TWI467166B - Method and apparatus for inspecting pcb defects - Google Patents

Description

Fault detection method and fault detecting device

The invention relates to a fault detecting method and a device thereof, in particular to a fault detecting method for a circuit board and a fault detecting device thereof, which compare and judge a faulty component by a thermal image method.

The traditional printed circuit board (PCB) detection mostly uses the contact circuit board function detection. The method is to measure the voltage/current value of each test point one by one in the actual needle bed structure or simulation state. Although this method is more accurate, the cost of the test equipment, test fixtures and test development used is higher. In addition, the production of test fixtures and the development of corresponding test software are also quite time consuming.

On the other hand, with the development of electronic technology, the structure of the circuit board is more complicated. When the circuit fails, a large number of tests are needed to determine the fault point that caused the fault, and the previous fault point judgment relies on The work experience of the repair personnel themselves has neither consistent standard efficiency nor mass production characteristics.

In addition, during the fault detection process, the actual standard value and design value of the electrical values of the various components may be deviated, and each defective board needs to be measured first. The electrical values are compared as a standard, resulting in inefficient work and a waste of time.

Therefore, how to find a detection method can help to quickly locate the fault point of the circuit board, thereby avoiding the above-mentioned various kinds of defects, which is an extremely problem to be solved at present.

In view of the above problems, the present invention provides a fault detection method for a circuit board and a fault detecting device thereof, thereby solving the problem of non-uniform standard efficiency of the prior art and the problem of non-volume production characteristics, and solving the problem of time waste and being unable to be fast. Locate problems such as board fault points.

In order to achieve the above object, the present invention discloses a method for detecting a fault of a circuit board, comprising the steps of: taking a normal circuit board by a thermal image capturing unit to capture a standard thermal image and placing a circuit board to be tested. Positioning the fixture so that the positions of the plurality of components of the circuit board to be inspected correspond to the positions of the plurality of components of the standard circuit board, and the positioning fixture has a foolproof structure, so that the standard circuit board and the circuit board to be inspected They can only be installed in the positioning fixture in the same direction to ensure that the component positions of the standard circuit board and the circuit board to be inspected correspond to each other, and then the thermal image capturing unit captures a circuit board to be inspected to take a wait. Comparing the thermal image, then comparing it with a thermal image comparison unit The detected thermal image and the standard thermal image, by the heat distribution characteristics of the component, directly compare the abnormal component to speed up the detection efficiency.

The invention further discloses a fault detecting device, comprising: a thermal image capturing unit, configured to capture and capture a thermal image and a positioning fixture of each circuit board to be tested for operating radiant heat energy, and the positioning fixture further has A foolproof structure enables the standard circuit board and the circuit board to be tested to be installed in the positioning fixture only in the same direction to ensure that the component positions of the standard circuit board and the circuit board to be inspected correspond to each other for each The circuit board to be tested is such that the thermal image comparison is established at the same detection point and a thermal image comparison unit, comparing the thermal image of a functioning circuit board with the thermal image of a circuit board to be tested, The heat distribution characteristics of the components directly compare the abnormal components and speed up the detection efficiency.

The effect of the invention is that the thermal image circuit board fault detection method of the invention can not only perform non-contact circuit board function detection, but also find some poor circuit design, weakness of the part itself, or poor soldering, etc. Hidden problems.

Since any substance generates heat radiation, the present invention utilizes a thermal image capturing unit and a thermal image comparing unit to detect the amount of heat radiation emitted by the components of the circuit board due to operation, and when the components of the circuit board are thermally radiated. If the amount is significantly different from the normal value, the abnormal component can be quickly detected.

The invention utilizes a thermal image unit to detect components of a circuit board, which is convenient and time-saving and can avoid damage caused by contact detection. The detected radiant energy is then converted to a corresponding temperature and output as a voltage or current. By measuring and comparing the radiant energy on the surface of the board, the cause of the fault can be found in a short time.

The features, implementations, and utilities of the present invention are described in detail below with reference to the drawings.

Please refer to Figure 1 and refer to Figure 2 together. FIG. 1 is a flow chart of a fault detecting method according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a fault detecting apparatus according to an embodiment of the present invention.

2 is a fault detecting apparatus 100 according to an embodiment of the present invention, which is applicable to a circuit board 120 to be inspected. The circuit board 120 to be inspected is electrically provided with a plurality of components, such as a metal oxide semiconductor (MOS) and a capacitor ( Electronic components such as a central processing unit (CPU), a graphics processing unit (GPU), and the like. The fault detecting apparatus 100 of the embodiment of the present invention includes: a positioning fixture 140 for a standard circuit board and a circuit board to be inspected, a thermal image capturing unit 160, and a thermal image comparing unit 180. , electrical connection thermal image capture The unit 160, the thermal image comparison unit 180 receives and compares the standard thermal image with the to-be-compared thermal image.

The fault detection method according to an embodiment of the present invention, after the detection system is set, includes the following steps: positioning the fixture 140 such that each of the to-be-detected circuit boards 120 has the same detection point (step 200), with a heat The image capturing unit 160 captures a standard circuit board placed on the positioning fixture 140 to capture a standard thermal image (step 300).

Next, placing a circuit board 120 to be inspected on the positioning fixture 140 causes the positions of the plurality of components of the circuit board 120 to be inspected to correspond to the positions of the plurality of components of the standard circuit board (step 400), to the thermal image capturing unit 160. The circuit board 120 to be inspected is photographed, and a thermal image to be compared is captured (step 500).

Then, a thermal image comparison unit 180 compares the thermal image to be detected with the standard thermal image (step 600), and the thermal distribution characteristic of the component directly compares the abnormal component and determines that the component is a faulty component. In order to speed up the detection efficiency.

Please refer to Figure 1 and refer to Figure 3. FIG. 3 is a block diagram of a fault detecting apparatus according to another embodiment of the present invention.

A circuit board failure detecting apparatus 100 according to another embodiment of the present invention, wherein a thermal image and a standard heat of a circuit board to be inspected (such as 120 shown in FIG. 2) The result of the comparison of the images is stored by a memory unit 182 and displayed through a display unit 184.

In addition, the thermal image capturing unit 160 of the embodiment further includes: a lens unit 162 and a thermal image temporary storage unit 164, wherein the lens unit 162 is configured to capture a standard thermal image and a to-be-matched thermal image, and the thermal image temporary storage unit The 164 is used to temporarily store the analog data of the standard thermal image taken by the lens unit 162 and the thermal image to be compared.

In the fault detection method of the embodiment, one of the lens units 162 is used by the thermal image capturing unit 160 to capture a thermal image to be compared with one of the circuit boards 120 to be detected. The thermal image capturing unit 160 temporarily stores the analog data of the thermal image captured by the thermal image capturing unit 160 by using one of the thermal image temporary storage units 164.

In the fault detection method of the embodiment, the circuit board 120 to be detected is implemented by the positioning fixture 140 through an application to have the same detection point. The application performs boundary scan of the circuit board 120 to be tested and the standard circuit board as the basis of the comparison of the two thermal images, so that the comparison of the thermal images of the circuit board 120 to be tested and the standard circuit board is established at the same detection point. on.

Wherein, those skilled in the art can also change the implementation means of the positioning fixture 140 by a mechanical means to make the component position of the circuit board 120 to be inspected. Corresponds to the component positions of the standard board. In detail, a foolproof structure can be designed on the positioning fixture 140, so that both the standard circuit board and the circuit board 120 to be inspected can be installed in the positioning fixture 140 in the same direction to ensure the standard circuit board and the circuit to be detected. The component positions of the board 120 correspond to each other.

As shown in FIG. 1 , in the flowchart of the step of detecting the fault of the circuit board of the embodiment, the comparison between the thermal image of the circuit board 120 to be detected and the standard thermal image is performed by the same sampling and digitization. The process digitizes the analog data to compare the digital data of the thermal image of the printed circuit board 120 with the standard thermal image.

Please refer to Figure 1 and refer to Figure 3. In the circuit board fault detection method of the embodiment, the comparison result between the thermal image of the circuit board 120 to be detected and the standard thermal image is stored by a memory unit 182 and displayed through a display unit 184.

The thermal image comparison unit 180 of the fault detection method according to an embodiment of the present invention includes a sample hold circuit (SHC) and an analog-to-digital conversion circuit (ADC), which can convert the analog data of the thermal image into digital data and include A comparison circuit is made for comparison.

The present invention further discloses a fault detection method according to still another embodiment, in which the thermal image comparison unit 180 compares the thermal image to be detected with the standard thermal image (step 500). When the characteristics of the heat distribution of different components on the circuit board are utilized, the damage of the faulty circuit board is directly compared, and the detection efficiency is accelerated.

It should be noted that the number of damaged components may be single or more, depending on the number of components actually damaged by the faulty circuit board, and the order of comparison is not limited to the order of the above fault detecting methods.

For example, as shown in FIGS. 4A to 7B, respectively, a schematic diagram of a standard thermal image of a standard circuit board, and a schematic diagram of a thermal image of an abnormal component of the circuit board to be inspected. The thermal images of FIGS. 4A to 7B are compared by a thermal image comparison unit, and the detailed description thereof is as follows: a schematic diagram of a detection state of a transistor (MOS) of the circuit board as shown in FIGS. 4A and 4B, 4B is the case when the circuit board has multiple phases, when one of the transistors fails, because one transistor is not electrically connected normally, the two phases of the power supply only have one phase to perform work, causing another phase. The current increases and causes a significant increase in local temperature.

It is obvious from the heat distribution characteristics of the component that the temperature after the short circuit (as shown in FIG. 4B) is about 8 degrees higher than the temperature before the short circuit (as shown in FIG. 4A) to detect the heat to be compared. The image is different from the standard thermal image, and the corresponding component of the region is abnormal (short circuit), so that the detector can quickly and directly determine the component abnormality of the circuit board to be detected.

As shown in FIG. 5A and FIG. 5B, the detection state of the graphics processing unit (GPU) of the circuit board, and FIG. 5B shows that the temperature of the graphics processor is higher than that of the normal operation after the transistor short circuit breakdown of the circuit board. Reduced, and the graphics processor is unable to perform a protection mechanism for automatic power down.

Through the heat distribution characteristics of the component, it is apparent that the temperature after the short circuit (as shown in FIG. 5B) is reduced by about 45 degrees than the temperature before the short circuit (as shown in FIG. 5A) to detect the heat to be compared. The image is different from the standard thermal image, and the corresponding component of the region is abnormal (short circuit), so that the detector can quickly and directly determine the component abnormality of the circuit board to be detected.

As shown in Fig. 6A and Fig. 6B, the detection state of the capacitance of the circuit board is shown in Fig. 6B. When the capacitance of the circuit board is short-circuited, the display card loses the voltage except for 12 volts and 3.3 volts. Operation, resulting in a significantly lower operating temperature in the area than in normal operation.

It is obvious from the heat distribution characteristics of the element that the temperature after the short circuit (as shown in Fig. 6B) is reduced by about 10 degrees from the temperature before the short circuit (as shown in Fig. 6A) to detect the heat to be compared. The image is different from the standard thermal image, and the corresponding component of the region is abnormal (short circuit), so that the detector can quickly and directly determine the component abnormality of the circuit board to be detected.

The state of detection of the capacitance of the circuit board as shown in Figures 7A and 7B Figure 7B shows that when the capacitor of the board is short-circuited, the display card cannot operate due to the loss of voltage, resulting in a significant decrease in the operating temperature of the area compared to normal operation.

It is obvious from the heat distribution characteristics of the component that the temperature after the short circuit (as shown in Fig. 7B) is reduced by about 10 degrees from the temperature before the short circuit (as shown in Fig. 7A) to detect the heat to be compared. The image is different from the standard thermal image, and the corresponding component of the region is abnormal (short circuit), so that the detector can quickly and directly determine the component abnormality of the circuit board to be detected.

In summary, the fault detection method of the circuit board of the present invention and the fault detecting device can effectively improve the disadvantages of the conventional use, and can facilitate the operator to quickly and accurately perform the fault detection operation of the circuit board, and facilitate the comparison and judgment of the operator. The cause of the abnormal components of the board.

Although the embodiments of the present invention are disclosed above, it is not intended to limit the present invention, and those skilled in the art, regardless of the spirit and scope of the present invention, the shapes, structures, and features described in the scope of the present application. And the number of modifications may be made, and the scope of patent protection of the present invention shall be determined by the scope of the patent application attached to the specification.

100‧‧‧Fault detection device

120‧‧‧Device board to be tested

140‧‧‧ positioning fixture

160‧‧‧ Thermal Image Capture Unit

162‧‧‧Lens unit

164‧‧‧ temporary storage unit

180‧‧‧ Thermal Image Comparison Unit

182‧‧‧ memory unit

184‧‧‧ display unit

Step 200‧‧‧With the positioning fixture, the boards to be tested have the same detection point

Step 300‧‧‧ Capture the standard thermal image of the standard board with the thermal image capture unit

Step 400‧‧‧ Place the circuit board to be tested on the positioning fixture so that the position of the component of the circuit board to be inspected corresponds to the position of the component of the standard circuit board

Step 500‧‧‧Using the thermal image capturing unit to capture the thermal image to be detected on the circuit board to be inspected

Step 600‧‧‧Compared with standard thermal image by thermal image comparison unit

FIG. 1 is a flow chart showing the steps of a fault detecting method according to an embodiment of the present invention.

FIG. 2 is a block diagram of a fault detecting apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram of a fault detecting apparatus according to another embodiment of the present invention.

Fig. 4A is a schematic view showing a standard thermal image of the first aspect of the present invention.

Fig. 4B is a schematic view showing a thermal image of the abnormal element of the first aspect of the present invention.

Figure 5A is a schematic illustration of a standard thermal image of a second aspect of the invention.

Fig. 5B is a schematic view showing a thermal image of the abnormal element of the second aspect of the present invention.

Figure 6A is a schematic view of a standard thermal image of a third aspect of the present invention.

Fig. 6B is a schematic view showing a thermal image of the abnormal element of the third aspect of the present invention.

Figure 7A is a schematic view of a standard thermal image of a fourth aspect of the present invention.

Fig. 7B is a schematic view showing a thermal image of the abnormal element of the fourth aspect of the present invention.

Step 200‧‧‧With the positioning fixture, the boards to be tested have the same detection point

Step 300‧‧‧ Capture the standard thermal image of the standard board with the thermal image capture unit

Step 400‧‧‧ Place the circuit board to be inspected on the positioning fixture so that the position of the component of the circuit board to be inspected corresponds to the position of the component of the standard circuit board

Step 500‧‧‧Using the thermal image capturing unit to capture the thermal image to be detected on the circuit board to be inspected

Step 600‧‧‧ Compare the thermal image with the standard thermal image by the thermal image comparison unit

Claims (12)

A method for detecting a fault of a circuit board, comprising the steps of: taking a standard circuit board by using a thermal image capturing unit, and capturing a standard thermal image; placing a circuit board to be inspected on a positioning fixture to make the circuit to be detected The position of the plurality of components of the board corresponds to the positions of the plurality of components of the standard circuit board, and the positioning fixture has a foolproof structure, so that the standard circuit board and the circuit board to be tested can be installed only in the same direction. In the positioning fixture, to ensure that the standard circuit board and the component position of the circuit board to be inspected correspond to each other; the thermal image capturing unit captures the to-be-detected circuit board, and captures a thermal image to be compared; The thermal image comparison unit compares the thermal image of the to-be-compared thermal image with the standard thermal image by detecting a thermal distribution characteristic of the component to detect the component to be compared with the thermal image of the standard thermal image, and determining that the component is A faulty component. The method for detecting a fault of a circuit board according to claim 1, wherein the step of capturing the circuit board to be detected by the thermal image capturing unit is to capture the heat of the circuit board to be detected by a lens unit. image. The method for detecting a fault of the circuit board of claim 1, further comprising the step of: temporarily storing, by the thermal image temporary storage unit, the to-be-matched thermal image captured by the thermal image capturing unit and the standard Analog data for thermal images. The method for detecting a fault of a circuit board according to claim 3, wherein the method further comprises: digitizing the thermal image of the to-be-detected circuit board and the standard thermal image, and comparing the thermal image to the standard thermal image Analog data; and digital data of the thermal image and the standard thermal image of the test board. The method for detecting a fault of a circuit board according to claim 1, wherein the circuit board to be detected realizes the same detection point as the standard circuit board via an application. The method for detecting a fault of a circuit board according to claim 1, further comprising the step of: storing the comparison result of the thermal image comparison unit in a memory unit. The method for detecting a fault of a circuit board according to claim 1, further comprising the step of: displaying a comparison result of the thermal image comparison unit to a display unit. A fault detecting device is applicable to a circuit board to be inspected, wherein the circuit board to be tested is electrically provided with a plurality of components, and the fault detecting device comprises: a positioning fixture for a standard circuit board and the circuit board to be inspected Putting therein, so that the positions of the components of the circuit board to be inspected correspond to the positions of the plurality of components of the standard circuit board, and the positioning fixture has a foolproof structure, so that the standard circuit board and the circuit to be detected The boards can only be installed in the positioning fixture in the same direction to ensure that the component positions of the standard circuit board and the circuit board to be inspected correspond to each other; a thermal image capturing unit for capturing the standard circuit board and capturing a standard thermal image, and capturing the to-be-detected circuit board and capturing a thermal image to be compared; and a thermal image comparison unit electrically connecting the thermal image capturing unit, the thermal image comparison unit receiving and comparing The standard thermal image is compared with the thermal image to be compared, and the component to be compared to the thermal image is detected to be different from the standard thermal image. The fault detecting device of claim 8, wherein the thermal image capturing unit further comprises a lens unit for capturing the standard thermal image and the to-be-matched thermal image. The fault detecting device of claim 9, wherein the thermal image capture unit The device further includes a thermal image temporary storage unit for temporarily storing the analog data of the standard thermal image captured by the lens unit and the comparison thermal image. The fault detecting device of claim 8, further comprising a memory unit electrically connected to the thermal image comparison unit, wherein the memory unit stores the standard thermal image and the comparison thermal image. The fault detecting device of claim 8, further comprising a display unit electrically connected to the thermal image comparison unit, the display unit receiving and displaying the component of the standard thermal image different from the standard thermal image .