JPH01219656A - Inspecting method of mounted printed circuit board - Google Patents

Abstract

PURPOSE:To facilitate the automation of an inspecting apparatus, by measuring either height or luminance along the periphery of a land part of a printed circuit board whereon components are mounted, so as to inspect or determine the miss of a solder bridge or a lack of component. CONSTITUTION:On a substrate, electrodes 1, 2 of a chip component 5 are soldered to land parts 3, 4, and a circuit pattern 2 is already subjected to a resist treatment. Inspection tracks 7, 8 are prescribed beforehand along the vicinity of the periphery of the lands 3, 4. The positions and shapes of the tracks 7, 8 are memorized beforehand in an automatic inspecting machine, and the automatic inspecting machine measures sequentially the height or luminance of the tracks 7, 8 along them.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for inspecting a mounted printed circuit board, and in particular to an inspection method for automating the inspection and determination of non-conductor bridges using a computer or the like. be.

BACKGROUND OF THE INVENTION Conventionally, inspection of mounted printed circuit boards, especially inspection of solder bridges, has mostly relied on the human eye.

Problems that the invention aims to solveHowever, in recent years, the miniaturization of printed circuit boards, miniaturization of parts,
As packaging density increases and component insertion machines become faster, greater accuracy and speed are required than ever before, and visual inspection is no longer sufficient. In addition, in the inspection of NO-λ bridges, it is difficult to predict where NO-ND bridges will occur, so the inspection method is generally complicated, and there is a problem that there is no simple inspection method that can be tested with a microcomputer, etc. There is.

In view of these problems, the present invention aims to provide an inspection method that can be used to inspect missing parts at the same time as inspecting Nadapurinoji, and because it uses a simple algorithm, it can be realized using a microcomputer or an electric circuit. It is something to do.

Means for Solving the Problems The present invention sequentially measures at least one of height or brightness along the periphery of a land on a printed circuit board after components are mounted, and calculates changes in the measured value according to a predetermined change. This is an inspection method for the mounting source printed circuit board that determines whether there are any gaps or missing parts by comparing the differences between the two.

According to the method described above, it is possible to inspect and determine whether solder bridges or missing parts on the mounting source printed circuit board are present using a microcomputer or an electric circuit, and automation of the inspection equipment is easily possible. It is.

Embodiments Hereinafter, embodiments for achieving the objects of the present invention will be described with reference to the drawings.

Figure 1 is an enlarged view of a printed circuit board on which electronic components are normally mounted. 3 and 4 are land parts to which electrodes 1 and 2 of chip component 5 are soldered, and 6 is a resist-treated circuit pattern. be. Reference numerals 7 and 8 are inspection lines predefined along the vicinity of the outer periphery of the lands 3 and 4, and the positions and shapes of the inspection lines 7 and 8 are memorized in advance in the automatic inspection machine. The automatic inspection machine is configured to sequentially measure the height or brightness (reflectance) along this inspection line 7.8.

FIG. 2 shows the inspection results obtained by measuring the height using an automatic inspection machine along the inspection track 7 shown in FIG. .11
It represents the change in height when scanning along the path. That is, a portion A indicating the presence of the chip component 5 is detected between points 12 and 13, a portion B indicating the presence of the circuit pattern 6 is detected between points 14 and 11, and points 11 and 122 and points 13 and 14 are detected. It shows that there is nothing in between. The waveform shown in Figure 2 is stored in advance in the inspection machine as a waveform during normal component mounting.The stored waveform is compared with the waveform of the inspection result, and the presence or absence of a difference is determined to be normal. It is determined whether or not component mounting is being carried out.

FIG. 3 shows the chip component 5 mounted on the board together with the solder bridge 18. Note that 15.16 is another land portion disposed close to the land 3.4, and 17 is a second chip component mounted between the land portions 15.16.

FIG. 4 shows that in the inspection results when the device is mounted as shown in FIG. 14
It can be seen that there is a solder bridge between them. Just to be sure, in Figures 2 and 4, by measuring the distance from point 12 to the point where section A occurs, the chip component 5 is
It is also possible to detect a shift in the position of the

FIG. 5 shows changes in brightness when scanning is performed along the same inspection path 7 as in FIG. 3. This shows that if there is a solder bridge that cannot be detected based on height changes, it is possible to avoid missing it by taking measurements that also take luminance information into account. This is because when scanning the outside of the copper foil portion, the solder surface has a higher reflectance and higher brightness than the printed circuit board surface. Referring to FIG. 5, there is a gap between points 13 and 14 indicating that a solder bridge 18 exists. Note that the reason why the brightness between points 12 and 13 is high is because the reflectance of the electrode portion 1 of the chip component 6 is high.

FIG. 6 shows a case where the chip component 6 is mounted on the printed circuit board in a shifted manner.

FIG. 7 shows the inspection results when mounted as shown in FIG. 6. As shown in FIG.
It shows the change in height when scanning along the path of points 11, 12, 13° and 14.11. Although there is no solder bridge, the height between points 12 and 13 is the same as point 1 in Figure 2.
It is abnormally low compared to the height between 2 and 13, indicating that some parts are missing.

In addition, in the above embodiment, the land portion is rectangular and b
However, in the present invention, even a land portion having an arbitrary shape can be scanned as a circumscribed rectangle, regardless of the shape of the land portion.

Effects of the Invention As described above, according to the present invention, by measuring at least one of the height and brightness along the periphery of the land portion of the printed circuit board on which the component is mounted, fine lines that cannot be detected by the human eye can be measured. Since it is possible to inspect even solder bridges and is a simple method, it can provide an optimal inspection method for automatic machines.

[Brief explanation of the drawing]

Figure 1 is an enlarged view of the main parts of the printed circuit board with components mounted.
FIG. 2 is a characteristic curve diagram showing the test results of the printed circuit board according to the present invention, FIG. 3 is an enlarged view of the main parts of the printed circuit board when it is mounted with a solder bridge, and FIGS.
The figure is a characteristic curve diagram showing the inspection results of the printed circuit board in Figure 3, Figure 6 is an enlarged view of the main parts when components are mounted on the board with misalignment, and Figure 7 is the printed circuit board in Figure 6. This is a reproducibility curve showing the test results. 1.2...Electrode, 3,4...Land part, 5...Chip component, 6...Circuit pattern, End, 8...・Inspection track, 11.12,13
．． 14... Point of inspection line, 15.16...
...Land part, 17...Second chip component,
18... No Tsuta Bridge. Name of agent: Patent attorney Toshio Nakao and one other person 1.
2-t! 7.8-Inspection road No. 2 Hinoki inn road □ Fig. 4++ 12 13 14 I+Inspection**
Turn □ Figure 5 & Survey route □

Claims (2)

[Claims] (1) The height is sequentially measured along the periphery of the land of the printed circuit board that has gone through the mounting process of soldering a predetermined electronic component to a predetermined land, and the measured height change curve is A method for inspecting a mounted printed circuit board, characterized by comparing the change curve with a predetermined change curve and determining the presence or absence of a solder bridge or missing component based on the presence or absence of a difference. (2) The brightness is sequentially measured along the periphery of the land of the printed circuit board that has gone through the mounting process of soldering a predetermined electronic component to a predetermined land, and the measured brightness change curve is compared with the predetermined curve. 1. A method for inspecting a mounted printed circuit board, the method comprising comparing the change curve with a predetermined change curve, and determining the presence or absence of solder bridges and missing parts based on the presence or absence of a difference.