TWI763090B - Correction method for probe offset - Google Patents

Abstract

A method for calibrating probe offset, suitable for being implemented by a processing unit, provides a circuit board to be tested, the circuit board to be tested has a plurality of solder pads, and has a plurality of solder pads which can respectively expose a surface of the corresponding solder pads The actual metal area of the window area, and the actual metal area of the window area has a plurality of tie marks corresponding to the solder pads. An optical device is used to capture the puncture images and the outline images of the actual metal area of the window area. The tie mark images are superimposed, so that the outline images of the metal area of the actual window area are stacked on each other to form an intersection area. In the intersection area, a displacement amount from a center of the intersection area is calculated as a reference for the probe movement compensation.

Description

Correction method for probe offset

The present invention relates to a calibration method, in particular to a probe offset calibration method.

In the process of making a general circuit board, it is inevitable that there will be electrical defects such as open circuit or short circuit due to the manufacturing process or external factors. Therefore, it is necessary to conduct an electrical test on the circuit board through an electrical testing device to immediately detect the defective circuit board. Screened out.

When the circuit board is electrically tested in the electrical measuring device, it is mainly carried out through the electrical measuring jig in the electrical measuring device. For the probes, after the circuit board is placed under the electrical measuring jig and positioned, the probes of the electrical measuring jig are pinned toward the corresponding solder pads to test the electrical condition of the circuit board.

However, when the probes of the electrical measuring jig are pinned with the solder pads of the circuit board, it is often caused by inaccurate positioning, circuit board etching, window opening and expansion errors, design errors of the electrical measuring jig itself, or External factors such as the assembly error of the electrical measuring fixture installed on the electrical measuring device cause the probes not to be pinned exactly on the ideal positions of the corresponding pads. And affect the accuracy of the electrical test.

In order to make the probes can be accurately pinned on the ideal points of the pads, the existing improvement method is to stick a blue tape covering the pads on the circuit board, and then let the pads The probe is punctured towards the blue film, leaving a puncture mark on the blue film, and then the positional relationship between the puncture mark on the blue film and the solder pads is manually judged through a microscope, so as to know that electrical measurement and treatment are required. Only by adjusting the rotation angle or the translation distance can the probes be accurately pinned on the ideal positions of the solder pads.

However, manually judging the positional relationship between the tie marks on the blue film and the solder pads is not only time-consuming, but also prone to judgment errors.

Therefore, the purpose of the present invention is to provide a method for calibrating probe offset.

Therefore, the method for calibrating the probe offset of the present invention is suitable to be implemented by a processing unit, and includes providing a circuit board to be tested, the circuit board to be tested has a plurality of solder pads, and a plurality of solder pads that can be respectively corresponding The actual window area metal area exposed on a surface of the , and the actual window area metal area has a plurality of tie marks corresponding to the equivalent solder pads.

Capture the puncture images and the actual metal of the window area with an optical device A contour image of the range.

The tie mark images are superimposed, so that the outline images of the metal area of the actual window area are stacked on each other to form an intersection area.

In the intersection area, a displacement amount from a center of the intersection area is calculated as a reference for the probe movement compensation.

In addition, another method for calibrating probe offset of the present invention includes providing a circuit board to be tested, the circuit board to be tested has a plurality of bonding pads, and a plurality of bonding pads which can respectively expose a surface of the corresponding bonding pads. The actual metal area of the window area, and the actual metal area of the window area has a plurality of tie marks corresponding to the solder pads.

An optical device is used to capture the piercing mark images and the outline images of the actual metal area of the window area, and obtain a plurality of ideal tie point positions corresponding to the actual metal area of the window area.

According to the tie mark images and the ideal tie point positions, a rotation displacement value is obtained through matrix operation, and a plurality of new needle insertion positions are calculated according to the rotation displacement value.

The new pinning positions are superimposed, so that the outline images of the actual metal area of the window area are stacked on each other to form an intersection area.

In the intersection area, a displacement amount from a center of the intersection area is calculated as a reference for the probe movement compensation.

The effect of the present invention lies in that, by capturing the image of each tie mark and the outline image of the actual metal area of the window area by the optical device, the ideal tie points are obtained The position and the puncture mark images are used to obtain the new needle position, and then the processing unit is used to make the tie mark images or the new needle position alternately overlap, so that the outline images of the metal area of the actual window area are integrated into the intersection area. , so that the center is calculated in the intersection area for subsequent corrective movements of the probes.

1: Electrical measuring device

11: Electric measuring fixture

111: Probe

2: Image of the circuit board to be tested

20: New needle position

200: PCB to be tested

21: Tie Mark Image

22: Outline image of solder pad

23: Contour image of the metal range in the actual window area

230: Circular window area

231: Perimeter

24: Intersection area

241: Perimeter

25: Center

26: Safe needle penetration range

27: Intersection area of safe needle penetration range

28: Security Center

D: Error distance

d: predetermined distance

p: ideal tie point position

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: FIG. 1 is a schematic diagram illustrating the use of an electrical measuring device to a circuit to be tested in the method for correcting probe offset of the present invention The board is electrically tested; FIG. 2 is a schematic diagram illustrating a first embodiment of the probe offset correction method of the present invention; FIG. 3 is a schematic diagram illustrating the first embodiment based on a plurality of puncture images and a plurality of ideals A plurality of new pinning positions are obtained from the pinning point positions; FIG. 4 is a schematic diagram illustrating that the first embodiment superimposes these new pinning positions, so that the corresponding multiple actual window area metal range contour images are overlapped; FIG. 5 is a A schematic diagram, auxiliary FIG. 4 illustrates an intersection area obtained by contour images of the actual windowed metal areas of the first embodiment; FIG. 6 is a schematic diagram illustrating a second implementation of the probe offset correction method of the present invention For example, these tie marks images are superimposed, so that the corresponding multiple actual window area metal range contour images Overlapping; FIG. 7 is a schematic diagram, supplementary FIG. 6 illustrates an intersection area obtained by contour images of the actual windowed metal areas of the second embodiment; FIG. 8 is a schematic diagram illustrating the correction of probe offset according to the present invention A third embodiment of the method; FIG. 9 is a schematic diagram illustrating that the third embodiment superimposes the new pinning positions so as to overlap a plurality of safe pinning regions in the contour images of the corresponding metal regions of the actual window area. Fig. 10 is a schematic diagram, and auxiliary Fig. 9 illustrates the intersection area of a safe needle needle range obtained by overlapping the safety needle ranges of the third embodiment; Fig. 11 is a schematic diagram illustrating a method for correcting probe offset of the present invention The fourth embodiment superimposes the puncture marks images so as to overlap a plurality of safe needle puncture areas in the contour images of the corresponding metal areas of the actual window area; and FIG. 12 is a schematic diagram, which assists FIG. 11 to illustrate the fourth embodiment For example, the intersection area of a safe acupuncture range obtained by the overlapping of these safe acupuncture ranges.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are designated by the same reference numerals.

Referring to FIG. 1, the calibration method of the probe offset of the present invention is suitable for a circuit under test The board 200 is implemented before the electrical testing is performed by an electrical testing device 1 .

Generally speaking, the circuit board 200 under test has a plurality of circuit traces, a plurality of solder pads electrically connected to the circuit traces, and a solder mask covering the solder pads; wherein, the solder mask layer There are a plurality of actual window area metal regions that can expose a surface of the corresponding pad, and the electrical measuring device 1 includes an electrical measuring jig 11 having a plurality of probes 111 .

The circuit board 200 to be tested is disposed under the electrical measuring jig 11 of the electrical measuring device 1, so that the probes 111 are located at the positions of the solder pads at intervals, and the electrical measuring jig 11 is directed toward the electrical measuring jig 11 to be measured. The circuit board 200 is pressed together in the direction, so that the probes 111 are in electrical contact with the surfaces of the pads within the metal area of the actual window area, so that the circuit board 200 to be tested is electrically tested.

Since the probes 111 of the electrical measuring fixture 11 are in electrical contact with the solder pads of the circuit board 200 to be tested, the electrical The design error of the measuring jig 11 itself, or the assembly difference of the electrical measuring jig 11 to the electrical measuring device 1 and other external factors, cause the probes 111 to be offset without being exactly connected to the solder pads The electrical contact will affect the accuracy of the electrical test. Therefore, in the method for correcting the probe offset of the invention, when the circuit board 200 to be tested is installed in the electrical testing device 1 for electrical testing, the A calibration process is performed so that the probes 111 are indeed in electrical contact with the pads.

It should be noted that the solder mask will have a plurality of openings for exposing the solder pads In practice, the size of the windowed areas may be smaller than or equal to or larger than the pads. Therefore, in the calibration method of the probe offset of the invention, the actual metal area of the windowed area is expressed in the The opening area exposes the bonding pads for the probes 111 to be pinned. That is, if the windowed areas are greater than or equal to the pads and the pads are completely exposed, the actual metal area of the windowed area is the area of the pads; if the windowed areas are smaller than the pads or covered by Part of the pad, the actual metal area of the window area is equal to the part of the pad exposed in the window area.

The calibration method is to first paste a film layer such as blue tape (but not limited to blue) on the circuit board 200 to be tested, and let the film layer cover the solder exposed in the metal area of the actual window area. Then, the circuit board 200 to be tested with the film layer is placed under the electrical measuring fixture 11 in the electrical measuring device 1 to perform the calibration process; wherein, the blue film is pasted on the to-be-measured device 1 . The test circuit board 200 can optionally cover the actual metal area of the window area partially or completely.

In the case of the present invention, considering that there is an error between the metal range of the actual window area and the metal range of the theoretical center of the pad (wherein, the metal range of the theoretical center of the pad can be known from the design drawing), so the optical device captures the actual opening. After the outline image of the metal area of the window area, the probes 111 are respectively punctured at the center position of the metal area of the actual window area, and then it is further detected whether the positions of the plurality of punctures on the film layer are located in the actual window area. Within the metal range of the window area, it is determined whether the probes 111 can be respectively and accurately pinned on the surface of the pad within the actual metal area of the window area. It should be noted that, Because the piercing needle will pass through the film layer and leave tie marks on the metal area of the actual window area, it is also possible to use the tie marks left on the metal area of the actual window area after removing the film layer to judge the accuracy of the piercing. . Judging by the tie marks on the film layer, the difference is that optical imaging is easier to show the tie mark images left on the film layer.

Referring to FIG. 2 , a first embodiment of the method for calibrating probe offset according to the present invention, after the calibration process forms a plurality of punctures on the film layer, the film to be tested with the film layer is directly photographed through an optical device The circuit board image 2 is used to capture the tie marks images 21 on the film layer, the outline images 22 of the solder pads, and the outline images 23 of the metal area of the actual window area, the irregularity on the left side of FIG. 2 The shape shows that the contour image 23 of the metal area of the actual window area is smaller than the contour image 22 of the corresponding pad, and the contour image 23 of the actual metal area of the window area may be located at any position on the contour image 22 of the pad ( i.e. the two are not proportionally reduced shapes). The perfect circular window area on the right side of FIG. 2 shows that the outline image 22 of the pad is smaller than the perfect circular window area 230 , so the outline image 23 of the actual metal area of the window area is equal to the outline image 22 of the pad. , namely 22 (23) on the upper right side of FIG. 2 .

The ideal pinning position set in FIG. 2 is at a relative center inside the outline image 23 of the actual metal area of the window area, that is, the film can be analyzed through the optical device and a processing unit. The positions of the puncture marks 21 of the actual needles on the layer and the corresponding contour images 23 of the actual metal regions of the window regions can be used to obtain the ideal pinning point positions p corresponding to the actual metal regions of the window regions. to say It should be noted that the optical device is not particularly limited, as long as the images can be clearly captured, and the processing unit may be a device such as a computer that can process the images. It should be noted that in all the embodiments of the present invention, although it is assumed that the ideal tie point position p of the outline image 23 of the actual metal area of the window area is located at the relative center, in practice, the ideal can be designed according to the planning of the fixture designer The tie point position p is not only limited to the relative center.

If the ideal pinning point position p is located at the relative center, since the pins 111 are pinned according to the actual center position of the metal area of the opening area of the bonding pads, when there is a skew or a deviation between the pins 111 When the needle sticking process produces errors, although it can stick within the metal area of the window area and is located in the outline image 23 of the metal area of the window area, the position of the sticking mark image 21 may be shifted in different directions (as shown in Fig. 2), at this time, it can be processed by the processing unit.

Next, referring to FIG. 3 , according to the tie mark images 21 and the ideal tie point positions p, an optimal rotation displacement value is obtained through the matrix least square method, and according to the optimal rotation displacement value, the tie mark images are obtained from the 21 A number of new pinning locations are estimated 20 . It should be noted here that because the probes 111 are fixed on the same electrical measuring fixture 11 (see FIG. 1 ), when the electrical measuring fixture 11 is moved, the probes 111 move as a whole. , therefore, it is necessary to first obtain the ideal pinning point position p corresponding to the actual metal area of the window area, and then re-estimate the new pinning positions 20 so as to allow the probes 111 to move as a whole. Move the probes until the ideal pinpoint position p The subsequent steps of 111 are described below.

Referring to FIG. 2 and FIG. 3 , in this embodiment, the optical device captures the outline images 23 and the puncture images 21 of the metal area of the actual window area, and obtains the corresponding actual window area For the ideal pinning point position p of the metal area, a plurality of new pinning positions 20 are estimated from the pinning mark images 21 by means of matrix operation.

Referring to FIGS. 4 and 5 again, the processing unit superimposes the new pinning positions 20, so that the outline images 23 of the actual metal area of the window area are stacked on each other to form an intersection area 24, and in the intersection area In step 24, a displacement amount from a center 25 of the intersection area is calculated as a reference for the movement compensation of the probes 111, that is to say, the overlapping new needle insertion position 20 and the center 25 can be calculated through the processing unit The error distance D between them is the distance by which the electrical measuring fixture 11 needs to be translated, so that the probes 111 are tied on the center 25 . It should be noted that the center 25 in the intersection area 24 is the maximum value of the closest distance to the peripheral edge 241 of the intersection area 24 , and the center 25 needs to be located in the contour images of the actual metal area of the window area 23 (that is, after the probe is displaced, it needs to be actually stuck on the contour image 23 of the metal area of the window area to be able to conduct).

Referring to FIG. 6 and FIG. 7 , it is a second embodiment of the method for correcting probe offset according to the present invention. The difference from FIG. 4 and FIG. 5 is that this is an embodiment in which the puncture mark images 21 are superimposed. The outline images 23 of the metal area of the actual window area are stacked on each other to form an intersection area 24, and in the intersection area 24, a displacement from a center 25 of the intersection area is calculated as the probes 111 reference for motion compensation, that is, That is to say, the error distance D between the overlapped puncture mark image 21 and the center 25 can be calculated by the processing unit, so as to know the distance by which the electrical measuring jig 11 needs to be translated, so that the probes 111 can be punctured in the center 25 . 25 on the center. Similarly, the center 25 is in the intersection area 24 , that is, the maximum distance from the periphery 241 of the intersection area 24 , and the center 25 needs to be located on the outline image 23 of the actual metal area of the window area. (That is, after the probe is displaced, it needs to be actually stuck on the contour image 23 of the metal area of the window area to be able to conduct).

In FIGS. 4 to 7 , the translation direction of the electrical measuring jig 11 can be regarded as two points on a coordinate system by taking the center 25 and the new pinning positions 20 or the pinning marks images 21 as two points on a coordinate system. In other words, the center 25 can be regarded as the origin on the coordinate system to determine the relative positions of the new needle positions 20 or the puncture images 21 and the center 25 to know the electrical measuring jig 11 The direction of the translation.

Referring to FIG. 8 , the third embodiment of the probe offset correction method of the present invention is substantially the same as the first embodiment, the difference is that the puncture images 21 and the corresponding ones are captured through the optical device After the contour images 23 of the actual metal area of the window area, further image processing is performed on the contour images 23 of the actual metal area of the window area, which is mainly performed by the processing unit. Only after a safe needle penetration range 26 is found in the outline image 23, the subsequent image superimposition process is performed.

Referring to FIG. 8 , first, the perimeter 231 of each contour image 23 of the actual metal area of the window area is shrunk by a predetermined distance d on average to obtain the position in the actual window area. The safety pinning area 26 in the outline image of the metal area of the window area; then see FIG. 9 , and then the new pinning positions 20 are overlapped, so that the safety pinning areas 26 are stacked on each other to form an intersection area of the safety pinning range 27. See Figure 10 again. Similarly, in the intersection area 27 of the safe needle penetration range, calculate the displacement of a safety center 28 away from the intersection area 27 of the safe needle penetration range. Finally, the safety center 28 is calculated. The positions of the probes 111 are respectively applied to the outline images 23 of the metal area of the actual window area, and the electrical measuring fixture 11 is moved according to the safety centers 28 so that the probes 111 face the circuit board 200 to be tested (see 1) When pressing in the direction, they can be respectively tied on the safety centers 28; wherein, the safety center 28 is the maximum value of the shortest distance from the periphery of the intersection area 27 of the safety needle range, and the safety center 28 It needs to be located on the contour images 23 of the metal area of the actual window area (that is, the probe needs to be actually stuck on the contour image 23 of the metal area of the window area after displacement to be able to conduct).

Referring to FIGS. 11 and 12 , a fourth embodiment of a probe offset correction method according to the present invention is different from FIGS. 9 and 10 in that this is an embodiment in which the puncture mark images 21 are superimposed. It is equal to stacking the safety pinning ranges 26 to form an intersection area 27 of the safety pinning range, and calculating the displacement of a safety center 28 away from the intersection area 27 of the safety pinning range, wherein the safety center 28 is the distance from the safety center 28. The maximum value of the closest distance to the periphery of the intersection area 27 of the safe needle penetration area, and the safety center 28 needs to be located on the outline image 23 of the actual metal area of the window area (that is, the probe needs to be actually stuck on the metal area of the window area after displacement the contour image 23 of the range can be turned on).

It is worth mentioning that, in the embodiments of FIGS. 8 to 12 , the purpose of the safe needle penetration range 26 obtained by the average indentation of the peripheral edge 231 of the contour image 23 of the actual metal range of the window area 26 is when the When the probes 111 are pierced within the safe piercing range 26 of the metal range of the actual window area, it can avoid further errors caused by other human or external factors after the calibration process is performed, and ensure that the probes 111 is indeed pinned on the pads within the metal area of the actual window area; wherein, the predetermined distance d is determined by the implementer according to experience or the shape and size of the actual metal area of the window area.

In addition, it should be noted that the shapes of the outline images 22 of the solder pads and the outline images 23 of the actual metal area of the window area shown in the drawings of the present invention are only schematic, and the actual situation may be a circle or an ellipse. , square, or irregular shapes, but they are all suitable for the calibration method of the present invention, and when the probes 111 of the present invention are tied on the film layer, their corresponding positions are on the outline of the metal range of each actual window area. The puncture mark image 21 in the image 23 is shown as a schematic illustration. The probe offset correction method of the present invention is applicable to both two-wire or four-wire measurement methods, that is, regardless of the actual metal area of the window area There are one, two or a plurality of puncture images 21 of the contour image 23, and the correction principle is the same as the above, and is not repeated here.

To sum up, the present invention captures the tie mark images 21 and the outline images 23 of the actual metal area of the window area by using the optical device, and then obtains the ideal tie point positions p and the tie mark images 21 Find the new needle insertion position 20 to match the processing unit The new pinning positions 20 or the piercing mark images 21 are overlapped, so that the outline images 23 of the metal area of the actual window area are merged into the intersection area 24, so that the center 25 can be calculated in the intersection area 24; further The safety pinning range 26 is predetermined in the outline image 23 of the metal range of the actual window area, and the intersection area 27 of the safety pinning range is intersected to find the safety center within the intersection area 27 of the safety pinning range 28. It can also ensure that the probes 111 are indeed stuck on the pads within the metal range of the actual window area when additional errors are generated by other human or external factors. The calibration method of the present invention can calculate the center 25 or the safety center 28, so that the electrical measuring fixture 11 can move according to the centers 25 or the safety centers 28, so that when the probes 111 are pressed toward the circuit board 200 to be tested, it can ensure The probes 111 are indeed stuck on the solder pads within the metal range of the actual window area, so the object of the present invention can indeed be achieved.

However, the above are only examples of the present invention, and should not limit the scope of implementation of the present invention. Any simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the patent specification are still included in the scope of the present invention. within the scope of the invention patent.

2･････････････････････････ Image of the circuit board to be tested 20··········· New needle position 21････････････････････････････････ Image 22･････ Pad outline image 23··············································································································································································· 23 p ·············

Claims (10)

A method for calibrating probe offset, suitable for being implemented by a processing unit, the method for calibrating probe offset includes: providing a circuit board to be tested, the circuit board to be tested has a plurality of solder pads, and a plurality of The actual window area metal area exposed on a surface of the corresponding solder pad, and the actual window area metal area has a plurality of tie marks corresponding to the solder pads; an optical device is used to capture the tie mark images and the contour images of the metal area of the actual window area; a perimeter of each contour image of the metal area of the actual window area is shrunken by a predetermined distance to obtain a position within the contour image of the metal area of the actual window area. Safe needle puncturing range; superimpose the images of these puncturing marks, so that the boundaries of the safe needle puncturing ranges are stacked on each other to form an intersection area of the safe needle puncturing range; The displacement of a safe center in the intersection area of the range is used as a reference for the probe movement compensation. The method for calibrating probe offset according to claim 1, wherein a film is partially or fully covered on the circuit board to be tested, so that the probes of the electrical measuring fixture are pressed toward the circuit board to be tested combined, and the tie marks are formed on the film layer. The method for calibrating probe offset according to claim 1 or 2, wherein the safety center in the intersection area of the safe needle puncturing range is the maximum value of the closest distance to a circumference of the intersection area of the safe needle puncturing range , and the safety center needs to be located on the outline image of the metal area of the actual window area. The method for correcting probe offset according to claim 2, wherein the film layer is selected from blue films. A method for calibrating probe offset, suitable for being implemented by a processing unit, the method for calibrating probe offset includes: providing a circuit board to be tested, the circuit board to be tested has a plurality of solder pads, and a plurality of The actual window area metal area exposed on a surface of the corresponding solder pad, and the actual window area metal area has a plurality of tie marks corresponding to the solder pads; an optical device is used to capture the tie mark images and The contour images of the actual metal area of the window area are obtained, and a plurality of ideal tie point positions corresponding to the actual metal area of the window area are obtained; according to the tie mark images and the ideal tie point positions, through the matrix The rotation displacement value is obtained by calculation, and according to the rotation displacement value, a plurality of new needle insertion positions are calculated; the new needle insertion positions are superimposed, so that the outline images of the metal area of the actual window area are stacked on each other to form an intersection area ; and in the intersection area, a displacement amount from a center of the intersection area is calculated as a reference for the probe movement compensation. The method for calibrating probe offset according to claim 5, wherein a film is partially or completely covered on the circuit board to be tested, so that the probes of the electrical measuring fixture are pressed toward the circuit board to be tested combined, and the tie marks are formed on the film layer. The method for correcting probe offset according to claim 5 or 6, wherein the center is in the intersection area and is the maximum value of the closest distance to a periphery of the intersection area, and the center needs to be located in the actual Window area metal range wheel on the profile image. The method for calibrating probe offset according to claim 5 or 6, wherein one digit in the actual window area is obtained by shrinking the circumference of each contour image of the metal area of the actual window area by a predetermined distance For the safe puncturing range in the outline image of the metal area, when the new puncturing positions overlap, the boundaries of these safe puncturing ranges are stacked on each other to form an intersection area of the safe puncturing range, and in the intersection area of the safe puncturing range Calculate a displacement from a safe center of the intersection area of the safe needle penetration range. The method for calibrating probe offset according to claim 5 or 6, wherein the electrical measuring jig is moved according to the isocenters, so that when the probes are pressed toward the circuit board to be tested, they can correspond to Tie on these centers of the intersection area. The method for correcting probe offset according to claim 6, wherein the film layer is selected from blue films.

Images