JPH02211586A - Device and method for inspecting conductive pattern - Google Patents

Abstract

PURPOSE:To quickly and exactly execute an inspection of a conductive pattern by comparing inspection object data and non-defective data, and deciding the quality with regard to a residual image area obtained by calculating the data based on its difference. CONSTITUTION:An IC package 20 being an inspection object is fixed to a bed 22. As a result, binary data of a pattern which becomes the inspection object is inputted to a memory 42. Subsequently, a CPU 48 compares this inspection object data and non-defective data (that which is stored in advance in a RAM 50) and calculates data based on its difference. In such a way, a residual image 72 is obtained. In this case, when a high speed processing is required, a data compression is executed, a residual image area is derived by decreasing the data quantity, and in accordance with whether this residual image area is large or small, the quality is decided. On the other hand, when a precise decision is required, the residual image area, an inclination, length of a major axis, etc. are calculated and stored. From its result, an image error or not is decided. When it is decided not to be an image error, a kind of a residual image pattern is recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus and method for inspecting conductive patterns on inner leads of IC packages, printed circuit boards, etc.

[Prior Art] Conventionally, visual inspection has been used to inspect conductive patterns such as inner leads of IC packages and printed circuit boards. That is, the conductive pattern to be inspected is visually observed directly or through a microscope or the like to detect short circuits or breaks in the pattern.

[Problems to be Solved by the Invention] However, the conventional inspection method as described above has the following problems.

First, since the inspection is done visually, there is a problem in that the inspection quality varies depending on the operator.

Second, there was also the problem that testing took time.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an apparatus and method for quickly and accurately inspecting conductive patterns.

[Means to solve the problem] FIG. 1 shows an overall configuration diagram of an inspection apparatus according to the present invention.

This inspection device includes an imaging device 4, a binarization means 6, a non-defective product data storage means 8, a judgment means 10. An output device 12 is provided.

[Operation] The imaging device 4 captures the conductive pattern 2 to be inspected as an image. The binarization means 6 binarizes the output data from the imaging device 4 according to a predetermined threshold value and outputs inspection target data. On the other hand, in the non-defective product data storage means 8,
Binarized video data regarding non-defective patterns is stored. The determination means 10 compares the output of the binarization means 6 (i.e., inspection target data) and the output of the non-defective product data storage means 8 (i.e., non-defective data), and based on the difference,
Create residual image data. Further, the determining means 1O determines whether the conductive pattern is good or bad based on this residual image data.

Further, in the inspection apparatus according to the second aspect, residual image data is not created near the ends of the conductive pattern. This makes it possible to make a judgment while ignoring differences in parts that do not affect the quality of the pattern.

[Example] FIG. 2 shows the hardware configuration of the inspection device according to the present invention.

On the main bus 46 are a CPU 48 and a ROM-RAM 5.
0 is set. C RT 12, which is an output means;
The input key 32 for inputting commands etc. is the I/F
3840 to the main bus 46. The IC package 20 and the like having the pattern 2 to be inspected are fixed on the bed 22. This bed 22
are movable by motors 24, 26, 28.

The CPU 48 can place the bed 22 at a desired position via the I/F 44 and the motor controller 36.

At the top of the IC package 20, there is a CCD which is an imaging device.
A camera 4 is provided. The output of the CCD camera 4 is accumulated in a buffer 30, converted into a digital signal by an A/D converter 34, and then stored in a memory 42.

In this embodiment, when inspecting a pattern, a non-defective pattern is first created, and then the actual inspection is performed.

Therefore, first, the creation of a non-defective pattern will be explained.

FIG. 3 is a flowchart showing a program for creating a non-defective pattern. This program is ROM50
The CPU 48 controls each device accordingly.

First, IC package 2, which is known to be a good product,
0 is fixed on the bed 22. The CCD 4 captures this non-defective pattern and sends a signal to the A/D converter 34. In step S, the CPO 48 captures the digitally converted output into the memory 42. In this embodiment, the analog signal from the CCD 4 is binarized using a predetermined threshold. That is, the memory 42
"Oj" or "1" depending on the presence or absence of the pattern.
' is memorized. In this example, the number of pixels is 51
It was set to 2×484 pixels. FIG. 4A schematically represents data stored in the memory 42. Here, the shaded area is “
1'', that is, a certain part of the pattern.

As is clear from FIG. 4A, the edges of the captured pattern are wavy. Therefore, this was shaped into a good master pattern as shown in Figure 4B (step si).
. This good product master pattern is stored in the RAM 5G.

Next, dead zone data is created (step S4).

The meaning of the dead zone data is as follows. In actual inspection performed later, the pattern to be inspected does not completely match the non-defective master pattern, and there are usually slight differences. In particular, this minute difference occurs near the ends of the pattern. Therefore, by excluding the vicinity of the end of the pattern from the object of comparison inspection, such minute differences, which have no relation to the quality of the pattern, can be removed from the object of calculation. The pattern portion excluded from the inspection target in this way is called dead zone data.

In this embodiment, the width E of the dead zone data in FIG. 4C is approximately several percent of the pattern width W in FIG. 4B. The dead zone data of FIG. 4C is stored in the RAM 50 (step S,).

Preparation for inspection is completed as described above. Next, the actual inspection process will be explained. FIG. 5 is a diagram illustrating the actual inspection program as a flowchart.

An IC package 20 to be inspected is fixed to a bed 22. In step S1°, the binarized data of the pattern to be inspected is loaded into the memory 42; FIG. 6A shows this data.

Next, the CPU 48 compares this inspection target data with non-defective data (stored in the RAM 50 in the preparation stage) and calculates data based on the difference (step S1). Furthermore, from this data, those belonging to the dead zone are removed (steps S,'), and residual image data is calculated (steps S, 3).

The residual image 72 obtained in this way is shown in FIG. 6B.

Next, in step S14, it is determined whether or not to compress this residual image data. When high-speed processing is required, perform data compression (step S!4) to reduce the amount of data, and then calculate the remaining image area (step S*s).
. The quality of the image is determined based on the size of the remaining image area (step 526).

On the other hand, if precise determination is required, step 315
-3! . Then, the remaining image area, inclination, major axis length, fillet diameter, etc. are calculated and stored. Here, fisi means Fig. 8A
Refers to a rectangle 70 circumscribing a residual image 72, as shown in FIG.

Next, based on the above calculation result, it is determined whether or not there is an image error (step S2). In other words, if the pattern is thick (or thin) beyond the dead zone and the pattern is not defective, it is judged as an image error and a good product is determined.

If it is not an image error, the type of residual image pattern is recognized based on the above calculation result (step 5tt). C.P.
U48 performs this recognition based on the table on the next page.

FIGS. 7A to C1 and FIGS. 8A to D show residual image patterns corresponding to the table on the previous page.

Next, in step S11.5211, quality is determined based on the type of residual image pattern. In this embodiment, islands, pinholes, and pattern shorts are determined to be defective. The above judgment results and the pattern being processed are displayed on the CRT 12.

Note that the above embodiments have been described with reference to IC packages, or may be applied to those having conductive patterns such as printed circuit boards.

Further, in the above embodiment, processing is implemented by a microprocessor, but the entire process may be configured by a hard logic circuit.

[Effects of the Invention] In the inspection apparatus and method of claim 1.3, quality is determined based on residual image data based on the difference between non-defective product data and data to be inspected.

Therefore, the conductive pattern can be inspected quickly and accurately.

Further, in the inspection apparatus according to the second aspect of the present invention, residual image data is not created near the ends of the conductive pattern.

Therefore, differences unrelated to the quality of the pattern can be eliminated,
Even faster processing is possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall configuration of the present invention, FIG. 2 is a diagram showing the hardware configuration of an inspection device according to an embodiment of the present invention, FIG. 3 is a flowchart of a non-defective pattern creation program, and FIGS. Figure 5 is a flowchart of the pattern inspection program; Figure 6A is a diagram showing image data;
FIG. 6B is a diagram showing residual image data. FIGS. 7A to C1 and FIGS. 8A to D are diagrams showing patterns of residual images. 2... Conductive pattern 4... Imaging device 6... Binarization means 8... Non-defective data storage means lO... Judgment means 12... Output device.

Claims (3)

[Claims] (1) An imaging device that captures the conductive pattern to be inspected as an image; a binarization means that binarizes the output data from the imaging device using a predetermined threshold value and outputs the data to be inspected; A non-defective data storage means for storing digitized video data, residual image data is created based on the difference between the inspection target data output from the binarization means and the non-defective data stored in the non-defective data storage means, and the remaining image data is inspected. A conductive pattern inspection device comprising: a determining means for determining the suitability of a target conductive pattern; and an output device for outputting a determination result by the determining means. (2) The conductive pattern inspection apparatus according to claim 1, wherein the determining means does not create residual image data near the ends of the conductive pattern. (3) The conductive pattern to be inspected is captured as an image and converted into an analog electrical signal, and the analog electrical signal is binarized using a predetermined threshold value to become the data to be inspected. This data to be inspected is prepared in advance. The apparatus is characterized in that it compares the data with the data of a non-defective product, creates residual image data based on the difference, determines the suitability of the conductive pattern based on the obtained residual image data, and outputs the determination result by the determination means. Method for inspecting conductive patterns.