A method for simultaneously etching multiple depths of a lead frame

Abstract

The present invention relates to the technical field of lead frame fabrication, and more specifically, to a method for simultaneously etching a lead frame at multiple depths. A resist dry film is disposed on a substrate, and a resist pattern is provided on the resist dry film. The resist pattern is designed so that different etching areas on the same dry film have different numbers and lengths of etching gaps. This allows the dry film to be etched into areas of varying depths after a single exposure-development-etching operation. This method allows for the precise and efficient manufacture of lead frame products with two different half-etch depths using a single etching operation, addressing the high cost, low precision, and low efficiency of traditional processes.

Description

Technical Field

[0001] The present invention relates to the technical field of lead frame preparation, and in particular to a method for synchronously etching a lead frame to multiple depths. Background Art

[0002] In semiconductor leadframe manufacturing, half-etching is a key process for forming conductive circuits and structures. When a single leadframe has different depth requirements for different areas, traditional processes require multiple etchings to meet the requirements. Specifically, each etching corresponds to an etching depth, and after multiple etchings, leadframes of different depths are etched out. Before each etching, operations such as lamination, exposure, and development are required. The resist pattern on the dry film during the lamination step also needs to be redesigned, tested, and adjusted according to the depth requirements. In other words, each etching requires a new resist pattern, and the resist pattern needs to be tested and adjusted multiple times during design. When etching multiple times, the number of operations for designing, testing, and adjusting the resist pattern doubles accordingly. This results in an overly cumbersome preparation process and low leadframe preparation efficiency.

[0003] For example, a half-etched lead frame structure and a manufacturing method thereof disclosed in publication number CN110896064A, the manufacturing method of the half-etched lead frame proposed has the following defects:

[0004] High cost: Repeated lamination, exposure, and development processes result in more than 30% waste of materials (dry film, etching solution);

[0005] Insufficient precision: Multiple alignment errors accumulate, and the half-etching depth error reaches 20μm;

[0006] Low efficiency: Two etchings require repeated lamination, exposure, development, and etching, which extends the production cycle by 40%. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for synchronously etching a lead frame to multiple depths.

[0008] The technical solution adopted by the present application to solve its technical problems is: a method for synchronously etching a lead frame at multiple depths, wherein a resist dry film is provided on a substrate, and a resist pattern is provided on the resist dry film. When designing the resist pattern, on the same resist dry film, different etching areas correspond to different numbers and lengths of etching gaps, so that after one exposure-development-etching process, the resist dry film can be etched into etching areas of different depths.

[0009] The resist pattern design comprises the following steps:

[0010] S1: Determine each etching area and its corresponding etching requirements;

[0011] S2: Determine the reference etching area;

[0012] S3: Determine the side etching length corresponding to the reference etching area;

[0013] S4: Based on the side etching length, the number and length of etching gaps corresponding to the remaining etching area are designed, and adjustments are made through testing to complete the final resist pattern design.

[0014] The etching requirements include requirements for etching depth and etching length corresponding to the etching area.

[0015] The etching depth includes at least two depths.

[0016] In the step S2 , the etching depth requirements corresponding to the etching regions are sorted, and the maximum etching depth is determined. The etching region corresponding to the maximum etching depth is the reference etching region.

[0017] In the S3, conventional mold design is performed based on the etching requirements corresponding to the reference etching area, and then test and adjust are performed to determine the final reference etching area, and the side etching length is determined based on the final reference etching area. The design of the reference etching area is consistent with the design during conventional etching, and no further details are given here. The purpose of this step is to design the etching areas of different depths for the side etching length under conventional design conditions, so that the final anti-etching mold can etch different etching depths at one time.

[0018] The reference etching area corresponds to an etching gap.

[0019] The S4 includes the following sub-steps:

[0020] S4-1: Determine the corresponding etching gap length in the remaining etching area based on the resolution capability of the dry resist film;

[0021] S4-2: In the remaining etching area, the side etching length of a single etching area and the distance between adjacent etching gaps are set to the side etching length determined in S3;

[0022] S4-3: Calculate the number of gaps that should be set for a single etching area;

[0023] S4-4: Based on the values ​​set in S4-1 to S4-3, a test is performed to determine whether the actual etching depth and etching length meet the etching requirements. If so, the final resist pattern design is completed; otherwise, adaptive adjustments are made until the actual etching depth and etching length meet the etching requirements.

[0024] In S4-3, the calculation formula for the number of gaps is:

[0025] ;

[0026] Where N is the number of etching gaps within a single etching zone, W is the length of the etching zone, I is the distance between adjacent etching gaps within the same etching zone, and H is the length of a single etching gap. H is the minimum size required for dry film analysis. Etching gaps within the same etching zone are arranged at equal intervals.

[0027] The remaining etching areas in S4-4, the adaptive adjustment of the same etching area includes:

[0028] If the etching depth corresponding to the center line of a single etching gap is greater than the etching depth requirement corresponding to the etching area, the etching gap length is shortened to make the etching depth shallower; if the etching depth corresponding to the center line of a single etching gap is less than the etching depth requirement corresponding to the etching area, the etching gap length is enlarged to make the etching depth deeper;

[0029] If the distance between single adjacent etching gaps is smaller than the etching requirement of the etching depth corresponding to the etching region, the distance between adjacent etching gaps is reduced.

[0030] Compared with the prior art, this application has the following beneficial effects:

[0031] By designing resist patterns with varying gaps in the etched area, this application enables the precise and efficient manufacture of lead frame products with two or more different half-etch depths in a single etching operation, addressing the high cost, low precision, and low efficiency of traditional processes. This application simplifies the manufacturing process, replacing multiple repetitive processes with a single etching operation. This ensures precision, with a misalignment error of ≤±10μm, and optimizes manufacturing efficiency, completing production processing with a single lamination, exposure, development, and etching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Prepare a flow chart for a prior art lead frame;

[0033] Figure 2 A flow chart for preparing the lead frame for this application;

[0034] Figure 3 Flow chart for preparing resist pattern template;

[0035] Figure 4 A schematic diagram of etching results caused by a single etching gap length being ≥ the etching gap length of the reference etching area;

[0036] Figure 5 Schematic diagram of etching results caused by the distance between adjacent etching gaps 3 being greater than 2 times the side etching length of the etching area;

[0037] Figure 6 A schematic diagram of a situation in which adaptive adjustment is to be made;

[0038] Figure 7 Schematic diagram of two etching depth structures in the embodiment;

[0039] Figure 8 Two etching depth size settings in the embodiment.

[0040] In the figure: 1. Substrate; 2. Anti-etching dry film; 3. Etching gap. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0043] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] Reference Figure 1 In the preparation of existing lead frames, the resist pattern on each dry film only corresponds to one etching depth. To prepare etching areas of multiple depths, different dry films need to be used respectively, and the preparation can only be completed after repeating the dry film pressing-exposure-development-etching process.

[0045] Reference Figure 2 When preparing the lead frame of this application, a substrate 1 to be processed (such as copper) is selected, and the surface of the substrate 1 is first degreased, then pickled to remove the oxide layer, rinsed with clean water, and dried for use.

[0046] Pressing dry film: On the surface of the dry substrate 1, the dry film is applied to the substrate surface by hot pressing.

[0047] Exposure: Place the substrate coated with photoresist under a high-precision photolithography machine, and irradiate the preset pattern on the dry film to undergo polymerization reaction to form an anti-etching dry film.

[0048] Development: The exposed substrate is placed in a developer solution, which allows different areas of the metal surface to be exposed according to a preset pattern (i.e., the resist pattern).

[0049] That is, a resist pattern is provided on the resist dry film 2 , and in this embodiment, the number and length of etching gaps 3 of each resist pattern are different.

[0050] Etching: Based on the set spray pressure and board feed speed, the etching liquid penetrates the etching gaps 3 on the resist dry film 2 and etches the copper material. The number and length of etching gaps 3 in the resist pattern vary, resulting in different etching liquid dosages, ultimately achieving two different half-etch depths in a single etching process.

[0051] Film stripping: After etching, use alkaline solvent to remove the remaining dry resist film, and finally rinse with pure water and dry.

[0052] During a single etching session, while the external conditions, such as the etching solution parameters, spray pressure, and substrate thickness, are consistent, different product application scenarios and design requirements lead to two distinct post-etching thickness requirements. This difference directly results in significantly different etching volumes.

[0053] Based on the differences in post-etch thickness, and from the perspective of material removal principles, the required etching depths must be different. Therefore, it is necessary to etch at different depths simultaneously. The time T required to complete these two etching specifications must be the same. In other words, on the same production line, etching at different depths must be completed within the same time.

[0054] In an actual etching operation environment, the material thickness of the substrate 1 is consistent, and the external conditions such as the composition, pressure and etching time of the etching solution are the same. Therefore, by designing different etching gaps 3 and gap lengths, the flow rate of the etching solution per unit time can be controlled to achieve control of the etching rate, thereby etching different depths within the same time.

[0055] The present application differentially designs the etching gap 3 of the anti-etching dry film 2 to regulate the etching liquid flow rate and reaction rate, thereby simultaneously achieving different depths in a single etching.

[0056] Therefore, the design idea of ​​this application is as follows: a long etching gap 3 is set for the etching area with a high etching depth value, thereby increasing the etching liquid flow and the etching rate; while a short etching gap 3 is set for the etching area with a low etching depth value, thereby reducing the etching liquid flow and the etching rate. By setting the etching gap 3 and the number of etching gaps 3, the etching rate of different etching areas can be controlled, thereby ensuring that different etching depths can be etched synchronously. This process is like adjusting the size of the faucet switch, controlling the speed of the water flow through precise operation.

[0057] In practice, there's a particular concern: if the etching solution flows too slowly, the waste products from the etching reaction can't be removed promptly. These products accumulate in the etching area, disrupting the normal etching reaction and causing a deviation in the etching direction. This causes the etching reaction to no longer proceed solely vertically, but to extend laterally, ultimately leading to increased lateral etching. This lateral etching then etches the substrate 1 in the etched area, creating the varying depths required for final processing to wet the flank leadframe.

[0058] Furthermore, referring to Figure 3 , this application includes the following steps when designing the resist pattern:

[0059] S1: Determine each etching area and its corresponding etching requirements; the etching requirements include requirements for etching depth and etching length corresponding to the etching area.

[0060] The etching depth includes at least two depths.

[0061] S2: Determine a reference etching region; in S2, the etching depth requirements corresponding to each etching region are sorted, and the maximum etching depth is determined. The etching region corresponding to the maximum etching depth is the reference etching region.

[0062] S3: Determine the side etch length corresponding to the reference etch area; in S3, conventional mold design is performed based on the etching requirements corresponding to the reference etch area, followed by testing and adjustment to determine the final reference etch area, and the side etch length is determined based on the final reference etch area. The design of the reference etch area is consistent with the design during the conventional etching test and will not be further described here. The purpose of this step is to design the remaining etching areas of different depths based on the side etch length under conventional design conditions, so that the final anti-etching mold can be etched to different etching depths in one go.

[0063] The reference etching area corresponds to an etching gap 3 .

[0064] S4: Based on the side etching length, the number and length of etching gaps 3 corresponding to the remaining etching area are designed, and adjustments are made through testing to complete the final resist pattern design.

[0065] The S4 includes the following sub-steps:

[0066] S4-1: Determine the length of the corresponding etching gap 3 in the remaining etching area based on the resolution capability of the resist dry film 2;

[0067] S4-2: In the remaining etching area, the side etching length of a single etching area and the distance between adjacent etching gaps 3 are set to the side etching length determined in S3;

[0068] S4-3: Calculate the number of gaps that should be set in a single etching area; in S4-3, the calculation formula for the number of gaps is:

[0069] ;

[0070] Where N is the number of etching gaps 3 within a single etching area, W is the length of the etching area, E is the side etching length, I is the distance between adjacent etching gaps 3 within the same etching area, and H is the length of a single etching gap 3. H meets the minimum size for dry film analysis, ensuring uniform distribution of the etching solution and stable etching results. Etching gaps 3 within the same etching area are arranged at equal intervals.

[0071] S4-4: Based on the values ​​set in S4-1 to S4-3, a test is performed to determine whether the actual etching depth and etching length meet the etching requirements. If so, the final resist pattern design is completed; otherwise, adaptive adjustments are made until the actual etching depth and etching length meet the etching requirements.

[0072] The length of the etching gap 3 is set to be greater than the resolution accuracy threshold of the resist dry film 2 and smaller than the length of the etching gap 3 in the reference etching region.

[0073] The differentiated configuration of the length of the etching gap 3 and the distance between adjacent etching gaps 3 directly affects the etching amount and side etching width of each etching area, and needs to be dynamically adjusted based on actual test data.

[0074] For the remaining etching areas, in the same etching area, in actual tests, if the length of a single etching gap 3 is greater than or equal to the length of the etching gap 3 of the reference etching area, the boundary protection function of the anti-etching dry film 2 will fail, causing the etching depth of the etching area to tend to be consistent, and local differentiated etching cannot be achieved, such as Figure 4 shown.

[0075] If the distance between adjacent etching gaps 3 is greater than 2 times the side etching length of the etching area, the copper residue between the adjacent etching gaps 3 cannot be completely removed by the side etching process, and a raised defect will be formed in the etching area, causing the etching depth to exceed the standard. Figure 5 shown.

[0076] Based on this, in the remaining etching areas, in the same etching area, the length of a single etching gap 3 should be set smaller than the etching gap 3 length of the reference etching area, and the distance between adjacent etching gaps 3 should be less than or equal to 2 times the side etching length of the etching area.

[0077] In actual testing, adaptive adjustment needs to be made based on the etching depth of the corresponding position of the etched material. Further, in the remaining etching area, the adaptive adjustment in the same etching area specifically includes:

[0078] like Figure 6 As shown, if the etching depth corresponding to the center line of a single etching gap 3 is greater than the etching depth requirement corresponding to the etching area, the length of the etching gap 3 is shortened to make the etching depth shallower. Conversely, if the etching depth corresponding to the center line of a single etching gap 3 is less than the etching depth requirement corresponding to the etching area, the length of the etching gap 3 is expanded to increase the etching flow rate, so that the etching depth is deeper.

[0079] If the distance between single adjacent etching gaps 3 is less than the etching depth requirement corresponding to the etching area, the distance between adjacent etching gaps 3 is reduced (i.e., the shielding area), and the copper residue in the shielding area is eliminated through testing to ensure the uniformity of local etching.

[0080] Different etching processes (such as spray and immersion) have different etching capabilities (including side etching rate, uniformity, etc.). The adjustment of the resist mask size and gap parameters needs to be optimized in combination with the etching capability characteristics of the specific process (such as etching factor, lateral etching rate ratio).

[0081] Reasonable control of the distance between two adjacent etching gaps 3 and the length of the etching gap 3 can meet various half-etching depth requirements and process lead frames with various depth requirements.

[0082] Compared with the traditional multiple-etching process, this application omits multiple rounds of lamination, exposure and development and other pre-processes, and can reduce material and labor costs by 30%-40%. One-time etching reduces the accumulated errors caused by multiple positioning and alignment, and the precision error of the two etching depths can be controlled within ±5μm, significantly improving product consistency. The single-batch production cycle is greatly shortened, and compared with the multiple-etching process, production efficiency can be increased by more than 30%, which is more in line with the needs of large-scale and rapid production.

[0083] Dry film usage is reduced by 50%, etching solution consumption is reduced by 50%, labor hours are reduced by 40%, and alignment error is reduced to ±10μm (compared to ±20μm with traditional processes). Daily production capacity is increased by 30%-40%. (For a 300-meter copper strip, for example, a single machine processes approximately 14 hours, of which cleaning, lamination, and exposure take approximately 7 hours. The traditional process requires two lamination and exposure steps, totaling approximately 21 hours. This single machine processing time is increased by 3%, and the reduction in waiting time and flow time increases overall efficiency by approximately 40%.)

[0084] Example 1

[0085] Reference Figure 7-Figure 8 This embodiment is a wettable flank lead frame DFN4.5*3-14L product, and the substrate 1 is made of copper with a thickness of 0.200 mm.

[0086] The product includes two etching depths, corresponding to two etching areas. The etching requirements for each etching area are as follows:

[0087] Etching area 1: Etching depth A1 is required to be MIN 0.130 mm, and the corresponding etching area length W1 is required to be 0.190 ± 0.025 mm;

[0088] Etching area 2: The etching depth A2 is required to be 0.100 mm ± 0.025 mm, and the corresponding etching area length W2 is required to be 0.350 ± 0.025 mm.

[0089] If etching depth A1 > etching depth A2, the etching area is fixed as the reference etching area.

[0090] The initial mold design was based on the existing copper chlorate etching process capabilities, namely the resolution capability of the currently used dry film and the side etching capability of the etching. The A-series anti-etching dry film used had a thickness of 19μm, a stable resolution capability of 16μm, and a side etching size of 50μm. The initial mold design was carried out, and preliminary experimental testing was conducted on the benchmark etching area. Through the initial mold design, exposure, development, and etching process, preliminary experimental testing showed that at an etching pressure of 15 / 40PSI and an etching time of 4 minutes, the etching depth A1 was within the range of 0.133-0.140mm, meeting the etching requirements for etching area one. However, the length W1 of etching area one after etching exceeded the upper limit of the etching requirement. To ensure that W1 was within the range of 0.190±0.025mm, experimental testing showed that the side etching length E1 = 0.056mm met the W1 dimension requirement.

[0091] In preliminary experimental tests, the etching depth A2 of etching area 2 was greater than 0.130mm, which did not meet the design requirements for etching area 2. The etching solution flow rate can be controlled by adding a resist dry film masking design. When adjusting the design of the remaining etching area (in this example, etching area 2), the following settings are made:

[0092] The side etching length E2 of etching area 2 = the distance between two adjacent etching gaps in etching area 2 I2 = the side etching length E1 of etching area 1 = 0.056 mm;

[0093] The etching gap length H2 of the etching area 2 is set to 0.016 mm with reference to the resolution capability of the dry film used.

[0094] Refer to the formula to calculate the number of gaps that can be set in etching area 2 .

[0095] Based on the above size setting, the pattern mold is designed, and then the exposure-development-etching experimental test is carried out to confirm the actual size.

[0096] Based on the deviation between the actual size and the required etching size, the side etching length E2 and the spacing between two adjacent etching gaps I2 are adjusted. The adjustment of the side etching length E2 affects the length W2 of the etching area 2, and the spacing I2 between two adjacent etching gaps and the etching gap length H2 affect the etching depth A2.

[0097] Furthermore, in actual testing, when E2=0.056mm, the actual length of W2 is 0.4mm, exceeding the expected 0.350±0.025mm. By increasing the length of E2, side etching compensation is performed, that is, (0.4-0.35) / 2+0.056=0.081mm. When I2=0.073mm and H2=0.016mm, the etching depth A2 is controlled in the range of 0.100±0.010mm, meeting the design requirement of 0.100±0.025mm. Due to the adjustment of the length of the etching gap etching mask, the size of E2 is sacrificed here. When the test size E2=0.077mm, the actual length of W2 is 0.358mm, which meets the W2 length requirement. A2 also meets the etching depth requirement. Finally, the number of shielding gaps in the second etching area is set to 3 .

[0098] Example 2

[0099] This embodiment is a wettable wing lead frame DFN3*3-8L product, and the substrate 1 is made of copper with a thickness of 0.200 mm.

[0100] The product includes two etching depths, corresponding to two etching areas. The etching requirements for each etching area are as follows:

[0101] Etching area 1: consistent with the requirements of Example 1;

[0102] Etching area 2: The etching depth A2 is required to be 0.100 mm ± 0.025 mm, and the corresponding etching area length W2 is required to be 0.340 ± 0.025 mm.

[0103] If etching depth A1 > etching depth A2, the etching area is fixed as the reference etching area.

[0104] Some etching requirements in this embodiment are also the same as those in embodiment 1. Therefore, during actual testing, some parameters can be directly set with reference to the values ​​in embodiment 1, eliminating the need for multiple debugging and saving testing time.

[0105] Furthermore, this embodiment can directly use the parameters of Example 1 to perform preliminary mold design and conduct preliminary experimental testing on the reference etching area. Through preliminary mold design, exposure, development, and etching, preliminary experimental testing, at an etching pressure of 15 / 40 PSI and an etching time of 4 minutes, met the etching requirements of etching area 1. Experimental verification also confirmed that the undercut length E1 = 0.056 mm met the W1 dimension requirement.

[0106] The etching area 2 can also refer to the design parameters of Example 1 for preliminary testing. However, since the W2 length requirement of this embodiment is 0.340mm, which is 0.010mm shorter than that of Example 1, H is limited by the length of the dry film analysis and remains unchanged. Therefore, the E2 and I2 values ​​are adjusted, that is, E2=0.075mm, I=0.070mm, H=0.016mm. The test meets the W2 length requirement, and the etching depth of the etching area 2 meets the standard. Finally, the number of shielding gaps in the etching area 2 is set to 3. .

[0107] The above descriptions are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention specification under the concept of the present invention, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for synchronously etching a lead frame to multiple depths, wherein a resist dry film (2) is provided on a substrate (1), and a resist pattern is provided on the resist dry film (2), characterized in that: When the anti-etching pattern is designed, on the same anti-etching dry film (2), different etching areas correspond to different numbers of etching gaps (3) and different lengths of etching gaps (3), so that after a single exposure-development-etching process, the anti-etching dry film (2) can be etched into etching areas of different depths; The resist pattern design comprises the following steps: S1: Determine each etching area and its corresponding etching requirements; the etching requirements include the etching depth and etching length requirements corresponding to the etching area; S2: Determine the reference etching area; In said S2, the etching depth requirements corresponding to each etching area are sorted, and the maximum etching depth is determined. The etching area corresponding to the maximum etching depth is the reference etching area; S3: Determine the side etching length corresponding to the reference etching area; S4: Taking the side etching length as a reference, design the number of etching gaps (3) and the length of etching gaps (3) corresponding to the remaining etching area, perform tests and adjustments, and complete the final resist pattern design; The S4 includes the following sub-steps: S4-1: Determine the length of the corresponding etching gap (3) in the remaining etching area based on the resolution capability of the dry resist film; S4-2: In the remaining etching area, the side etching length in a single etching area and the distance between adjacent etching gaps (3) are set to the side etching length determined in S3; S4-3: Calculate the number of gaps that should be set in a single etching area; in S4-3, the calculation formula for the number of gaps is: ； Wherein, N is the number of etching gaps (3) in a single etching area, W is the length of the etching area, I is the distance between adjacent etching gaps (3) in the same etching area, H is the length of a single etching gap (3), and H satisfies the minimum size of dry film analysis; S4-4: Based on the values ​​set in S4-1 to S4-3, a test is performed to determine whether the actual etching depth and etching length meet the etching requirements. If so, the final resist pattern design is completed; otherwise, adaptive adjustments are made until the actual etching depth and etching length meet the etching requirements. The remaining etching areas in S4-4, the adaptive adjustment of the same etching area includes: If the etching depth corresponding to the center line of a single etching gap is greater than the etching depth requirement corresponding to the etching area, the etching gap length is shortened to make the etching depth shallower; if the etching depth corresponding to the center line of a single etching gap is less than the etching depth requirement corresponding to the etching area, the etching gap length is enlarged to make the etching depth deeper; If the distance between single adjacent etching gaps is smaller than the etching requirement of the etching depth corresponding to the etching region, the distance between adjacent etching gaps is reduced.

2. The method for simultaneously etching a lead frame at multiple depths according to claim 1, wherein: The etching depth includes at least two depths.

3. The method for simultaneously etching a lead frame at multiple depths according to claim 1, wherein: In S3 , conventional mold design is performed based on the etching requirements corresponding to the reference etching area, and then testing and adjustment are performed to determine the final reference etching area, and the side etching length is determined based on the final reference etching area.

4. The method for simultaneously etching a lead frame at multiple depths according to claim 3, wherein: The reference etching area corresponds to an etching gap (3).

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