An accuracy evaluation method for an optical measuring instrument

Abstract

The present application discloses a method for evaluating the accuracy of an optical measuring instrument, which relates to the technical field of measuring devices and includes: obtaining a first area on a circuit board for thickness measurement; when the material of the first area is a substrate, respectively measuring the thickness of a plurality of prefabricated first standard parts by using an optical measuring instrument to obtain a first measurement value of each first standard part; comparing each first measurement value with the first standard value of the corresponding first standard part, and outputting a first evaluation result; when the material of the first area is copper foil, respectively measuring the thickness at each groove position in a prefabricated second standard part by using an optical measuring instrument to obtain a second measurement value at each groove position in the second standard part; comparing each second measurement value with the second standard value at the corresponding groove position in the second standard part, and outputting a second evaluation result. The present application can evaluate the reliability of the measurement results of the optical measuring instrument.

Description

Technical Field

[0001] This application relates to the technical field of measuring devices, and particularly relates to a method for evaluating the accuracy of an optical measuring instrument. Background Art

[0002] Generally, when an optical measuring instrument (such as a coordinate measuring machine, a marble measuring machine table) measures the thickness of an object, it mainly obtains the material thickness by using a pulse wave to penetrate the material and then detecting the wave after penetration, or the material thickness can be extracted by analyzing the reflectivity of the pulse wave reflected from the object surface. However, due to the different optical grasping abilities of different materials, when the optical measuring instrument measures objects of different materials, the measured results may have errors. Especially for a circuit board with at least two materials, the measurement error may affect the yield rate of the circuit board and even affect the normal operation of the circuit board. Summary of the Invention

[0003] This application aims to solve at least one of the technical problems existing in the prior art. For this purpose, this application proposes a method for evaluating the accuracy of an optical measuring instrument, which can evaluate the reliability of the measurement results of the optical measuring instrument.

[0004] This application provides a method for evaluating the accuracy of an optical measuring instrument, including:

[0005] Obtain a first area on the circuit board where thickness measurement is to be performed; wherein, the circuit board includes a substrate and copper foil;

[0006] When the material of the first area is the substrate, use an optical measuring instrument to measure the thickness of a number of pre-made first standard parts respectively, and obtain a first measurement value for each of the first standard parts; wherein, the thickness of each first standard part is different;

[0007] Compare each of the first measurement values with the first standard value of the corresponding first standard part respectively, and output a first evaluation result; wherein, the first standard value is the true thickness value of the first standard part;

[0008] When the material of the first area is copper foil, use an optical measuring instrument to measure the thickness at each groove position of a pre-made second standard part respectively, and obtain a second measurement value at each groove position of the second standard part; wherein, the depth of each groove is different;

[0009] Compare each of the second measurement values with the second standard value at the corresponding groove position of the second standard part respectively, and output a second evaluation result; wherein, the second standard value is the true thickness value of the second standard part at the groove position.

[0010] The accuracy evaluation method of the optical measuring instrument according to the embodiments of the present application has at least the following beneficial effects: determining the first area on the circuit board that needs to be measured for thickness, and judging the material of the first area. When the material of the first area is the substrate, thickness measurements are respectively performed on a number of pre-made first standard parts using the optical measuring instrument to obtain the first measurement value of each first standard part, and they are respectively compared with the first standard value of the corresponding first standard part, and a first evaluation result for evaluating the result reliability of the optical measuring instrument when measuring the substrate is output; when the material of the first area is copper foil, thickness measurements are respectively performed on each groove position of the pre-made second standard part using the optical measuring instrument to obtain the second measurement value of each groove position of the second standard part, and they are respectively compared with the second standard value of the corresponding groove position of the second standard part, and a second evaluation result for evaluating the result reliability of the optical measuring instrument when measuring copper foil is output. Before measuring the first area on the circuit board, the measurement accuracy of the optical measuring instrument is evaluated using the first standard part or the second standard part according to the material of the first area, so as to obtain the reliability of the measurement result when measuring the thickness of the first area, so as to avoid large errors in the measurement result caused by using an optical measuring instrument with low accuracy to measure the thickness of the circuit board.

[0011] According to some embodiments of the present application, the first standard part is made according to the following steps: attaching second plate parts to both side surfaces of the first plate part; wherein, the first plate part and the second plate part have the same size, and a number of stacking areas are spaced apart on the first plate part; different thickness plate part groups are placed at positions corresponding to the stacking areas on one of the second plate parts to form a multi-layer board; wherein, the plate part group includes at least one third plate part; pressing the multi-layer board; cutting at positions corresponding to the stacking areas of the pressed multi-layer board to obtain a number of first standard parts with different thicknesses.

[0012] According to some embodiments of the present application, the first plate material is a glass fiber epoxy board, and the second plate material and the third plate material are both semi-cured sheets.

[0013] According to some embodiments of the present application, the first standard value is obtained according to the following steps: measuring each of the first standard parts using a calibrated measuring tool to obtain the first standard value corresponding to each of the first standard parts.

[0014] According to some embodiments of the present application, measuring each of the first standard parts using a calibrated measuring tool to obtain the first standard value corresponding to each of the first standard parts includes: measuring the center position of each of the first standard parts using a calibrated measuring tool to obtain the first standard value corresponding to each of the first standard parts.

[0015] According to some embodiments of the present application, the pressing of the multilayer board includes: attaching copper foils to both side surfaces of the multilayer board; wherein the size of the copper foil is greater than or equal to the size of the second plate member; pressing the multilayer board and the copper foils; after the pressing is completed, tearing off the copper foils on both side surfaces of the multilayer board.

[0016] According to some embodiments of the present application, the comparing each of the first measurement values with the first standard value of the corresponding first standard member and outputting a first evaluation result includes: when the difference between the first measurement value and the first standard value of the corresponding first standard member is less than a preset first threshold, outputting a first evaluation result indicating that the measurement result is reliable; when the difference between the first measurement value and the first standard value of the corresponding first standard member is greater than or equal to the preset first threshold, outputting a first evaluation result indicating that the measurement result is unreliable.

[0017] According to some embodiments of the present application, the second standard member is produced according to the following steps: equally spacing and dividing a plurality of copper reduction regions on a copper clad laminate; performing copper reduction on the copper reduction regions on the copper clad laminate in sequence with the same copper reduction depth, and the number of copper reduction times for each copper reduction region increases sequentially with the arrangement order of the copper reduction regions, so that a plurality of grooves with different depths are formed on the copper clad laminate, forming the second standard member; wherein, the copper thickness of the copper clad laminate is greater than the depth of the groove in the last copper reduction region.

[0018] According to some embodiments of the present application, the second standard value is obtained according to the following steps: calculating the second standard value at the position of each groove in the second standard member according to the copper thickness of the copper clad laminate and the depth of each groove.

[0019] According to some embodiments of the present application, when the difference between the second measurement value and the second standard value at the corresponding groove position in the second standard member is less than a preset second threshold, outputting a second evaluation result indicating that the measurement result is reliable; when the difference between the second measurement value and the second standard value at the corresponding groove position in the second standard member is greater than or equal to the preset second threshold, outputting a second evaluation result indicating that the measurement result is unreliable.

[0020] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The additional aspects and advantages of the present application will become apparent and be readily understood in conjunction with the following description of the embodiments with reference to the accompanying drawings, wherein:

[0022] Figure 1 Flow chart of the accuracy evaluation method of the optical measuring instrument according to some embodiments of the present application;

[0023] Figure 2 Flow chart of the manufacturing steps of the first standard part according to some embodiments of the present application;

[0024] Figure 3 Flow chart of the manufacturing steps of the second standard part according to some embodiments of the present application;

[0025] Figure 4 Schematic diagram of the first standard part according to some embodiments of the present application;

[0026] Figure 5 Schematic diagram of the second standard part according to some embodiments of the present application. Detailed implementation manners

[0027] The embodiments of the present application are described in detail below. The examples of the embodiments are shown in the drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application.

[0028] In the description of the present application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0029] In the description of the present application, if the first and second are described only for the purpose of distinguishing technical features, it should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0030] In the description of the present application, unless otherwise clearly defined, words such as setting, installing, connecting, etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present application in combination with the specific content of the technical solution.

[0031] Referring to Figure 1 , the present application provides an accuracy evaluation method for an optical measuring instrument, including but not limited to steps S110 to S150:

[0032] Step S110: Obtain the first area on the circuit board for thickness measurement; wherein, the circuit board includes a substrate and copper foil;

[0033] Step S120: When the material of the first region is a substrate, use an optical measuring instrument to measure the thickness of a number of pre-made first standard parts respectively, and obtain the first measurement value of each first standard part; wherein, the thickness of each first standard part is different;

[0034] Step S130: Compare each first measurement value with the first standard value of the corresponding first standard part respectively, and output the first evaluation result; wherein, the first standard value is the true thickness value of the first standard part;

[0035] Step S140: When the material of the first region is copper foil, use an optical measuring instrument to measure the thickness at each groove position of the pre-made second standard part respectively, and obtain the second measurement value at each groove position of the second standard part; wherein, the depth of each groove is different;

[0036] Step S150: Compare each second measurement value with the second standard value at the corresponding groove position of the second standard part respectively, and output the second evaluation result; wherein, the second standard value is the true thickness value of the second standard part at the groove position.

[0037] Determine the first region on the circuit board that needs to be measured for thickness, and judge the material of the first region. When the material of the first region is a substrate, use an optical measuring instrument to measure the thickness of a number of pre-made first standard parts respectively, obtain the first measurement value of each first standard part, compare it with the first standard value of the corresponding first standard part respectively, and output the first evaluation result for judging the result reliability of the optical measuring instrument when measuring the substrate; when the material of the first region is copper foil, use an optical measuring instrument to measure the thickness at each groove position of the pre-made second standard part respectively, obtain the second measurement value at each groove position of the second standard part, compare it with the second standard value at the corresponding groove position of the second standard part respectively, and output the second evaluation result for judging the result reliability of the optical measuring instrument when measuring copper foil. Before measuring the first region on the circuit board, use the first standard part or the second standard part to evaluate the measurement accuracy of the optical measuring instrument according to the material of the first region, so as to obtain the reliability of the measurement result of the optical measuring instrument when measuring the thickness of the first region, so as to avoid large errors in the measurement result caused by using an optical measuring instrument with low accuracy to measure the thickness of the circuit board.

[0038] Refer to Figure 2 , it can be understood that the first standard part is made according to the following steps, which includes but is not limited to the following steps:

[0039] Step S210: Stick second plate parts on both side surfaces of the first plate part respectively; wherein, the sizes of the first plate part and the second plate parts are equal, and a number of stacking regions are divided at intervals on the first plate part;

[0040] Step S220: Place a set of plates with different thicknesses at the position of one of the second plates corresponding to the stacking area to form a multi-layer board; wherein, the set of plates includes at least one third plate.

[0041] Step S230: Press the multi-layer board.

[0042] Step S240: Cut the pressed multi-layer board at the position corresponding to the stacking area to obtain a number of first standard parts with different thicknesses.

[0043] In one embodiment, first prepare a first plate with a thickness of 1 mm and a size of 18 * 24 inches, and at the same time prepare two second plates with a nominal thickness of 0.075 mm and a size of 18 * 24 inches, and prepare a number of third plates. Specifically, prepare 6 third plates with nominal thicknesses of 0.057 mm, 0.075 mm, 0.101 mm, and 0.123 mm each. Refer to Figure 4 the schematic diagram on the left. There are twelve stacking areas, which are equally spaced and distributed in a 3 * 4 pattern on the surface of the first plate, that is, the first plate is divided into three rows, and each row is divided into four stacking areas. Place one third plate with a thickness of 0.057 mm, two third plates with a thickness of 0.057 mm, and three third plates with a thickness of 0.057 mm in the three stacking areas of the first column respectively; place one third plate with a thickness of 0.075 mm, two third plates with a thickness of 0.075 mm, and three third plates with a thickness of 0.075 mm in the three stacking areas of the second column respectively; place one third plate with a thickness of 0.101 mm, two third plates with a thickness of 0.101 mm, and three third plates with a thickness of 0.101 mm in the three stackings of the third column respectively; place one third plate with a thickness of 0.123 mm, two third plates with a thickness of 0.123 mm, and three third plates with a thickness of 0.123 mm in the three stacking areas of the fourth column respectively. After all the third plates are placed, a multi-layer board is formed, the multi-layer board is pressed, and the pressed multi-layer board is cut at the position corresponding to the stacking area, as Figure 4 shown in the schematic diagram on the right, to obtain 12 corresponding first standard parts with different thicknesses. The present application does not specifically limit the thickness selection of the first plate, the second plate, and the third plate.

[0044] It can be understood that the first plate is a fiberglass epoxy board, the second plate and the third plate are both prepregs, and the materials selected for the plates are the same as those of the substrate of the circuit board, achieving the same optical grasping ability and improving the reliability of the precision evaluation results.

[0045] It can be understood that the first standard value is obtained according to the following steps, which include but are not limited to the following steps:

[0046] Measure each first standard part with a calibrated measuring tool to obtain a first standard value corresponding to each first standard part.

[0047] For example, by using a calibrated micrometer to measure each first standard part and recording the first standard value corresponding to each first standard part, during the subsequent accuracy evaluation process, the first standard value corresponding to the first standard part can be directly obtained without re-measurement.

[0048] It can be understood that in the above steps of measuring the first standard part, it may include but is not limited to the following steps:

[0049] Measure the central position of each first standard part with a calibrated measuring tool to obtain a first standard value corresponding to each first standard part.

[0050] When laminating the multi-layer board in a laminating machine, since PP glue flow will occur in the second and third plates, measure the central position of each first standard part with a calibrated measuring tool to improve the accuracy of the first standard value, so as to improve the reliability of the measurement accuracy evaluation result of the optical measuring instrument.

[0051] It can be understood that in step S230, it may include but is not limited to the following steps:

[0052] Copper foils are pasted on both surfaces of the multi-layer board; the size of the copper foil is greater than or equal to the size of the second board;

[0053] Laminating the multi-layer board and the copper foil;

[0054] After laminating, tear off the copper foils on both surfaces of the multi-layer board.

[0055] When putting the multi-layer board into the laminating equipment for laminating, when the laminating environment temperature is too high, it is easy to cause the second and third plates to stick to the pressing plate of the laminating machine, resulting in damage to the first standard part. By pasting copper foils on both surfaces, it can play a protective role for the multi-layer board. After laminating, tear off the copper foils on both surfaces of the multi-layer board, and cut the multi-layer board at the position corresponding to the stacking area after laminating to obtain several corresponding first standard parts.

[0056] It can be understood that in step S130, it may include but is not limited to the following steps:

[0057] When the difference between the first measurement value and the first standard value of the corresponding first standard part is less than a preset first threshold, output a first evaluation result indicating that the measurement result is reliable.

[0058] When the difference between the first measurement value and the first standard value of the corresponding first standard part is greater than or equal to a preset first threshold, output a first evaluation result indicating that the measurement result is unreliable.

[0059] Among them, the first evaluation result includes that the measurement result is reliable and the measurement result is unreliable. The first threshold represents the maximum error value that can be accepted when measuring the thickness of the substrate, and this application does not limit it.

[0060] Refer to Figure 3 , it can be understood that the second standard part is manufactured according to the following steps, which include but are not limited to the following steps:

[0061] Step S310: Divide a plurality of copper-removing regions at equal intervals on the copper-clad laminate;

[0062] Step S320: Perform copper removal on the copper-removing regions on the copper-clad laminate in sequence with the same copper-removing depth, and the number of copper-removing times for each copper-removing region increases sequentially with the arrangement order of the copper-removing regions, so that a plurality of grooves with different depths are formed on the copper-clad laminate to form the second standard part; wherein, the copper thickness of the copper-clad laminate is greater than the depth of the groove in the last copper-removing region.

[0063] In one embodiment, refer to Figure 5 , first prepare a copper-clad laminate with a thickness greater than 1 mm, and its copper thickness needs to be greater than 2 ounces. Optionally, attach blue tape to both sides of the copper-clad laminate. In this embodiment, divide 12 copper-removing regions at equal intervals on the copper-clad laminate and distribute them in a 3*4 pattern on the surface of the copper-clad laminate at equal intervals, that is, divide the copper-clad laminate into three rows, and each row is divided into four copper-removing regions. Perform copper removal on the copper-removing regions on the copper-clad laminate in sequence with a copper-removing depth of 5 microns, and the number of copper-removing times for each copper-removing region increases sequentially with the arrangement order of the copper-removing regions, so that a plurality of grooves with different depths are formed on the copper-clad laminate. Specifically, as shown in the front view on the left in Figure 5 , perform one-time copper removal, two-time copper removal, three-time copper removal, and four-time copper removal on the copper-removing regions from right to left in the third row in sequence, perform five-time copper removal, six-time copper removal, seven-time copper removal, and eight-time copper removal on the copper-removing regions from right to left in the second row in sequence, and the first copper-removing region on the leftmost side of the first row is subjected to twelve-time copper removal. Among them, Figure 5 The right side shows the cross-sectional view of each row of the second standard part, so that 12 grooves with different depths are formed on the copper-clad laminate, and thus the copper-clad laminate is used as the second standard part.

[0064] It can be understood that the second standard value is obtained according to the following steps, which include but are not limited to the following steps:

[0065] According to the copper thickness of the copper-clad laminate and the depth of each groove, calculate the second standard value at each groove position in the second standard part.

[0066] It is understandable that in step S150, it includes but is not limited to the following steps:

[0067] When the difference between the second measurement value and the second standard value at the corresponding groove position in the second standard part is less than the preset second threshold, output a second evaluation result indicating that the measurement result is reliable;

[0068] When the difference between the second measurement value and the second standard value at the corresponding groove position in the second standard part is greater than or equal to the preset second threshold, output a second evaluation result indicating that the measurement result is unreliable.

[0069] Among them, the second evaluation result includes that the measurement result is reliable and the measurement result is unreliable. The second threshold represents the maximum error value that can be accepted when measuring the thickness of the copper foil, and this application does not limit it.

[0070] For the above steps S210 to S240 and steps S310 to S320, for the first standard part and the second standard part, general production materials and equipment in a printed circuit board factory can be used for production, with low cost and fast preparation speed. The first standard part or the second standard part within the sample range required for testing can be quickly produced. The deviation values generated by the first standard part and the second standard part produced by this method are acceptable within the production range, and can preferably simulate the board thickness range of the actual production board.

[0071] The embodiments of the present application have been described in detail above with reference to the accompanying drawings. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the present application.

Claims

1. A method for evaluating the accuracy of an optical measuring instrument, characterized in that, Including: Obtain a first area on the circuit board for thickness measurement; wherein, the circuit board includes a substrate and copper foil; When the material of the first area is the substrate, perform thickness measurement on a number of pre-made first standard parts respectively using an optical measuring instrument to obtain a first measurement value for each of the first standard parts; wherein, the thickness of each first standard part is different; Compare each of the first measurement values with the first standard value of the corresponding first standard part, and output a first evaluation result; wherein, the first standard value is the true thickness value of the first standard part; When the material of the first area is copper foil, perform thickness measurement at each groove position in a pre-made second standard part respectively using an optical measuring instrument to obtain a second measurement value at each groove position in the second standard part; wherein, the depth of each of the grooves is different; Compare each of the second measurement values with the second standard value at the corresponding groove position in the second standard part, and output a second evaluation result; wherein, the second standard value is the true thickness value of the second standard part at the groove position; Wherein, the first standard part is made according to the following steps: Attach second plate parts to both side surfaces of a first plate part; wherein, the first plate part and the second plate parts have the same size, and a number of stacking areas are spaced and divided on the first plate part; Place a plate part group with different thicknesses at the position of the second plate part corresponding to the stacking area to form a multi-layer board; wherein, the plate part group includes at least one third plate part; Press the multi-layer board; Cut at the position of the multi-layer board after pressing corresponding to the stacking area to obtain a number of first standard parts with different thicknesses; Wherein, the second standard part is made according to the following steps: Divide a number of copper reduction areas at equal intervals on a copper clad laminate; Perform copper reduction at the copper reduction areas on the copper clad laminate in sequence with the same copper reduction depth, and the number of copper reduction times for each copper reduction area increases sequentially with the arrangement order of the copper reduction areas, so that a number of grooves with different depths are formed on the copper clad laminate to form the second standard part; wherein, the copper thickness of the copper clad laminate is greater than the depth of the groove in the last copper reduction area.

2. The accuracy evaluation method of the optical measuring instrument according to claim 1, wherein, The first plate part is a glass fiber epoxy board, and the second plate parts and the third plate parts are all prepregs.

3. The accuracy evaluation method of the optical measuring instrument according to claim 2, characterized in that, The first standard value is obtained according to the following steps: Measure each of the first standard parts using a calibrated measuring tool to obtain the first standard value corresponding to each of the first standard parts.

4. The method for evaluating the accuracy of the optical measuring instrument according to claim 3, characterized in that The step of measuring each of the first standard parts using a calibrated measuring tool to obtain the first standard value corresponding to each of the first standard parts includes: Measure the center position of each of the first standard parts using a calibrated measuring tool to obtain the first standard value corresponding to each of the first standard parts.

5. The accuracy evaluation method of the optical measuring instrument according to claim 1, characterized in that, The step of pressing the multi-layer board includes: Attach copper foil to both side surfaces of the multi-layer board; wherein the size of the copper foil is greater than or equal to the size of the second plate part; Press the multilayer board and the copper foil together; After the pressing is completed, tear off the copper foil on both surfaces of the multilayer board.

6. The accuracy evaluation method of the optical measuring instrument according to claim 1, characterized in that, Comparing each of the first measurement values with the first standard value of the corresponding first standard part and outputting a first evaluation result, including: When the difference between the first measurement value and the first standard value of the corresponding first standard part is less than a preset first threshold, output a first evaluation result indicating that the measurement result is reliable; When the difference between the first measurement value and the first standard value of the corresponding first standard part is greater than or equal to the preset first threshold, output a first evaluation result indicating that the measurement result is unreliable.

7. The accuracy evaluation method of the optical measuring instrument according to claim 1, wherein, The second standard value is obtained according to the following steps: Based on the copper thickness of the copper clad laminate and the depth of each groove, calculate the second standard value at each groove position in the second standard part.

8. The accuracy evaluation method of the optical measuring instrument according to claim 1, characterized in that Comparing each of the second measurement values with the second standard value at each corresponding groove position in the second standard part and outputting a second evaluation result, including: When the difference between the second measurement value and the second standard value at the corresponding groove position in the second standard part is less than a preset second threshold, output a second evaluation result indicating that the measurement result is reliable; When the difference between the second measurement value and the second standard value at the corresponding groove position in the second standard part is greater than or equal to the preset second threshold, output a second evaluation result indicating that the measurement result is unreliable.

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