CN104655653B - Method and apparatus for inspecting printed circuit board - Google Patents

Abstract

The invention discloses a printed circuit board detection method and equipment, which are used for appearance detection of printed circuit boards and for detecting printed circuit boards that have been covered with a covering layer on metal circuits. The first light source in the wavelength range irradiates the printed circuit board to be tested, and the first wavelength range is long wavelength and invisible light, and then the obtained first light source on the printed circuit board to be tested containing the component of the first wavelength range is The image data is compared with the default metal circuit image data. Thereby, the present invention can provide an accurate, fast and efficient metal circuit inspection process in the appearance inspection process of printed circuit boards, without the need to set a detection ignore area or Design complex and cumbersome algorithms for comparing image data.

Description

Inspection method and equipment for printed circuit board

technical field

The invention relates to an optical detection method and its equipment, in particular to a printed circuit board detection method and its equipment.

Background technique

Printed circuit boards, such as rigid printed circuit boards (PCB) or flexible printed circuit boards (FPC), require precise inspection procedures during the manufacturing process to check the wiring on the printed circuit board, the condition of the board, and the placement of each component. correctness.

The manufacture of printed circuit boards is usually divided into several processes. Generally speaking, it can be divided into the formation of lines, the production procedures to complete the conduction between lines (such as drilling, the production of conductive lines), and the subsequent solder and anti-soldering. oxidation treatment. Usually, in the entire manufacturing process of the circuit board, the detection of the circuit has been completed during the production of the circuit in the previous stage, and the circuit will not be tested again in the subsequent production process. Moreover, the subsequent production process will be in Some areas of the circuit board are covered with a cover layer (such as a solder mask), which will shield the lines under the cover layer from detection, and will not be detected again in the back-end production process of the printed circuit board. Check the line.

However, in the subsequent production process, some circuits may be damaged, defective, broken, etc. due to collisions, scratches, or other reasons, and the covering layer formation process performed during solder mask and anti-oxidation treatment It is also possible to damage the circuit on the printed circuit board due to high temperature or other reasons, so that the circuit on the printed circuit board may not be able to maintain the quality of the previous stage of the circuit formation manufacturing process, which will affect the manufacturing pass rate of the printed circuit board .

Contents of the invention

One object of the present invention is to further perform circuit inspection on the printed circuit board covered with a cover layer on the metal circuit during the appearance inspection process of the printed circuit board in the later stage of the manufacturing process.

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

Another object of the present invention is to provide a high-efficiency and low-cost line detection method and equipment thereof.

In order to achieve the above-mentioned purpose and other purposes, the present invention proposes a detection method for printed circuit boards, which is used for the appearance detection program of printed circuit boards, and is used to detect printed circuit boards that have been coated with a covering layer on metal circuits. The method includes: irradiating the printed circuit board to be tested with a first light source having a first wavelength band; obtaining first image data of components containing the first wavelength band on the printed circuit board to be tested; and using the first image data A comparison procedure is performed with the default metal line image data, wherein the first wavelength segment is a long wavelength segment and an invisible wavelength segment.

In one embodiment of the present invention, a visible light detection step is also included, and the visible light detection step includes: irradiating the printed circuit board to be tested with a second light source having a second wavelength band; obtaining the printed circuit board to be tested containing the second the second image data of the components of the wavelength band; and the procedure of comparing the second image data with the default printed circuit board appearance image data, wherein the second wavelength band is the wavelength band of visible light.

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

In one embodiment of the present 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 can also be arranged in a ring shape, so as to provide surrounding illumination light to the printed circuit board to be tested.

In order to achieve the above purpose and other purposes, the present invention further proposes a printed circuit board inspection device, which is used for the appearance inspection program of the printed circuit board, and is used to detect the printed circuit board that has been coated with a covering layer on the metal circuit. , the detection equipment includes: a carrying platform for carrying a printed circuit board to be tested; a first light source generating device configured above the carrying platform for irradiating the printed circuit board to be tested with a first light source having a first wavelength band a light source collection device, configured above the carrying platform, for obtaining the first image data of the component on the printed circuit board to be tested that contains the first wavelength band; and a computing host, connected to the light source collection device, for the A comparison procedure is performed between the first image data and the default metal line image data, wherein the first wavelength segment is a wavelength segment of long wavelength and invisible light.

In one embodiment of the present invention, the inspection equipment for printed circuit boards further includes: a second light source generating device, arranged above the carrying platform, for irradiating 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 second image data of the component of the second wavelength band on the printed circuit board to be tested, and the computing host performs a comparison program between the second image data and the default appearance image data of the printed circuit board , the second wavelength band is the wavelength band of visible light.

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

Thereby, the present invention utilizes long-wavelength and invisible light to irradiate the printed circuit board, so that even the metal circuit that has been coated with a cover layer can still clearly show its outline, and there is no need to modify the circuit. The outline of the covered metal line can be quickly obtained by performing an additional electric heating procedure, and it is no longer necessary to set a detection neglect area or design a complex and cumbersome ratio for the junction of the metal line with or without the covering layer. The calculation program for image data greatly improves the detection efficiency and reliability.

Description of drawings

1a-1c are schematic diagrams showing the positional relationship between the metal circuit and the covering layer on the printed circuit board.

FIG. 2 is a schematic diagram of a printed circuit board inspection device in an embodiment of the present invention.

FIG. 3 is a schematic diagram of a printed circuit board inspection device in another embodiment of the present invention.

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

FIG. 5 is a flow chart of a printed circuit board inspection method in an embodiment of the present invention.

FIG. 6 is a flowchart of a printed circuit board inspection method in another embodiment of the present invention.

Fig. 7a is the image data captured by the printed circuit board under the irradiation of visible light.

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

FIG. 8 a is the image data of a disconnected circuit captured by a printed circuit board under visible light irradiation.

FIG. 8b is the image data of the disconnected circuit captured by the printed circuit board under the irradiation of long-wavelength invisible light.

FIG. 9 a is image data captured under visible light irradiation of a printed circuit board with a darker covering layer.

FIG. 9 b is image data captured by a printed circuit board with a darker covering layer under long-wavelength invisible light irradiation.

Main component reference signs:

110 First light source generating device

120 second light source generating device

150 light collection device

170 carrying platform

190 computing host

200 printed circuit boards to be tested

CL cover

F line defect area

ML Metal Line

R detects the upper and lower ranges of the ignored area

PCB printed circuit board

S101～S105 steps

Steps from S201 to S205

detailed description

For fully understanding purpose of the present invention, feature and technical effect, hereby by following specific embodiment, in conjunction with accompanying drawing, the present invention is described in detail, as follows:

The appearance inspection of printed circuit boards, such as the existing automatic appearance inspection machine (Auto Final Inspection), also known as the appearance final inspection machine, is to carry out the overall appearance inspection of the printed circuit board in the later stage of production, and the present invention is based on this appearance inspection Implement new detection techniques in the program.

First, please refer to FIGS. 1 a to 1 c , 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 covering layer CL cannot be seen under the line inspection of visible light, but for the convenience of identification, the shielded metal line ML is shown by a dotted line in the drawing.

Due to the alignment accuracy problem of the cover layer CL in the manufacturing process, the cover layer CL formed on the printed circuit board will more or less have an "allowable" offset at the original predetermined position. The shift will affect the degree of coverage of the underlying metal lines ML, thus causing uncertainty in the position of the metal lines ML of each printed circuit board at the junction of the covering layer CL.

Taking Fig. 1a as an example, when the metal line ML on the printed circuit board PCB is relatively simple and linear, even if the covering edge of the cover layer CL shifts, such as up and down, the exposed metal line ML is still a straight line.

However, when the routing of the metal line ML on the printed circuit board PCB is more complicated, as shown in Figures 1b and 1c, Figures 1b and 1c respectively have the same metal line ML routing, but have different offsets. Layer CL, the metal line ML exposed in these two offset states becomes quite complicated, and there are so many lines on the printed circuit board, it is necessary to set a standard to make a set of algorithms applicable to various situations Detection will be difficult and time-consuming.

Therefore, as far as the analysis and interpretation of the image data of optical inspection is concerned, a set of algorithms should be used to cover all "permissible" offset states, so as to correctly interpret metal lines ML with different degrees of exposure. It will make the algorithm very complex and difficult. In addition, because the detection program must be fast and efficient to increase production capacity, overly complex calculation judgments are not only time-consuming but also prone to errors; The upper and lower ranges R of the detection ignore area in Figures 1a to 1c can make the algorithm and detection fast and simple (the range formed by ignoring the allowable offset during detection), but the metal line ML in the ignore area will not be detected, and once a defect occurs, it will not be detected, thus creating an unreliable inspection program.

Please refer to FIG. 2 , which is a schematic diagram of a printed circuit board inspection device in an embodiment of the present invention. The inspection equipment for printed circuit boards of the present invention is used for the appearance inspection program of printed circuit boards, and is used for inspecting printed circuit boards covered with a covering layer on metal circuits. A light source generating device 110 , a light source collecting device 150 and a computing host 190 .

The carrying platform 170 is used for carrying the printed circuit board 200 to be tested. The first light source generating device 110 is arranged above the carrying platform 170, and is used to irradiate the printed circuit board 200 to be tested with a first light source having a first wavelength band, wherein the first wavelength band is long wavelength and invisible light wavelength band. In addition, the first light source generating device 110 disposed above the carrying platform 170 is not limited to be directly above the carrying platform 170, as long as it is located in the space above the carrying platform 170, the present invention is applicable. For example, when the carrying platform When it is small, even though the first light source generating device 110 is located in the space obliquely above the carrying platform 170 , it still belongs to the category of being disposed above the carrying platform 170 .

The light source collection device 150 is disposed above the carrying platform 170 and is used for obtaining first image data of the components on the printed circuit board 200 to be tested that contain the components in the first wavelength band. Wherein, the light source collection 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, and is used for performing a comparison procedure between the first image data and the default metal circuit image data, so as to generate the detection result of the printed circuit board 200 to be tested, wherein the default metal circuit image data is It is the configuration diagram of the original design circuit.

Next, please refer to FIG. 3 , which is a schematic diagram of a printed circuit board inspection device in another embodiment of the present invention. The inspection equipment of the printed circuit board of the present invention, for example, can also be combined with the appearance final inspection machine, that is, as shown in FIG. 3 , it also includes: a second light source generating device 120 . The second light source generating device 120 is disposed above the carrying platform 170 for irradiating the printed circuit board 200 to be tested with a second light source having a second wavelength band. Wherein, the second wavelength band is the wavelength band of visible light, the light source collection device 150 obtains the 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 takes the second image The data is compared with the default printed circuit board appearance image data. Wherein, FIG. 3 takes the second light source generating device 120 disposed above the first light source generating device 110 as an example. Those skilled in the art should understand that the present invention is not limited to this configuration, and this figure is only an example. The arrangement relationship between various second light source generating devices 120 and the first light source generating device 110 is applicable to the present invention.

Please refer to FIG. 4 , which is a schematic cross-sectional view of the first light source generating device in an embodiment of the present invention. The first light source generating device 110 of the present invention can be a single configuration, a symmetrical opposite configuration (as shown in FIG. 2 ) or a ring configuration as shown in FIG. 4 , and the ring configuration will provide more sufficient of light source. Wherein, the first light source generating device 110 of the present invention can preferably be incident on 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 flowchart of a printed circuit board inspection method in an embodiment of the present invention. Based on the description of the above-mentioned equipment, the detection method of the printed circuit board of the present invention is used for the appearance detection program of the printed circuit board, and is used to detect the printed circuit board that has been covered with a covering layer on the metal circuit. The method includes:

Step S101: Irradiating the printed circuit board to be tested with a first light source having a first wavelength band, wherein the first wavelength band is a long wavelength and wavelength band of invisible light;

Step S103: Acquiring first image data of the component on the printed circuit board to be tested that contains the first wavelength band; and

Step S105: Perform a comparison procedure between the first image data and the default metal line image data.

Further, the detection method of the present invention is combined with the detection of the final appearance inspection machine, and on the premise that the aforementioned steps S101 to S105 are called invisible light detection steps, the subsequent visible light detection steps can be performed simultaneously with the invisible light detection steps ( The configuration shown in FIG. 3 (where illumination and image capture are performed simultaneously), or the visible light detection step is performed first and then the invisible light detection step is performed, or the invisible light detection step is performed first and then the visible light detection step is performed, all can be applied to the present invention . Preferably, the visible light detection step can be carried out simultaneously with the invisible light detection step, as shown in Figure 6, the visible light detection step includes:

Step S201: Irradiating the printed circuit board to be tested with a second light source having a second wavelength band, wherein the second wavelength band is the wavelength band of visible light;

Step S203: Obtaining second image data of the component on the printed circuit board to be tested that contains the second wavelength band; and

Step S205: Perform a comparison procedure between the second image data and the default printed circuit board appearance image data.

The light source irradiation method adopted in the method of the present invention is the same as the description of the aforementioned equipment, and will not be repeated here.

The cover layer CL mentioned in the present invention can be a solder resist layer, an organic protective film (Organic Soldering Preservative, OSP) or other cover layers that must cover the metal lines ML, for example, a green paint layer. In the present invention, the first wavelength range is preferably the infrared wavelength range, and the wavelength range of 850nm-950nm can be selected to match with the line scan camera used as the light source collection device 150 to achieve better image data capture effect.

Next, please refer to FIGS. 7a and 7b. FIG. 7a is the image data captured by the printed circuit board under the irradiation of visible light, and FIG. 7b is the image data captured by the printed circuit board under the irradiation of long-wavelength invisible light. In this way, the different results seen under the irradiation of visible light and long-wavelength invisible light can be clearly identified. Compared with the image data in FIG. 7a, the image data in FIG. The wiring situation of the metal line ML, and therefore, the present invention will add the detection of the metal line to the program of the appearance inspection, and this detection is a metal line detection program with high reliability, high efficiency, and low cost , will make the final printed circuit board products reach high quality standards.

Next, please refer to FIGS. 8a and 8b. FIG. 8a is the image data of the disconnected circuit captured by the printed circuit board under the irradiation of visible light, and FIG. 8b is the image data of the printed circuit board captured by the long-wavelength invisible light. Image data of a disconnected line. As shown in the figure, under visible light, the line defect region F under the covering layer ML cannot be easily identified. On the contrary, under the irradiation of long-wavelength invisible light, the line defect region F under the covering layer ML can be easily identified. .

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

The present invention has been disclosed above with preferred embodiments, but those skilled in the art should understand that the embodiments are only for describing the present invention, and should not be construed as limiting the scope of the present invention. It should be noted that all changes and substitutions equivalent to this embodiment should be considered within the scope of the present invention. Therefore, the protection scope of the present invention should be determined by the contents defined in the claims.

Claims (14)

1. A circuit and an appearance detection method of a printed circuit board, characterized in that, the circuit and appearance detection program for a printed circuit board is used to detect a printed circuit board that has been coated with a cover layer on a metal circuit; Wherein, the method includes an invisible light detection step, and the invisible light detection step includes: Irradiating the printed circuit board to be tested with a first light source having a first wavelength band; Obtaining first image data of components containing the first wavelength band on the printed circuit board to be tested; and performing a comparison procedure on the first image data and the preset metal circuit image data, Wherein, the first wavelength band is a wavelength band of long wavelength and invisible light; Wherein, the method also includes a visible light detection step, and the visible light detection step includes: Irradiating the printed circuit board to be tested with a second light source having a second wavelength band; Obtaining second image data of components containing the second wavelength band on the printed circuit board to be tested; and performing a comparison procedure on the second image data and the preset printed circuit board appearance image data, Wherein, the second wavelength band is the wavelength band of visible light. 2 . The detection method according to claim 1 , wherein the covering layer is at least one of a solder resist layer and an organic protective film. 3 . 3. The detection method according to claim 1, characterized in that the covering layer is a green paint layer. 4. The detection method according to claim 1, wherein the irradiation of the first light source is incident on the printed circuit board to be tested at an oblique angle. 5 . The detection method according to claim 4 , wherein the first light source is configured in a ring shape to provide surrounding illumination light to the printed circuit board to be tested. 6 . 6. The detection method according to any one of claims 1 to 5, characterized in that, the first wavelength band is a wavelength band of infrared light. 7. The detection method according to claim 6, wherein the first wavelength range is 850nm-950nm. 8. A circuit and appearance inspection equipment for a printed circuit board, characterized in that it is used for a circuit and appearance inspection program for a printed circuit board, to detect a printed circuit board that has been coated with a covering layer on a metal circuit, The testing equipment includes: The carrying platform is used to carry the printed circuit board to be tested; a first light source generating device, configured above the carrying platform, for irradiating the printed circuit board to be tested with a first light source having a first wavelength band; a light source collecting device, arranged above the carrying platform, for obtaining first image data of components containing the first wavelength band on the printed circuit board to be tested; and a computing host, connected to the light source collection device, for performing a comparison procedure between the first image data and the preset metal circuit image data, Wherein, the first wavelength band is a wavelength band of long wavelength and invisible light; Among them, the detection equipment also includes: The second light source generating device is arranged above the carrying platform, and is used to irradiate the printed circuit board to be tested with a second light source having a second wavelength band, Wherein, the light source collection device obtains the second image data of the component of the second wavelength band on the printed circuit board to be tested, and the computing host performs a comparison procedure between the second image data and the preset appearance image data of the printed circuit board. , the second wavelength band is the wavelength band of visible light. 9. The detection device according to claim 8, wherein the covering layer is at least one of a solder resist layer and an organic protective film. 10. The detection device according to claim 8, wherein the covering layer is a green paint layer. 11. The testing device according to claim 8, 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. 12 . The testing device according to claim 11 , wherein the first light source generating device is arranged in a ring shape to provide surrounding illumination light to the printed circuit board to be tested. 13 . 13. The detection device according to any one of claims 8 to 12, wherein the first wavelength band of the first light source generated by the first light source generating device is a wavelength band of infrared light. 14. The detection device according to claim 13, wherein the first wavelength range is 850nm˜950nm.