TWI487924B - Method and device for inspecting printed circuit board - Google Patents

Description

Printed circuit board detecting method and device thereof

The present invention relates to an optical detecting method and apparatus thereof, and more particularly to a method and apparatus for detecting a printed circuit board.

Printed circuit boards, such as hard printed circuit boards (PCBs) or flexible printed circuit boards (FPCs), require precise inspection procedures during the manufacturing process to check the correctness of the wiring, board conditions, and placement of components on the printed circuit board. Sex.

The manufacture of printed circuit boards is usually divided into several processes, which can be generally divided into the formation of lines, the production process for completing the conduction between lines (such as drilling, the fabrication of conduction lines), and the subsequent soldering and oxidation treatment. . Usually, in the entire manufacturing process of the circuit board, the detection of the line is completed when the line is produced in the previous stage, and the line is not tested again in the subsequent production process. Moreover, the subsequent production process will be A portion of the board is covered with a cover layer (eg, a solder mask), which causes the line under the cover to be shielded from being detected, and thus not in the manufacturing process of the back end of the printed circuit board. Then test the line.

However, in this subsequent production process, it is also possible to cause damage, defects, fractures, etc. of some lines due to collision, scratching or other various reasons, and the formation process of the cover layer during the anti-welding and anti-oxidation treatment. It may also be damaged by high temperature or other reasons on the printed circuit board. The circuit makes it impossible for the circuit on the printed circuit board to maintain the quality of the circuit in the previous stage to form the manufacturing process, thereby affecting the manufacturing yield of the printed circuit board.

One of the objects of the present invention is to perform line detection on a printed circuit board having a cover layer on a metal line when the printed circuit board is subjected to an appearance inspection program at a later stage of the manufacturing process.

Another object of the present invention is to obtain contour image data of the metal line without being affected by the cover layer on the metal line.

It is still another object of the present invention to provide a high efficiency and low cost line detection method and apparatus therefor.

To achieve the above and other objects, the present invention provides a method for detecting a printed circuit board, which is used for an appearance inspection program of a printed circuit board for detecting a printed circuit board having a cover layer on a metal line. The method includes: illuminating a printed circuit board to be tested with a first light source having a first wavelength band; obtaining first image data of a component of the first wavelength segment on the printed circuit board to be tested; and the first image data Performing a comparison procedure with a predetermined metal line image data, wherein the first wavelength band is a long wavelength and is a wavelength range of invisible light.

In an embodiment of the present invention, the method further includes: a visible light detecting step, comprising: illuminating the printed circuit board to be tested with a second light source having a second wavelength segment; and obtaining the printed circuit board to be tested a second image data of the components of the two wavelength segments; and a comparison process between the second image data and a predetermined printed circuit board appearance image data, wherein the second wavelength segment is a wavelength segment of visible light.

In an embodiment of the invention, the cover layer may be a solder resist layer, an organic protective film or a green paint layer or the like.

In an embodiment of the invention, the illumination of the first light source is incident on the printed circuit board to be tested at an oblique angle. Further, the first light source may be configured in an annular shape to provide the surrounding illumination light to the printed circuit board to be tested.

In order to achieve the above and other objects, the present invention provides a test apparatus for a printed circuit board, which is used for an appearance inspection program of a printed circuit board for detecting a printed circuit board having a cover layer on a metal line. The detecting device includes: a carrying platform for carrying the printed circuit board to be tested; a first light source generating device disposed above the carrying platform for illuminating the first light source having the first wavelength band Measuring a printed circuit board; a light source collecting device is disposed above the carrying platform for obtaining the first image data of the component of the first wavelength segment on the printed circuit board to be tested; and a computing host connecting the The light source collecting device is configured to compare the first image data with a preset metal line image data, wherein the first wavelength segment is a long wavelength band and is a wavelength segment of invisible light.

In an embodiment of the invention, the detecting device of the printed circuit board further comprises: a second light source generating device disposed above the carrying platform for illuminating the printing to be tested with a second light source having a second wavelength band a circuit board, wherein the light source collecting device obtains second image data of a component of the second wavelength segment on the printed circuit board to be tested, the computing host is configured to view the second image data and a predetermined printed circuit board The image data is subjected to an alignment program, and the second wavelength band is a wavelength band of visible light.

In an embodiment of the invention, the first wavelength band is a band of infrared light. The first wavelength band is preferably 850 nm to 950 nm.

Thereby, the present invention illuminates the printed circuit board by using the long-wavelength and the invisible light, so that even the metal line covered with the cover layer can clearly show its outline without the need for the line. An additional power-on heating procedure can be used to quickly obtain the contour of the covered metal line, eliminating the need to set the inspection neglect area or the complex and cumbersome comparison image on the metal line. The calculation program of the data greatly improves the detection efficiency and reliability.

110‧‧‧First light source generating device

120‧‧‧Second light source generating device

150‧‧‧Light source collection device

170‧‧‧Loading station

190‧‧‧ computing host

200‧‧‧Printed circuit board to be tested

CL‧‧‧ Coverage

F‧‧‧Line defect area

ML‧‧‧ metal lines

R‧‧‧Detecting the upper and lower ranges of the neglected area

PCB‧‧‧Printed circuit board

S101~S105‧‧‧Steps

S201~S205‧‧‧Steps

Figure 1a-1c is a schematic diagram showing the positional relationship between the metal lines and the cover layer on the printed circuit board.

Fig. 2 is a schematic view showing a printed circuit board detecting apparatus in an embodiment of the invention.

Fig. 3 is a schematic view showing a printed circuit board detecting apparatus in another embodiment of the present invention.

Figure 4 is a schematic cross-sectional view showing the first light source generating device of the present invention in an embodiment.

Figure 5 is a flow chart showing a method of detecting a printed circuit board in an embodiment of the present invention.

Figure 6 is a flow chart showing a method of detecting a printed circuit board in another embodiment of the present invention.

Figure 7a is the image data captured by the printed circuit board under visible light.

Figure 7b is the image data captured by the printed circuit board under long-wavelength invisible light.

Figure 8a is the image data of the printed circuit board with the broken line taken under visible light illumination.

Figure 8b is image data of a printed circuit board with a broken line taken under long-wavelength invisible illumination.

Figure 9a is an image of a printed circuit board having a darker cover layer under visible light illumination.

Figure 9b is image data taken by a printed circuit board having a darker cover layer under long-wavelength invisible light.

In order to fully understand the objects, features and effects of the present invention, the present invention will be described in detail by the following specific embodiments and the accompanying drawings. The known Auto Final Inspection, which can also be called the final appearance inspection machine, is an overall appearance inspection of the printed circuit board during the production process. The present invention implements a new detection technology in the appearance inspection program.

First, please refer to Figures 1a to 1c, which are schematic diagrams showing the positional relationship between the metal lines and the cover layer on the printed circuit board. Wherein, the metal line ML under the cover layer CL is not visible under the line detection of visible light, but for convenience of identification, the metal line ML to be shielded is shown by a broken line in the drawing.

Since the overlay layer CL has a problem of alignment accuracy in the process, the overlay layer CL formed on the printed circuit board is more or less "permitted" at the originally predetermined position. The shift affects the extent to which the underlying metal line ML is covered, thus causing the positional uncertainty of the metal line ML of each printed circuit board at the interface covering the cover layer CL.

In the case of Fig. 1a, when the metal line ML on the printed circuit board PCB is simplistic and linear, the covering edge of the cover layer CL is offset even if it is offset, for example, the upper and lower offsets. Line ML is still a straight line.

However, when the traces of the metal lines ML on the printed circuit board PCB are complicated, as shown in FIGS. 1b and 1c, the 1b and 1c diagrams each have the same metal line ML trace, but have different degrees of offset. The cover layer CL, the metal line ML exposed in these two offset states becomes quite complex Miscellaneous, and there are so many lines on the printed circuit board, it is quite difficult and time consuming to set a standard to make a set of algorithms suitable for various conditions.

Therefore, in the analysis and interpretation of optically detected image data, a set of algorithms is used to cover all "allowable" offset states, so that the metal lines ML of different degrees of exposure can be correctly interpreted. It will make the algorithm must be quite complicated and become quite difficult. In addition, because the detection program must be fast and efficient to increase productivity, the overly complex calculation judgment is not only time-consuming and error-prone; if the "detection neglect area" setting is used, such as The lower range R above the detection neglected area in Figures 1a to 1c allows the algorithm and detection to be fast and simple (due to the scope of the allowable offset being ignored in the detection), but the metal in the area is ignored. The line ML will not be detected, and once a defect occurs, it cannot be detected, thus causing an unreliable detection procedure.

Next, please refer to FIG. 2, which is a schematic diagram of a printed circuit board detecting apparatus in an embodiment of the present invention. The detecting device for the printed circuit board of the present invention is used for the appearance detecting program of the printed circuit board for detecting the printed circuit board which has been covered with the covering layer on the metal circuit, and the detecting device comprises: a carrying platform 170, The first light source generating device 110, the light source collecting device 150, and the computing host 190.

The carrier 170 is used to carry the printed circuit board 200 to be tested. The first light source generating device 110 is disposed above the carrying platform 170 for illuminating the printed circuit board 200 to be tested with a first light source having a first wavelength band, wherein the first wavelength segment is a long wavelength and is not The wavelength range of visible light. In addition, the first light source generating device 110 disposed above the carrying platform 170 is not limited to directly above the carrying platform 170, and the present invention can be applied to any space above the carrying platform 170, for example, when carrying When the stage is small, even if the first light source generating device 110 is located in the obliquely upward space of the stage 170, it still belongs to the category disposed above the stage 170.

The light source collecting device 150 is disposed above the carrying platform 170 for obtaining the first image data of the component of the first wavelength band on the printed circuit board 200 to be tested. The light source collecting device 150 disposed above the carrying platform 170 is also applicable to the aspect described in the preceding paragraph.

The computing host 190 is connected to the light source collecting device 150 for comparing the first image data with a preset metal line image data to generate a detection result of the printed circuit board 200 to be tested, wherein the preset metal The line image data is the configuration relationship diagram of the original design line.

Next, please refer to FIG. 3, which is a schematic diagram of a printed circuit board detecting apparatus in another embodiment of the present invention. The detecting device of the printed circuit board of the present invention, for example, may also be combined with the appearance final inspection machine, that is, as shown in FIG. 3, further comprising: a second light source generating device 120. The second light source generating device 120 is disposed above the carrying platform 170 for illuminating the printed circuit board 200 to be tested with a second light source having a second wavelength band. The second wavelength band is a wavelength range of visible light, and the light source collecting device 150 obtains second image data of the component of the second wavelength band on the printed circuit board 200 to be tested, and the computing host 190 The second image data is compared with a predetermined printed circuit board appearance image data. In the third embodiment, the second light source generating device 120 is disposed above the first light source generating device 110 as an example. It should be understood by those skilled in the art that the present invention is not limited to this configuration, and the figure is only one type. For example, the configuration relationship between the various second light source generating devices 120 and the first light source generating device 110 can be applied to the present invention.

Next, please refer to FIG. 4, which is a cross-sectional view of the first light source generating device of the present invention in an embodiment. The first light source generating device 110 of the present invention may be a single configuration, a symmetric opposite configuration (as shown in FIG. 2) or a ring configuration as shown in FIG. 4, which may be provided. More charge The illumination source of the foot. The first light source generating device 110 of the present invention preferably enters the printed circuit board 200 to be tested at an oblique angle (as shown in FIGS. 2 and 4).

Next, please refer to FIG. 5, which is a flow chart of a method for detecting a printed circuit board according to an embodiment of the present invention. Based on the description of the above apparatus, the method for detecting a printed circuit board of the present invention is used for an appearance inspection program of a printed circuit board for detecting a printed circuit board having a cover layer on a metal line, the method comprising Step S101: illuminating the printed circuit board to be tested with the first light source having the first wavelength band, wherein the first wavelength segment is a wavelength segment of long wavelength and invisible light; and step S103: obtaining the printed circuit board to be tested The first image data containing the component of the first wavelength segment; and step S105: comparing the first image data with a preset metal line image data.

Further, the detection method of the present invention is combined with the detection of the final inspection machine, and the steps S101 to S105 are referred to as the invisible light detection step, and the subsequent visible light detection step can be performed simultaneously with the invisible light detection step. (If the configuration shown in Figure 3 is simultaneous for illumination and image capture), either perform the visible light detection step and then perform the invisible light detection step, or perform the invisible light detection step and then perform the visible light detection step. this invention. Preferably, the visible light detecting step is performed simultaneously with the invisible light detecting step. As shown in FIG. 6, the visible light detecting step includes: Step S201: illuminating the printed circuit board to be tested with the second light source having the second wavelength band Wherein the second wavelength segment is a wavelength segment of visible light; Step S203: obtaining second image data of the component on the printed circuit board to be tested that has the second wavelength segment; and step S205: comparing the second image data with a predetermined printed circuit board appearance image data.

The illumination method of the light source used in the method of the present invention is the same as that of the foregoing apparatus, and details are not described herein again.

The cover layer CL mentioned in the present invention may be a solder resist layer, an organic protective film (OSP) or other cover layer which must be covered on the metal line ML, for example, may be a green paint layer. Preferably, the first wavelength segment of the present invention selects a wavelength band of infrared light, and a wavelength band of 850 nm to 950 nm can be selected to match with a line scan camera as the light source collecting device 150 to achieve better image data capturing effect.

Next, please refer to Figures 7a and 7b. Figure 7a shows the image data captured by the printed circuit board under visible light. Figure 7b shows the image data of the printed circuit board under the long-wavelength invisible light. . In this way, the different results seen under the illumination of visible light and long wavelength invisible light can be clearly recognized. Compared with the image data of FIG. 7a, the image data of FIG. 7b can be used for the computing host to clearly distinguish the cover layer. The routing of the metal line ML under the CL, therefore, the present invention will enable the detection of the metal line in the procedure of the appearance inspection, and the detection is a metal with high reliability, high efficiency, and low cost. The line inspection program will enable the finished printed circuit board to meet high quality standards.

Next, please refer to Figures 8a and 8b. Figure 8a is the image data of the circuit with the disconnected circuit taken by the printed circuit board under visible light. Figure 8b is the printed circuit board at the long wavelength. See the image data of the disconnected line taken under the illumination of the light. As shown in the figure, under visible light, the line defect area F under the cover layer ML cannot be easily identified. In contrast to the long-wavelength invisible light, the line defect area F under the cover layer ML can be easily identified. .

Next, please refer to Figures 9a and 9b. Figure 9a shows the image data captured by the printed circuit board with a darker cover layer under visible light. Figure 9b shows the printing with a darker cover layer. The image data captured by the board under long-wavelength invisible light. As shown in the figure, even if the color of the cover layer is deeper and the metal line under the cover layer is hardly recognized under visible light irradiation, the metal line under the cover layer can be easily identified under the illumination of long wavelength invisible light. . Accordingly, the present invention can provide an accurate, fast, and efficient metal line detection procedure in the appearance inspection program of a printed circuit board, thereby greatly improving detection efficiency and reliability.

The invention has been described above in terms of the preferred embodiments, and it should be understood by those skilled in the art that the present invention is not intended to limit the scope of the invention. It should be noted that variations and permutations equivalent to those of the embodiments are intended to be included within the scope of the present invention. Therefore, the scope of protection of the present invention is defined by the scope of the patent application.

S101~S105‧‧‧Steps

Claims (16)

A method for detecting a printed circuit board for detecting an appearance of a printed circuit board for detecting a printed circuit board having a cover layer on a metal line, the method comprising: having a first wavelength band The first light source illuminates the printed circuit board to be tested; obtains the first image data of the component of the first wavelength segment on the printed circuit board to be tested; and compares the first image data with a preset metal line image data The program, wherein the first wavelength segment is a long wavelength and is a wavelength segment of invisible light. The detection method of claim 1, further comprising a visible light detecting step, the visible light detecting step comprising: illuminating the printed circuit board to be tested with a second light source having a second wavelength segment; and obtaining the printed circuit board to be tested a second image data containing the component of the second wavelength segment; and comparing the second image data with a predetermined printed circuit board appearance image data, wherein the second wavelength segment is a visible light wavelength segment . The method of claim 2, wherein the covering layer is at least one of a solder resist layer and an organic protective film. The method of detecting according to claim 2, wherein the covering layer is a green lacquer layer. The detecting method of claim 2, wherein the illumination of the first light source is incident on the printed circuit board to be tested at an oblique angle. The detecting method of claim 5, wherein the first light source is in an annular configuration to provide enclosed illumination light to the printed circuit board to be tested. The detection method according to any one of claims 1 to 6, wherein the first wavelength band is a band of infrared light. The detection method of claim 7, wherein the first wavelength band is 850 nm to 950 nm. A printing circuit board detecting device is used for an appearance detecting program of a printed circuit board for detecting a printed circuit board which has been covered with a covering layer on a metal circuit, and the detecting device comprises: a carrying platform for Carrying a printed circuit board to be tested; a first light source generating device is disposed above the carrying platform for illuminating the printed circuit board to be tested with a first light source having a first wavelength band; a light source collecting device is disposed at a first image data for obtaining the component of the first wavelength segment on the printed circuit board to be tested, and a computing host connected to the light source collecting device for the first image data and A predetermined metal line image data is subjected to an alignment program, wherein the first wavelength band is a wavelength band of long wavelength and invisible light. The detecting device according to Item 9 of the claim, which further comprises: a second light source generating device is disposed above the carrying platform for illuminating the printed circuit board to be tested with a second light source having a second wavelength band, wherein the light source collecting device obtains the printed circuit board to be tested a second image data of the component of the second wavelength segment, the computing host compares the second image data with a predetermined printed circuit board appearance image data, and the second wavelength segment is a visible light wavelength segment . The detecting device according to claim 10, wherein the covering layer is at least one of a solder resist layer and an organic protective film. The testing device of claim 10, wherein the covering layer is a green lacquer layer. The detecting device of claim 10, wherein the illumination light of the first light source generating device is incident on the printed circuit board to be tested at an oblique angle. The detecting device of claim 13, wherein the first light source generating device is in an annular configuration to provide enclosed illumination light to the printed circuit board to be tested. The detecting device according to any one of claims 9 to 14, wherein the first wavelength band of the first light source generated by the first light source generating device is a band of infrared light. The detecting device of claim 15, wherein the first wavelength band is 850 nm to 950 nm.