Simplified test method for etching uniformity

Abstract

The invention relates to the field of etching uniformity testing methods, in particular to a simplified testing method for etching uniformity. Comprising the following steps: step 1, selecting single-sided substrate copper as a to-be-tested plate; step 2, carrying out pre-bending treatment on the single-sided substrate copper to obtain a warped plate to be detected; 3, selecting N warping plates to be tested for parallel testing; the single warping board to be measured is subjected to size measurement before etching, etching and size measurement after etching in sequence; the plate thickness before etching and the plate thickness after etching are recorded, and the etching amount and the etching uniformity are calculated and used for comprehensively evaluating the etching property of the to-be-tested plate; therefore, a simplified test method for etching uniformity is obtained.

Description

Technical Field

[0001] The present invention relates to the field of etching uniformity testing methods, and specifically to a simplified testing method for etching uniformity. Background Art

[0002] In the process of manufacturing a circuit board by the subtractive method, in order to achieve the required circuit pattern, the most important chemical treatment method is to remove the excess copper by etching. Etching, also known as photochemical etching, refers to the removal of the protective film in the area to be etched after exposure and development, and contacting the chemical solution during etching to achieve the effect of dissolution and corrosion, forming the required pattern.

[0003] Currently, a common problem in etching substrates in the prior art is that it is difficult to achieve uniform etching of the substrate. The edge of the substrate is etched faster than the central part of the substrate, and the lower surface is etched faster than the upper surface. Through some methods, the phenomenon of uneven etching can be improved to improve the etching uniformity of the entire board surface. Etching uniformity is a very important performance index in the etching process and needs to be tested regularly.

[0004] Currently, the conventional testing process for etching uniformity is as follows: Using a double-sided copper substrate, in order to evaluate the etching uniformity of the upper and lower sprays separately, the substrate needs to be covered with a protective film before testing to ensure that only one side is etched during etching. Perform single-sided exposure and development on the non-etching side, and then sequentially perform pre-etching size measurement, etching, post-etching size measurement and calculate the etching uniformity. The operation is relatively cumbersome. Moreover, the traditional etching uniformity can only reflect the ability of the equipment, but the actual products have warps in different directions and different curvatures, which will cause the chemical solution to accumulate, thus affecting the etching uniformity. At this time, the etching uniformity tested by a unified method cannot fully reflect the uniformity state of the product.

[0005] In view of the above situation, the present invention designs a new method, which not only greatly simplifies the operation, but also can highly simulate the actual etching uniformity of all different products. Summary of the Invention

[0006] The purpose of the present invention is to provide a simplified testing method for etching uniformity to solve the problems raised in the prior art.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A simplified testing method for etching uniformity includes the following steps:

[0009] Step 1: Select a single-sided copper substrate as the test board;

[0010] Step 2: Perform pre-bending treatment on the single-sided copper substrate to obtain a warped test board;

[0011] Step 3: Select N warped plates to be tested for parallel testing; each single warped plate to be tested is successively subjected to pre-etching dimension measurement, etching, and post-etching dimension measurement; record the plate thickness before etching and the plate thickness after etching, and calculate the etch amount and etching uniformity to comprehensively evaluate the etchability of the plate to be tested.

[0012] Preferably, the pre-bending treatment of the warped plate to be tested is obtained by treating with a jig having a radian; after the pre-bending treatment, the warping value is -1.0 mm to +2.0 mm.

[0013] In a further solution, a single-sided substrate copper is used. Since the ceramic does not react with the etching solution, the effect is equivalent to one side of the copper on the double-sided substrate copper being covered by a protective film, and there is no need to perform additional steps related to film pasting, exposure, and development.

[0014] Preferably, in the parallel testing, N≥8;

[0015] During the measurement of the dimensions before etching and after etching, a micrometer is used for measurement, and the number of measurement fixed positions for each single warped plate to be tested is ≥4 points.

[0016] In a further solution, a jig with an adjustable edge height and a radian is used to pre-bend the plate to be tested into a preset radian; when the plate to be tested is pre-bent, the plate to be tested is single-sided copper-clad, and after pre-bending, the plate to be tested will not rebound, which facilitates further adjustment of the warping value of the plate to be tested. In this solution, the warping value of the single-sided copper-clad is greater than that of the double-sided copper-clad in the prior art. Therefore, it is necessary to reduce the warping value of the single-sided copper-clad, and a cover plate can be used for pre-bending. If it is necessary to simulate different directions of single-sided substrate copper such as upward warping and downward warping, the single-sided substrate copper can be manually bent to the simulated opposite direction first and then pre-bent.

[0017] Preferably, during the etching process, the warped plate to be tested is sprayed with the etching solution from above and below, and the spraying pressure is 1.5 - 3.0 kg / cm 2 .

[0018] Preferably, the equivalent concentration of hydrochloric acid in the etching solution is 1.4 - 2.0 N; the conductivity of sodium chlorate in the etching solution is 15 - 70; the specific gravity of copper ions in the etching solution is 1.26 - 1.32, and this specific gravity value is the relative density with respect to water, with the density of water under standard conditions as the reference.

[0019] Preferably, the calculation formula for the etch amount is: plate thickness before etching - plate thickness after etching = etch amount; the calculation formula for the etching uniformity is (1 - standard deviation of etch amount / average value of etch amount) × 100% = etching uniformity.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. It can greatly simplify the test of etching uniformity; 2. It reduces the cost; 3. It can highly simulate the etching uniformity of all actual products. Description of the Drawings

[0022] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0023] Figure 1 It is the copper structure diagram of the single-sided substrate;

[0024] Figure 2 It is the actual use structure diagram of the fixture;

[0025] Figure 3 It is the pre-bending treatment diagram;

[0026] Figure 4 It is the size measurement diagram before etching;

[0027] Figure 5 It is the preparation diagram of the upper-spray single-sided substrate copper;

[0028] Figure 6 It is the preparation diagram of the lower-spray single-sided substrate copper;

[0029] Figure 7 It is the size measurement diagram after etching;

[0030] Figure 8 It is the schematic diagram of the measurement position. Detailed Embodiments

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0032] In the following embodiments, the equivalent concentration of hydrochloric acid in the etching solution is 1.9N; the conductivity of the etching solution including sodium chlorate is 25; the specific gravity of copper ions in the etching solution is 1.29.

[0033] Embodiment 1: A simplified test method for etching uniformity, including the following steps:

[0034] Step 1: As Figure 1 shown, select a single-sided substrate copper composed of 0.3 mm copper and 0.38 mm ceramic as the test board;

[0035] Step 2: As Figure 2 , Figure 3As shown, the single-sided substrate copper is pre-bent. After the pre-bending treatment, the post-pre-bending warpage value is 0.5 mm; a warpage test plate is obtained.

[0036] Step 3: S1: As Figure 8 shown, 8 warpage test plates are selected for parallel testing. Using a micrometer to measure, the measurement fixed positions of a single warpage test plate are 4 points.

[0037] S2: As Figure 4 shown, the dimensions of a single warpage test plate are measured before etching and the pre-etching plate thickness data is recorded.

[0038] S3: Take 8 warpage test side plates and spray the etching solution on them respectively with the copper side up and the ceramic side up. The spraying pressure is 2.2 kg / cm 2 , as Figure 5 , Figure 6 shown, and A1 - A8 and B1 - B8 are obtained respectively.

[0039] S4: As Figure 7 shown, the above-mentioned A1 - A8 and B1 - B8 are respectively measured for dimensions after etching and the post-etching plate thickness data is recorded.

[0040] S5: According to the calculation formula of etching amount: pre-etching plate thickness - post-etching plate thickness = etching amount, calculate the etching amount; according to the calculation formula of etching uniformity: (1 - standard deviation of etching amount / average value of etching amount) × 100% = etching uniformity, calculate the etching uniformity; which is used to comprehensively evaluate the etchability of the test plate.

[0041] Example 2: The process is basically the same as that of Example 1. A simplified test method for etching uniformity includes the following steps:

[0042] Step 1: Select a single-sided substrate copper combined with 0.3 mm copper and 0.38 mm ceramic as the test plate.

[0043] Step 2: Pre-bend the single-sided substrate copper. After the pre-bending treatment, the post-pre-bending warpage value is 2.0 mm; a warpage test plate is obtained.

[0044] Step 3: S1: Select 8 warpage test plates for parallel testing. Using a micrometer to measure, the measurement fixed positions of a single warpage test plate are 4 points.

[0045] S2: The dimensions of a single warpage test plate are measured before etching and the pre-etching plate thickness data is recorded.

[0046] S3: Take 8 warpage test side plates and spray the etching solution on them respectively with the copper side up and the ceramic side up. The spraying pressure is 2.2 kg / cm 2 , and A1 - A8 and B1 - B8 are obtained respectively.

[0047] S4: Measure the dimensions of the above A1 - A8 and B1 - B8 after etching and record the plate thickness data after etching;

[0048] S5: According to the calculation formula of etching amount, pre - etching plate thickness - post - etching plate thickness = etching amount, calculate the etching amount; according to the calculation formula of etching uniformity, (1 - standard deviation of etching amount / average value of etching amount) × 100% = etching uniformity, calculate the etching uniformity; it is used to comprehensively evaluate the etchability of the plate to be tested.

[0049] Example 3: The process is basically the same as that of Example 1. A simplified test method for etching uniformity includes the following steps:

[0050] Step 1: Select a single - sided substrate copper composed of 0.3 mm copper and 0.38 mm ceramic as the plate to be tested;

[0051] Step 2: Perform pre - bending treatment on the single - sided substrate copper. After the pre - bending treatment, the warpage value after pre - bending is 1.0 mm; obtain the warped plate to be tested.

[0052] Step 3: S1: Select 8 warped plates to be tested for parallel testing. Use a micrometer for measurement. The measurement fixed positions for a single warped plate to be tested are 4 points;

[0053] S2: Measure the dimensions of a single warped plate to be tested before etching and record the plate thickness data before etching;

[0054] S3: Take 8 warped side plates and spray the etching solution upward and downward respectively with the copper side up and the ceramic chip side up. The spraying pressure is 2.2 kg / cm 2 , and obtain A1 - A8 and B1 - B8 respectively;

[0055] S4: Measure the dimensions of the above A1 - A8 and B1 - B8 after etching and record the plate thickness data after etching;

[0056] S5: According to the calculation formula of etching amount, pre - etching plate thickness - post - etching plate thickness = etching amount, calculate the etching amount; according to the calculation formula of etching uniformity, (1 - standard deviation of etching amount / average value of etching amount) × 100% = etching uniformity, calculate the etching uniformity; it is used to comprehensively evaluate the etchability of the plate to be tested.

[0057] Comparative Example 1: Use a double - sided substrate copper and measure it with the existing technology. Specifically:

[0058] Step 1: Select a double - sided substrate copper composed of 0.3 mm copper, 0.38 mm ceramic, and 0.3 mm copper as the plate to be tested. The warpage value of the plate to be tested is 0.5 m. After pre - treatment before laminating, laminating, exposure, and development respectively, obtain the double - sided substrate copper A as the plate to be tested;

[0059] Step 2: S1: Select 8 test plates for parallel testing. Use a micrometer to measure. The measurement fixed positions for a single warped test plate are 4 points;

[0060] S2: Measure the size of a single test plate before etching and record the plate thickness data before etching;

[0061] S3: Take 8 warped side plates and spray etching solution on both sides from top and bottom respectively. The spray pressure is 2.2 kg / cm 2 , and obtain A1 - A8 and B1 - B8 respectively;

[0062] S4: Measure the sizes of the above A1 - A8 and B1 - B8 after etching respectively and record the plate thickness data after etching;

[0063] S5: According to the calculation formula of etching amount, plate thickness before etching - plate thickness after etching = etching amount, calculate the etching amount; according to the calculation formula of etching uniformity, (1 - standard deviation of etching amount / average value of etching amount) × 100% = etching uniformity, calculate the etching uniformity; used to comprehensively evaluate the etching property of the test plate.

[0064] Comparative Example 2: Use double-sided substrate copper and measure it with the existing technology. Specifically:

[0065] Step 1: Select double-sided substrate copper composed of 0.3 mm copper, 0.38 mm ceramic, and 0.3 mm copper as the test plate. The warpage value of the test plate is 2.0 mm. After pretreatment before film lamination, film lamination, exposure, and development respectively, obtain double-sided substrate copper A as the test plate;

[0066] Step 2: S1: Select 8 test plates for parallel testing. Use a micrometer to measure. The measurement fixed positions for a single warped test plate are 4 points;

[0067] S2: Measure the size of a single test plate before etching and record the plate thickness data before etching;

[0068] S3: Take 8 warped side plates and spray etching solution on both sides from top and bottom respectively. The spray pressure is 2.2 kg / cm 2 , and obtain A1 - A8 and B1 - B8 respectively;

[0069] S4: Measure the sizes of the above A1 - A8 and B1 - B8 after etching respectively and record the plate thickness data after etching;

[0070] S5: According to the calculation formula of etching amount, plate thickness before etching - plate thickness after etching = etching amount, calculate the etching amount; according to the calculation formula of etching uniformity, (1 - standard deviation of etching amount / average value of etching amount) × 100% = etching uniformity, calculate the etching uniformity; used to comprehensively evaluate the etching property of the test plate.

[0071] Comparative Example 3: Double-sided substrate copper was used and measured by the existing technology. Specifically:

[0072] Step 1: A double-sided substrate copper composed of 0.3 mm copper, 0.38 mm ceramic, and 0.3 mm copper was selected as the test board. The warpage value of the test board was 1.0 mm. After pre-treatment before film lamination, film lamination, exposure, and development, double-sided substrate copper A was obtained as the test board;

[0073] Step 2: S1: Eight test boards were selected for parallel testing. A micrometer was used for measurement, and the measurement fixed positions of a single warped test board were 4 points;

[0074] S2: The size of a single test board was measured before etching, and the board thickness data before etching was recorded;

[0075] S3: Eight warped side plates were taken, and the etching solution was sprayed on both sides up and down. The spraying pressure was 2.2 kg / cm 2 , and A1 - A8 and B1 - B8 were obtained respectively;

[0076] S4: The above A1 - A8 and B1 - B8 were respectively measured for size after etching, and the board thickness data after etching was recorded;

[0077] S5: According to the calculation formula of etching amount, board thickness before etching - board thickness after etching = etching amount, the etching amount was calculated; according to the calculation formula of etching uniformity, (1 - standard deviation of etching amount / average value of etching amount) × 100% = etching uniformity, the etching uniformity was calculated; it was used to comprehensively evaluate the etching property of the test board.

[0078] Detection experiment: The test data of Examples 1 - 3 and Comparative Examples 1 - 3 are as follows: (1) Board thickness before etching and after etching for up spraying: The experimental data records of board thickness before etching and after etching of A1 - A8: The results are shown in Tables 1, 5, 9, 13, 17, and 21; (2) Board thickness before etching and after etching for down spraying: The experimental data records of board thickness before etching and after etching of B1 - B8: The results are shown in Tables 2, 6, 10, 14, 18, and 22; (3) Etching amount: According to the calculation formula of board thickness before etching - board thickness after etching = etching amount, the etching amount was obtained, as shown in Tables 3, 7, 11, 15, 19, and 23; (4) Etching uniformity: According to the calculation formula of (1 - standard deviation of etching amount / average value of etching amount) × 100% = etching uniformity, the etching uniformity was obtained, as shown in Tables 4, 8, 12, 16, 20, and 24;

[0079] The test data of Example 1 are as follows:

[0080]

[0081] Table 1

[0082]

[0083] Table 2

[0084]

[0085]

[0086] Table 3

[0087] Upper spray Lower spray Maximum value 0.194 0.191 Minimum value 0.154 0.165 Standard deviation 0.009 0.007 Average value 0.175 0.177 Etching uniformity 95.0％ 96.0％

[0088] The test data of Example 2 are as follows:

[0089]

[0090] Table 5

[0091]

[0092] Table 6

[0093]

[0094]

[0095] Table 7

[0096] Upper spray Lower spray Maximum value 0.196 0.200 Minimum value 0.163 0.164 Standard deviation 0.009 0.009 Average value 0.179 0.178 Etching uniformity 94.8％ 94.9％

[0097] The test data of Example 3 are as follows:

[0098]

[0099] Table 9

[0100]

[0101] Table 10

[0102]

[0103]

[0104] Table 11

[0105] Upper spray Lower spray Maximum value 0.190 0.190 Minimum value 0.159 0.158 Standard deviation 0.006 0.008 Average value 0.177 0.174 Etching uniformity 96.9％ 95.4％

[0106] The test data of Comparative Example 1 are as follows:

[0107]

[0108] Table 13

[0109]

[0110] Table 14

[0111]

[0112]

[0113] Table 15

[0114] Upper spray Lower spray Maximum value 0.201 0.194 Minimum value 0.161 0.161 Standard deviation 0.010 0.009 Average value 0.178 0.176 Etching uniformity 96.9％ 95.4％

[0115] The test data of Comparative Example 2 in Table 16 are as follows:

[0116]

[0117] Table 17

[0118]

[0119] Table 18

[0120]

[0121]

[0122] Table 19

[0123] Upper spray Lower spray Maximum value 0.225 0.214 Minimum value 0.169 0.166 Standard deviation 0.009 0.011 Average value 0.176 0.180 Etching uniformity 94.7％ 93.7％

[0124] The test data of Comparative Example 3 in Table 20 are as follows:

[0125]

[0126] Table 21

[0127]

[0128] Table 22

[0129]

[0130]

[0131] Table 23

[0132] Upper spray Lower spray Maximum value 0.184 0.183 Minimum value 0.168 0.156 Standard deviation 0.004 0.007 Average value 0.177 0.172 Etching uniformity 97.8％ 95.9％

[0133] Table 24

[0134] Result analysis: From the above experimental data, it can be seen that this solution can highly simulate the etching uniformity of all actual products, greatly simplify the test of etching uniformity, and reduce the cost.

[0135] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A simplified test method for etching uniformity, characterized in that: The following steps are involved: Step 1: Select single-sided copper substrate as the board to be tested; Step 2: Pre-bend the single-sided substrate copper to obtain a warped test board; Step 3: Select N warped test boards for parallel testing; a single warped test board is sequentially subjected to pre-etching dimension measurement, etching, and post-etching dimension measurement; the board thickness before etching and after etching are recorded, and the bite amount and etching uniformity are calculated to comprehensively evaluate the etching properties of the test board.

2. A simplified test method for etching uniformity according to claim 1, characterized in that: The pre-bending treatment of the warping test plate is obtained by using a cambered fixture; after the pre-bending treatment, the warping value is -1.0 mm to +2.0 mm.

3. A simplified test method for etching uniformity according to claim 1, characterized in that: In parallel testing, N ≥ 8; During the measurement process of the dimension measurement before etching and the dimension measurement after etching, a micrometer is used for measurement, and the measurement fixed positions of the single warpage test board are ≥ 4 points.

4. A simplified test method for etching uniformity according to claim 1, characterized in that: During the etching process, the etching liquid is sprayed up and down on the warped test board, and the spray pressure is 1.5-3.0 kg / cm 2 .

5. A simplified test method for etching uniformity according to claim 4, characterized in that: The equivalent concentration of hydrochloric acid in the etching solution is 1.4-2.0N; the conductivity of sodium chlorate in the etching solution is 15-70; and the specific gravity of copper ions in the etching solution is 1.26-1.

32.

6. A simplified test method for etching uniformity according to claim 1, characterized in that: The calculation formula of the bite amount is: board thickness before etching-board thickness after etching=bite amount; the calculation formula of the etching uniformity is (1-standard deviation of the bite amount / average value of the bite amount)×100%=etching uniformity.

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