, 112 is a board part, 113 is a disconnection, 114 is a chip, 115 is a pinhole, 116 is a short part, and 117 is a protrusion. , 118 is residual copper, and when etching non-light components occur in the etching process, the thickness of the copper foil remains halfway and the surface thereof remains in a blackened state.

The present invention detects the defect pattern shown in FIG. 3 using the apparatus having the fC configuration shown in FIG.

By the way, when the pattern shown in FIG. 3 is viewed on a TV screen using the conventional reflected light detection method shown in FIG. 5 as an image detection method, the copper foil portion 111 appears white and the base material portion 112 appears black. If there is dust attached to the foil part 111, the reflected light from that part will not be obtained and it will appear black on the screen.
As a result, disconnections, pinholes, or defects in the pattern are determined to be defects. Further, even if the short pattern is blackened residual copper, normal reflected light cannot be obtained and it appears black on the secondary image surface, and as a result, it is determined that there is no copper foil pattern in that part. In this case, a short circuit defect may be overlooked, and the reliability of the inspection device will be significantly reduced.

In addition, in the case of the conventional fluorescence detection method, the black and white images described above are obtained inversely, and the blackened residual copper part can be recognized as a copper foil pattern, and the missed defect like the former does not occur.
Since the dust adhering to the base material part 112 blocks the ultraviolet light for excitation υ and also blocks the fluorescence from the base material part 112, it is determined that residual copper has adhered, resulting in a false alarm defect.

Therefore, in the present invention, the image detection section 51. of FIG.
52, an infrared light detection method shown in the embodiment shown in FIG. 4 is adopted. In FIG. 4, 201 is an infrared photodetector, 202 is a hot air injection nozzle, and the injection nozzle 20
2, the air heated by the heater wire 203 is jetted as hot air by the blower 204, and is blown onto the local surface of the printed circuit board 11 (12). In this case, since the copper foil portion 111 with high thermal conductivity is extremely small in both thickness and width, it is heated instantaneously and evenly;
Since the base material portion 112 absorbs heat slowly, a large temperature difference occurs between the two. Therefore, this temperature difference is detected by the infrared light detector 201 from the emitted infrared rays through the focusing lens 205, and the binarization circuits 61 and 62 shown in FIG.
By passing through the copper foil section 111, a clear pattern of the copper foil portion 111 can be obtained.

Note that the moving speed of the printed circuit board 11 (12), the hot air temperature, the distance between the imaging axis and the hot air blowing point, etc. are adjusted in advance to optimal values in correspondence with the signal binarization level.

According to the embodiment described above, it is not affected by the copper foil surface condition;
It is also possible to inspect a printed circuit board provided with a Tsuruda resist 1-a, and a satisfactory inspection throughput can be obtained by continuous scanning.

In addition, most of the dust on the shiblint board 11 (12) is removed by the hot air jet, and even if it remains, the copper foil part 1
There is no such influence that the signal level of No. 11 is lowered to the point where it cannot be converted to the t-binarization level, stable images can always be obtained, and a highly reliable printed circuit board pattern inspection apparatus can be obtained. Furthermore, a plurality of hot air jet nozzles 202 may be provided, and by combining them front, rear, left and right with respect to the direction of substrate movement, it is possible to deal with the reciprocating movement of the substrate and to improve the dust removal rate.

〔Effect of the invention〕

As explained above and as follows, according to the present invention, it is possible to reduce false alarms due to dust without being affected by the condition of the surface of the copper foil, and to enable continuous scanning. It is also possible to respond to various conditions, and has the effect of significantly improving test reliability.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an embodiment of the printed circuit board pattern inspection apparatus of the present invention, FIG. 2 is a plan view showing an embodiment of the board surface layout of the printed circuit board to be inspected in FIG. 1, and FIG. Diagram 4 showing an example of a defect mode of a printed circuit board pattern
The figure is a configuration diagram of an infrared light detection type image detection unit showing an example of the image detection unit in Figure 1, and Figures 5 and 6 are configurations of conventional reflected light detection type and fluorescence detection type image detection units, respectively. Illustrated. 11.12... Inspection target printed circuit board, 21.22.
...
Signal binarization circuit, 71.72...Storage device, 80...
・Defect determination circuit, 90... Misalignment detection circuit, 99・
... Control circuit, 111 ... Copper foil part, 112 ... Base material part, 201 ... Infrared light detector, 202 ... Hot air injection nozzle, tit force 11 people] #1 Mouth #2 Eye 3 Tomoe//δ # 4 Eye/I (/2) Sheep 5

Claims (1)

[Claims] 1. A table that moves in the X and Y axis directions for fixing a printed circuit board having a two-dimensional pattern represented by XY coordinates, and blows hot air locally onto the surface of the printed circuit board on the table. A hot air jetting means, an infrared light detection device provided at a position facing the printed circuit board and sequentially scanning the surface of the printed circuit board that is locally heated with hot air, and an infrared light detection device that a signal binarization circuit that accurately separates the signal into a copper foil part signal and a base material part signal of the printed circuit board by a binarization method; and a binarization pattern signal from the signal binarization circuit. A printed circuit board pattern inspection apparatus comprising: a defect determination circuit for determining the quality of the copper foil pattern of the printed circuit board. 2. The printed circuit board has the same pattern.
The infrared light detection device is provided in two sets so as to face each of the printed circuit boards, and is configured to scan the surface of each of the printed circuit boards in synchronization, and the infrared light detection device is configured to scan the surface of each of the printed circuit boards in synchronization. 2. A printed circuit board pattern inspection apparatus according to claim 1, wherein the circuit is configured to determine whether local features of both patterns match or do not match.