Super-thick copper PCB and manufacturing method thereof

Abstract

The invention provides an ultra-thick copper PCB and a manufacturing method thereof, and belongs to the technical field of printed circuit boards, and the method comprises the steps: pasting photosensitive films on a pressing surface and a non-pressing surface of a copper foil, and carrying out the first pattern transfer; carrying out first etching on the press-fit surface and the non-press-fit surface of the copper foil; laminating two adjacent layers of copper foils subjected to first etching through prepregs to form a multi-layer board, pasting photosensitive films on two non-laminated surfaces of the multi-layer board, and performing second pattern transfer; second etching is carried out on the first etching positions of the two non-press-fit surfaces of the multi-layer board; the circuit board is manufactured by the method. According to the method, the double surfaces are etched for the first time, and then the non-laminated surface is etched for the second time, so that the ultra-thick copper foil is etched for three times, and the problems of serious lateral erosion and poor etching factor during one-time etching of the ultra-thick copper circuit board in the traditional process are obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit boards, and particularly to an ultra-thick copper PCB and a manufacturing method thereof. Background Art

[0002] Ultra-thick copper circuit boards generally refer to circuit boards with a copper foil thickness of more than 6 oz. Due to their high current-carrying capacity and excellent heat dissipation performance, ultra-thick copper circuit boards are widely used in high-current and high-voltage electronic devices such as power amplifiers, charging devices, inverters, vehicle lights, and automotive high-voltage modules.

[0003] However, there are many difficult-to-overcome problems in the traditional manufacturing method of ultra-thick copper circuit boards, especially for circuit boards with an inner copper thickness of more than 8 oz: First, when the circuit board is etched, side etching is likely to occur. The thicker the copper layer, the more serious the side etching and the worse the etching factor. This will cause the etched line width of the ultra-thick copper circuit board to become narrower and the line spacing to become larger, affecting the accuracy of the circuit. Second, when using a special structure of glass cloth in the prepreg lamination to fill the ultra-thick copper line spacing at one time, due to the insufficient resin flow layer on one side of this type of prepreg, it is difficult to completely fill the line spacing, and voids are likely to occur during lamination, thus affecting the reliability of the circuit board. Summary of the Invention

[0004] To overcome the problems existing in the related art, one of the objectives of the present invention is to provide a manufacturing method of an ultra-thick copper PCB. By first performing double-sided first etching and then non-lamination surface second etching, the ultra-thick copper foil is etched three times, significantly improving the problems of serious side etching and poor etching factor during one-time etching of ultra-thick copper circuit boards in the traditional process.

[0005] A manufacturing method of an ultra-thick copper PCB includes the following steps:

[0006] Apply photosensitive films to both the lamination surface and the non-lamination surface of the copper foil, and perform the first pattern transfer.

[0007] Perform the first etching on both the lamination surface and the non-lamination surface of the copper foil. Among them, the lamination surface is etched to a first preset etching depth, and the non-lamination surface is etched to a second preset etching depth.

[0008] Press the adjacent two layers of copper foil that have completed the first etching through prepreg to form a multilayer board. Apply photosensitive films to both non-lamination surfaces of the multilayer board, and perform the second pattern transfer.

[0009] Perform the second etching at the first etching positions on both non-lamination surfaces of the multilayer board to expose the prepreg in the multilayer board.

[0010] Wherein, the sum of the first preset etching depth and the second preset etching depth is less than the copper foil thickness.

[0011] By first performing double-sided first etching and then non-laminated surface second etching, the ultra-thick copper foil is etched three times respectively, significantly improving the problems of severe side etching and poor etching factor in the traditional process for ultra-thick copper circuit boards. After dividing the ultra-thick copper into three etching depths, since the single etching depth is reduced, the side etching is less, thus ensuring the stability of the line width and being able to meet the production requirements for smaller line pitches at the same time. On the other hand, since the adjacent two layers of copper foil are laminated with the prepreg immediately after the first etching on the laminated surface, compared with the one-time lamination in the traditional process, the filling depth and filling pressure of the prepreg are significantly reduced, enabling the prepreg to completely fill the line pitch and avoiding the occurrence of lamination voids, thereby improving the reliability of the ultra-thick copper circuit board.

[0012] In a preferred technical solution of the present invention, a photosensitive film is attached to both the laminated surface and the non-laminated surface of the copper foil, and the first pattern transfer is performed, including:

[0013] A photosensitive film is attached to both the laminated surface and the non-laminated surface of the copper foil;

[0014] When performing the first pattern transfer on the copper foil, the non-laminated surface of the copper foil uses the front image of the predetermined circuit pattern, and the laminated surface of the copper foil uses the mirror image of the predetermined circuit pattern;

[0015] After completing the first pattern transfer, a developer is used to remove the unexposed photosensitive film covered on the copper foil, exposing the positions of the copper foil to be etched.

[0016] The non-laminated surface of the copper foil uses the front image of the predetermined circuit pattern, while the laminated surface uses the mirror image of the predetermined circuit pattern, ensuring that in the subsequent lamination process, the circuit patterns on both sides of the copper foil can be accurately aligned, so that a complete layer of circuit can be finally obtained; after completing the first pattern transfer, a developer is used to remove the unexposed photosensitive film on the copper foil, thereby exposing the positions of the copper foil to be etched, preparing for the subsequent etching process.

[0017] In a preferred technical solution of the present invention, when performing the first pattern transfer on the copper foil, the predetermined circuit pattern is subjected to line compensation. When performing line compensation on the predetermined circuit pattern, it includes:

[0018] Performing line compensation on the front image of the predetermined circuit pattern according to the compensation rule corresponding to the second preset etching depth, and performing line compensation on the mirror image of the predetermined circuit pattern according to the compensation rule corresponding to the first preset etching depth;

[0019] When the value of the first preset etching depth and / or the value of the second preset depth is a non-integer, it is rounded up to the closest integer value as the depth specification corresponding to the compensation rule.

[0020] Adjusting the front image and mirror image of a predetermined circuit diagram according to a preset etching depth can ensure the accuracy of the circuit pattern on the PCB board. Since the circuit compensation is related to the etching depth, and there may be differences in the etching depths of the pressed surface and the non-pressed surface, the compensation rules for the front image and the mirror image are different and need to be designed specifically to ensure the accuracy of the final presented circuit.

[0021] In a preferred technical solution of the present invention, the first preset etching depth is greater than or equal to the second preset etching depth.

[0022] Since the pressed surface is etched only once in one direction, while the non-pressed surface needs to be etched twice in one direction, the best etching depth for the pressed surface is set to 1 / 3 of the copper foil thickness. The best etching depth for the first etching of the non-pressed surface is set to be equal to or less than 1 / 3. When the non-pressed surface is etched for the second time, the etching depth is the difference between 2 / 3 of the copper foil thickness and the first etching depth of the non-pressed surface. In this way, the three etching depths are all approximately 1 / 3 of the copper foil thickness, and the etching factor is optimized to the best value.

[0023] In a preferred technical solution of the present invention, when performing the second graphic transfer on a multilayer board, the predetermined circuit diagram used has been compensated for the circuit. When compensating the predetermined circuit diagram, it includes:

[0024] Compensating the predetermined circuit diagram according to the compensation rule corresponding to the difference between the copper foil thickness and the first preset etching depth;

[0025] When the difference between the copper foil thickness and the first preset etching depth is a non-integer, it is rounded up to the nearest integer value as the depth specification corresponding to the compensation rule.

[0026] The compensation rule of the circuit is related to the etching depth. Since two slopes in a V shape are formed on the copper foil during the first etching of the non-pressed surface of the multilayer board, when etching the non-pressed surface for the second time, the two slopes need to be etched away first and then continue to etch downwards. Therefore, the depth specification corresponding to the compensation rule used for the predetermined circuit diagram in the second graphic transfer should be the difference between the copper foil thickness and the first preset etching depth.

[0027] In a preferred technical solution of the present invention, for the predetermined circuit diagram used in the first graphic transfer, the preset line width in the mirror image is the final design width, and the preset line width in the front image is less than the final design width;

[0028] The preset line width of the predetermined circuit diagram used in the second graphic transfer is the final design width.

[0029] The circuit in the copper foil is formed by etching in two directions, up and down, while the pressing surface is only etched once. It is required that the final designed circuit width can be obtained in one etching step. Therefore, the preset circuit width of the preset circuit diagram adopted is the final designed width, rather than the pressing surface being etched twice at the same position. The side etching caused by the second etching will widen the circuit spacing formed during the first etching. Therefore, the preset circuit width during the first etching needs to be less than the final designed width, and the final designed width is adopted during the second etching. While ensuring that the bottom of the etching position during the second etching can completely expose the bottom of the first etching position on the pressing surface, it also ensures that the circuit width exactly reaches the final designed width after the second etching.

[0030] In a preferred technical solution of the present invention, both the first etching and the second etching are acid etching. Among them, after the first acid etching is completed, a chemical stripping solution is used to remove the photosensitive film on the pressing surface and the non-pressing surface of the copper foil. After the second acid etching is completed, a chemical stripping solution is used to remove the photosensitive film on the non-pressing surface of the multilayer board.

[0031] Using a chemical stripping solution to remove the photosensitive film after each acid etching can effectively avoid short-circuit problems caused by photosensitive film residue and improve etching accuracy and reliability.

[0032] In a preferred technical solution of the present invention, before pressing the adjacent two layers of copper foil that have completed the first etching through a prepreg to form a multilayer board, the method further includes: determining the thickness of the prepreg by calculating the total resin amount and filling measure of the prepreg, and then closely attaching the pressing surfaces of the adjacent two layers of copper foil to the two opposite surfaces of the prepreg with the determined thickness for pre-laminating.

[0033] Determining the thickness of the prepreg by calculating the total resin amount and filling measure of the prepreg, and closely attaching the pressing surfaces of the adjacent two layers of copper foil to the corresponding thickness of the prepreg before formal pressing to ensure that the prepreg can fully fill the circuit gap during the pressing process and avoid problems such as voids or insufficient filling.

[0034] In a preferred technical solution of the present invention, the method further includes: processing at least one multilayer board that has completed the second etching and removed the photosensitive film into a finished ultra-thick copper circuit board. When the finished ultra-thick copper circuit board includes a single multilayer board, the single multilayer board is processed into a finished ultra-thick copper circuit board through a post-treatment step;

[0035] When the finished ultra-thick copper circuit board includes multiple multilayer boards, after pressing the multiple multilayer boards through a prepreg, they are further processed into a finished ultra-thick copper circuit board through a post-treatment step.

[0036] According to the requirements of the finished ultra-thick copper circuit board, a single multilayer board or multiple multilayer boards can be flexibly selected for processing to adapt to different application scenarios and customer requirements. Through post-treatment steps such as outer layer etching, printing green oil, and surface treatment, the multilayer board is further optimized and quality controlled to ensure the reliability of the finished ultra-thick copper circuit board.

[0037] The second object of the present invention is to provide an ultra-thick copper PCB, which is made by using the above-mentioned method for manufacturing an ultra-thick copper PCB.

[0038] The beneficial effects of the present invention are as follows:

[0039] The method for manufacturing an ultra-thick copper PCB provided by the present invention enables the ultra-thick copper foil to be etched three times by first performing double-sided first etching and then second etching on the non-laminated surface. This significantly improves the problems of severe side etching and poor etching factor in the traditional process of ultra-thick copper circuit boards. After dividing the ultra-thick copper into three etching depths, since the single-etching depth is reduced, the side etching is less, thus ensuring the stability of the line width and being able to meet the production requirements of smaller line spacings at the same time. When laminating the adjacent two copper foils that have completed the first etching on the laminated surface with the prepreg, compared with the one-time lamination of the whole copper foil and the prepreg in the traditional process, the filling depth and filling pressure of the prepreg are greatly reduced, enabling the prepreg to completely fill the line spacing and avoiding the occurrence of lamination voids, thereby improving the reliability of the ultra-thick copper circuit board.

[0040] The ultra-thick copper PCB provided by the present invention uses the method of first performing double-sided first etching and then second etching on the non-laminated surface when manufacturing, which reduces the side etching generated during the copper foil etching process. It can produce ultra-thick copper circuit boards with a thickness of more than 8 oz and can also meet the production requirements of smaller line spacings at the same time. According to the requirements of the finished ultra-thick copper circuit board, a single multilayer board or multiple multilayer boards can be flexibly selected for processing to adapt to different application scenarios and customer requirements. Description of the Drawings

[0041] Figure 1 is a schematic diagram of the manufacturing process of a method for manufacturing an ultra-thick copper PCB in an embodiment of the present invention.

[0042] Reference Signs:

[0043] 10. Copper Foil; 11. Positioning Hole; 21. First Etching Position on the Non-Laminated Surface; 22. First Etching Position on the Laminated Surface; 23. Second Etching Position on the Non-Laminated Surface; 30. Aluminum Sheet; 40. Prepreg; 41. T-Tape; 50. Photosensitive Film; 60. Outer Layer. Detailed Embodiments

[0044] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0045] Ultra-thick copper circuit boards generally refer to circuit boards with a copper foil thickness of more than 6 oz. Due to their high current-carrying capacity and excellent heat dissipation performance, ultra-thick copper circuit boards are widely used in high-current and high-voltage electronic devices such as power amplifiers, charging devices, inverters, vehicle lights, and automotive high-voltage modules.

[0046] However, there are many difficult-to-overcome problems in the traditional manufacturing methods of ultra-thick copper circuit boards, especially for circuit boards with an inner copper thickness of more than 8 oz: First, when etching the circuit board, side etching is likely to occur. The thicker the copper layer, the more serious the side etching and the worse the etching factor, which will cause the line width of the ultra-thick copper circuit board to become narrower and the line spacing to become larger, affecting the accuracy of the circuit. Second, when using the special structure of the glass cloth in the prepreg lamination to fill the ultra-thick copper line spacing at one time, due to the insufficient resin flow layer on one side of this type of prepreg, it is difficult to completely fill the line spacing, and voids are likely to occur during lamination, thus affecting the reliability of the circuit board.

[0047] Based on this, the present application provides an ultra-thick copper PCB and its manufacturing method.

[0048] Example 1

[0049] See Figure 1 , an ultra-thick copper PCB manufacturing method provided in this embodiment includes the following steps:

[0050] As shown in step 100, prepare copper foil 10. Step 110 is to perform pretreatment on copper foil 10, where the pretreatment includes processes such as drilling positioning holes 11 and improving the surface adhesion of copper foil 10;

[0051] Attach photosensitive films 50 to both the lamination surface and the non-lamination surface of copper foil 10;

[0052] Perform the first graphic transfer on both the lamination surface and the non-lamination surface of copper foil 10 simultaneously. During the first graphic transfer, the non-lamination surface of copper foil 10 uses the positive image of the predetermined circuit diagram, and the lamination surface of copper foil 10 uses the mirror image of the predetermined circuit diagram;

[0053] After completing the first graphic transfer, use a developer to remove the unexposed photosensitive film 50 covered on copper foil 10, exposing the position of copper foil 10 to be etched;

[0054] As shown in step 120, the bonding surface and the non-bonding surface of the copper foil 10 are subjected to the first acidic etching, wherein the bonding surface is etched to a first preset etching depth, the non-bonding surface is etched to a second preset etching depth, the first preset etching depth is greater than or equal to the second preset etching depth, and the sum of the first preset etching depth and the second preset etching depth is less than the thickness of the copper foil 10; after the first acidic etching of the bonding surface, a T-shaped platform 41 is formed on the bottom surface of the etched position.

[0055] After completing the first acidic etching, a chemical stripping solution is used to remove the photosensitive film 50 from the bonding surface and the non-bonding surface of the copper foil 10.

[0056] Calculate the total resin amount and filling measure of the prepreg 40, determine the thickness of the prepreg 40, and then pre-stack the bonding surfaces of two adjacent copper foils 10 close to the two opposite surfaces of the prepreg 40 with the determined thickness. As shown in step 200, usually an aluminum sheet 30 is added to the surface of the copper foil 10 to assist subsequent lamination.

[0057] In step 300, two adjacent copper foils 10 are laminated through the prepreg 40 to form a multilayer board; wherein, after the lamination is completed, the prepreg 40 completely fills the T-shaped platform 41 on the bottom surface of the first acidic etching position, as Figure 1 the raised platform position of the shaded part shown in step 300.

[0058] As shown in step 400, photosensitive films 50 are attached to the two non-bonding surfaces of the multilayer board again.

[0059] Perform a second pattern transfer on the two non-bonding surfaces of the multilayer board, wherein the second pattern transfer uses the positive image of a predetermined circuit diagram.

[0060] After completing the second pattern transfer, as Figure 1 shown, in step 410, a developing solution is used again to remove the unexposed photosensitive film 50 covering the non-bonding surface of the multilayer board, exposing the position of the copper foil 10 to be etched.

[0061] As shown in step 500, a second acidic etching is performed on the first acidic etching positions of the two non-bonding surfaces of the multilayer board until the T-shaped platform 41 filled with the prepreg 40 is completely exposed, and after the second acidic etching is completed, the bottom surface width of the etched position on the non-bonding surface is the same as the bottom surface width of the first acidic etching position on the bonding surface.

[0062] After completing the second acidic etching, in step 510, a chemical stripping solution is used to remove the photosensitive film 50 from the non-bonding surface of the multilayer board.

[0063] As shown in step 600, post-treatment is performed on the multilayer board, wherein the post-treatment includes steps such as outer layer 60 etching, printing solder mask, surface treatment, etc., and a finished ultra-thick copper circuit board is obtained in step 610.

[0064] In practical applications, when performing the first graphic transfer on the copper foil 10, the predetermined circuit diagram is subjected to circuit compensation. When performing circuit compensation on the predetermined circuit diagram, the front image of the predetermined circuit diagram is compensated according to the compensation rule corresponding to the second preset etching depth, and the mirror image of the predetermined circuit diagram is compensated according to the compensation rule corresponding to the first preset etching depth;

[0065] When the value of the first preset etching depth and / or the second preset depth is a non-integer, it is rounded up to the nearest integer value as the depth specification corresponding to the compensation rule;

[0066] Adjusting the front image and the mirror image of the predetermined circuit diagram according to the preset etching depth can ensure that the circuit pattern on the PCB board is accurate. Since the circuit compensation is related to the etching depth, and there may be differences in the etching depths of the pressed surface and the non-pressed surface, the compensation rules for the front image and the mirror image are different and need to be designed specifically to ensure the accuracy of the final presented circuit;

[0067] When performing the second graphic transfer on the multilayer board, the predetermined circuit diagram used is subjected to circuit compensation. When performing circuit compensation on the predetermined circuit diagram, the predetermined circuit diagram is compensated according to the compensation rule corresponding to the difference between the thickness of the copper foil 10 and the first preset etching depth;

[0068] When the difference between the thickness of the copper foil 10 and the first preset etching depth is a non-integer, it is rounded up to the nearest integer value as the depth specification corresponding to the compensation rule;

[0069] The compensation rule of the circuit is related to the etching depth. Since two slopes in a V shape are formed on the copper foil 10 during the first etching of the non-pressed surface of the multilayer board, when etching the non-pressed surface for the second time, the two slopes need to be etched away first and then continue to etch downwards. Therefore, the depth specification corresponding to the compensation rule used for the predetermined circuit diagram during the second graphic transfer should be the difference between the thickness of the copper foil 10 and the first preset etching depth.

[0070] For the predetermined circuit diagram used during the first graphic transfer, the preset circuit width in the mirror image is the final design width, and the preset circuit width in the front image is less than the final design width; the preset circuit width of the predetermined circuit diagram used during the second graphic transfer is the final design width;

[0071] The circuits in the copper foil 10 are formed by etching in both the upper and lower directions. For the lamination surface, only one etching is performed, and the desired circuit width of the final design can be obtained in one etching operation. Therefore, the preset circuit width of the preset circuit diagram adopted is the final design width. Instead of performing two etchings on the lamination surface at the same position, the side etching caused by the second etching will widen the circuit pitch formed during the first etching. Therefore, the preset circuit width during the first etching needs to be less than the final design width, and the final design width is used during the second etching. While ensuring that the bottom of the etching position during the second etching can completely expose the bottom of the first etching position 22 on the lamination surface, it also ensures that the circuit width exactly reaches the final design width after the second etching.

[0072] In the present invention, by first performing a first double-sided etching and then a second etching on the non-lamination surface, the ultra-thick copper foil 10 is etched three times respectively, significantly improving the problems of severe side etching and poor etching factor in the traditional process for ultra-thick copper circuit boards. After dividing the ultra-thick copper into three etching depths, since the single-etching depth is reduced, the side etching is less, thus ensuring the stability of the circuit width and being able to meet the production requirements for smaller circuit pitches at the same time. The adjacent two layers of copper foil 10 and prepreg 40 that have completed the first etching on the lamination surface are laminated, which significantly reduces the filling depth and filling pressure of the prepreg 40 compared to the one-time lamination of the entire copper foil 10 and prepreg 40 in the traditional process, enabling the prepreg 40 to completely fill the circuit pitch and avoiding the occurrence of lamination voids, thereby improving the reliability of the ultra-thick copper circuit board.

[0073] Example 2

[0074] See Figure 1 , a method for manufacturing an ultra-thick copper PCB provided in this embodiment includes the following steps:

[0075] Prepare a copper foil 10 with a thickness of 8 oz, and perform pre-treatment on the copper foil 10. The pre-treatment includes processes such as drilling positioning holes 11 and improving the surface adhesion of the copper foil 10.

[0076] Apply a photosensitive film 50 to both the lamination surface and the non-lamination surface of the copper foil 10.

[0077] Perform the first pattern transfer on both the lamination surface and the non-lamination surface of the copper foil 10 simultaneously. During the first pattern transfer, the non-lamination surface of the copper foil 10 uses the positive image of the preset circuit diagram, and the lamination surface of the copper foil 10 uses the mirror image of the preset circuit diagram. Moreover, both the lamination surface and the non-lamination surface use an exposure parameter with a PE value of 20 μm and automatic alignment. During exposure, a photochemical chain reaction is carried out on the patterns to be retained, and the positions that are not needed are not sensitized.

[0078] After the first graphic transfer is completed, a potassium carbonate solution is used to remove the unexposed photosensitive film 50 covering the copper foil 10, exposing the position of the copper foil 10 to be etched;

[0079] Perform the first acidic etching on the bonding surface and non-bonding surface of the copper foil 10. Among them, when the target circuit board is a large-gap circuit, the bonding surface is etched to a depth of 1 / 3 of the thickness of the copper foil 10. When the target circuit board is a small-gap circuit, the etching depth of the bonding surface is slightly less than 1 / 3 of the thickness of the copper foil 10. The etching depth of the non-bonding surface is slightly less than the etching depth of the bonding surface, but also close to 1 / 3 of the thickness of the copper foil 10, leaving a reserved thickness close to 1 / 3 of the thickness of the copper foil 10 to ensure that there is sufficient rigidity to support the copper foil 10 without deformation or fracture during subsequent lamination; when performing acidic etching, a depth gauge is used to measure the etching depth value; after the first acidic etching of the bonding surface, a T-shaped platform 41 is formed on the bottom surface of the etched position, as Figure 1 shown;

[0080] After the first acidic etching is completed, a sodium hydroxide solution is used to remove the photosensitive film 50 on the bonding surface and non-bonding surface of the copper foil 10;

[0081] Calculate the total resin amount and filling measure of the prepreg 40, and determine the thickness of the prepreg 40. In this implementation, the thickness of the cream layer ≥ 5um. Then, the bonding surfaces of two adjacent copper foils 10 are respectively brought close to the two opposite surfaces of the prepreg 40 of this thickness for pre-lamination. Usually, aluminum sheets 30 are added to the surface of the copper foil 10 to assist subsequent lamination;

[0082] Bond two adjacent copper foils 10 through high-temperature and high-pressure heat fusion and curing using the prepreg 40 to form a multilayer board; among them, after the lamination is completed, the prepreg 40 completely fills the T-shaped platform 41 on the bottom surface of the first acidic etching position;

[0083] Attach the photosensitive film 50 to the two non-bonding surfaces of the multilayer board again;

[0084] Perform the second graphic transfer on the two non-bonding surfaces of the multilayer board. Among them, the second graphic transfer uses the front image of the predetermined circuit diagram and the exposure parameter with a PE value of 20μm, and uses the previously drilled positioning holes 11 for alignment;

[0085] After the second graphic transfer is completed, use the potassium carbonate solution again to remove the unexposed photosensitive film 50 covering the non-bonding surface of the multilayer board, exposing the position of the copper foil 10 to be etched;

[0086] Perform the second acidic etching on the first acidic etching positions of the two non-bonding surfaces of the multilayer board until the T-shaped platform 41 filled with the prepreg 40 is completely exposed. After the second acidic etching is completed, the bottom surface width of the etched position on the non-bonding surface is the same as the bottom surface width of the first acidic etching position on the bonding surface;

[0087] After the second acidic etching is completed, a sodium hydroxide solution is used to remove the photosensitive film 50 from the non-pressed surface of the multilayer board;

[0088] The multilayer board is post-processed, and the post-processing includes steps such as outer layer 60 etching, green oil printing, surface treatment, etc., to obtain a finished ultra-thick copper circuit board.

[0089] In practical applications, when performing the first graphic transfer on the copper foil 10, the predetermined circuit diagram is subjected to circuit compensation. When performing circuit compensation on the predetermined circuit diagram, the front image of the predetermined circuit diagram is compensated according to the compensation rule corresponding to the second preset etching depth, and the mirror image of the predetermined circuit diagram is compensated according to the compensation rule corresponding to the first preset etching depth;

[0090] When the value of the first preset etching depth and / or the second preset depth value is a non-integer, it is rounded up to the nearest integer value as the depth specification corresponding to the compensation rule;

[0091] In this embodiment, when performing circuit compensation on the pattern of the pressed surface, the compensation rule corresponding to 3 oz is used for compensation, that is, the circuit width is increased by 4 mil, the circuit spacing is reduced by 4 mil, and the circuit spacing of the non-pressed surface is reduced by 24 mil. When the circuit spacing is not sufficient to be reduced by 24 mil, the circuit spacing is reduced to the limit circuit spacing of 3.9 mil to ensure that there is enough position of the copper foil 10 when pasting the photosensitive film 50 for the second time.

[0092] Adjusting the front image and the mirror image of the predetermined circuit diagram according to the preset etching depth can ensure that the circuit pattern on the PCB board is accurate. Since the circuit compensation is related to the etching depth, and there may be differences in the etching depths of the pressed surface and the non-pressed surface, the compensation rules for the front image and the mirror image are different and need to be designed specifically to ensure the accuracy of the final presented circuit;

[0093] When performing the second graphic transfer on the multilayer board, the predetermined circuit diagram used is subjected to circuit compensation. When performing circuit compensation on the predetermined circuit diagram, the predetermined circuit diagram is compensated according to the compensation rule corresponding to the difference between the thickness of the copper foil 10 and the first preset etching depth;

[0094] When the difference between the thickness of the copper foil 10 and the first preset etching depth is a non-integer, it is rounded up to the nearest integer value as the depth specification corresponding to the compensation rule;

[0095] In this embodiment, when performing circuit compensation on the predetermined circuit diagram used in the second graphic transfer, the compensation rule corresponding to 6 oz is used for compensation, that is, the circuit width is increased by 8 mil and the circuit spacing is reduced by 8 mil.

[0096] The compensation rule of the circuit is related to the etching depth. Since two V-shaped slopes are formed on the copper foil 10 during the first etching of the non-pressed surface of the multi-layer board, when the non-pressed surface is etched for the second time, the two slopes need to be etched away first and then continue to etch downwards. Therefore, the depth specification corresponding to the compensation rule used in the predetermined circuit diagram adopted during the second pattern transfer should be the difference between the thickness of the copper foil 10 and the first preset etching depth.

[0097] For the predetermined circuit diagram adopted during the first pattern transfer, the preset line width in the mirror image is the final design width, and the preset line width in the front image is less than the final design width; the preset line width of the predetermined circuit diagram adopted during the second pattern transfer is the final design width;

[0098] The circuit in the copper foil 10 is formed by etching in two directions, up and down. And the pressed surface is only etched once, and the final designed line width can be obtained by one etching. Therefore, the preset line width of the adopted predetermined circuit diagram is the final design width. While the non-pressed surface is etched twice at the same position, the side etching generated during the second etching will widen the line spacing formed during the first etching. Therefore, the preset line width during the first etching needs to be less than the final design width, and the final design width is adopted during the second etching. While ensuring that the bottom of the etching position during the second etching can completely expose the bottom of the first etching position 22 of the pressed surface, it also ensures that the line width has reached the final design width after the second etching.

[0099] In the present invention, by first performing double-sided first etching and then performing second etching on the non-pressed surface, the ultra-thick copper foil 10 is etched three times respectively, significantly improving the problems of serious side etching and poor etching factor in the traditional process for ultra-thick copper circuit boards. After dividing the ultra-thick copper into three etching depths, since the single etching depth is reduced, the side etching is less, so the stability of the line width is ensured, and at the same time, the production requirements for smaller line spacing can be met; Pressing the adjacent two layers of copper foil 10 and the semi-cured sheet 40 that have completed the first etching on the pressed surface, compared with the one-time pressing of the whole copper foil 10 and the semi-cured sheet 40 in the traditional process, the filling depth and filling pressure of the semi-cured sheet 40 are greatly reduced, enabling the semi-cured sheet 40 to completely fill the line spacing and avoiding the occurrence of pressing voids, thereby improving the reliability of the ultra-thick copper circuit board.

[0100] Embodiment 3

[0101] See Figure 1 , a method for manufacturing an ultra-thick copper PCB provided in this embodiment includes the following steps:

[0102] Different from Embodiment 2, in this embodiment, after completing the second acidic etching and removing the photosensitive film 50 on the non-pressed surface of the multi-layer board using a chemical stripping solution;

[0103] According to requirements, multiple multilayer boards are pre-laminated and then laminated through the prepreg 40.

[0104] The multilayer boards after lamination are post-processed, where the post-processing includes steps such as outer layer 60 etching, outer layer 60 lamination, printing solder mask, surface treatment, etc. After the post-processing is completed, a finished ultra-thick copper circuit board is obtained.

[0105] According to the requirements of the finished ultra-thick copper circuit board, a single multilayer board or multiple multilayer boards can be flexibly selected for processing to adapt to different application scenarios and customer requirements. Through post-processing steps such as outer layer 60 etching, printing solder mask, surface treatment, etc., the multilayer boards are further optimized and quality controlled to ensure the reliability of the finished ultra-thick copper circuit board.

[0106] Embodiment 4

[0107] See Figure 1 , this embodiment provides an ultra-thick copper PCB. This circuit board adopts the above-mentioned manufacturing method of ultra-thick copper PCB. During manufacturing, the method of first performing double-sided first etching and then non-laminated surface second etching is used, so that the side etching generated when the copper foil 10 etches the circuit is reduced. While being able to produce ultra-thick copper circuit boards with a thickness of more than 8 oz, it can also meet the production requirements of smaller line spacings.

[0108] According to the requirements of the finished ultra-thick copper circuit board, a single multilayer board or multiple multilayer boards can be flexibly selected for processing to adapt to different application scenarios and customer requirements.

[0109] For the sake of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "upper" etc. can be used here to describe the spatial positional relationship between a device or feature shown in the figure and other devices or features. It should be understood that the spatial relative terms are intended to include different orientations during use or operation in addition to the orientation of the device described in the figure. For example, if the device in the figure is inverted, the device described as "above other devices or structures" or "over other devices or structures" will be positioned as "below other devices or structures" or "under other devices or structures" afterwards. Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the corresponding explanations are made for the spatial relative descriptions used here.

[0110] In addition, it should be noted that using words such as "first", "second", etc. to limit components is only for the convenience of differentiating the corresponding components. Without additional declaration, the above words have no special meaning, so they cannot be understood as a limitation on the protection scope of this application.

[0111] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A manufacturing method for ultra-thick copper PCB, characterized in that: It includes the following steps: Apply photosensitive films to both the bonding surface and the non-bonding surface of the copper foil, and perform the first pattern transfer; Perform the first etching on both the bonding surface and the non-bonding surface of the copper foil. Among them, the bonding surface is etched to the first preset etching depth, and the non-bonding surface is etched to the second preset etching depth; Press the adjacent two layers of copper foil that have completed the first etching through prepregs to form a multilayer board. Apply photosensitive films to both non-bonding surfaces of the multilayer board, and perform the second pattern transfer; Perform the second etching at the positions of the first etching on both non-bonding surfaces of the multilayer board to expose the prepregs in the multilayer board; Among them, the sum of the first preset etching depth and the second preset etching depth is less than the thickness of the copper foil.

2. A method for manufacturing an ultra-thick copper PCB according to claim 1, wherein: Applying photosensitive films to both the bonding surface and the non-bonding surface of the copper foil and performing the first pattern transfer includes: Apply photosensitive films to both the bonding surface and the non-bonding surface of the copper foil; When performing the first pattern transfer on the copper foil, for the non-bonding surface of the copper foil, use the positive image of the predetermined circuit pattern, and for the bonding surface of the copper foil, use the mirror image of the predetermined circuit pattern; After completing the first pattern transfer, use a developer to remove the unexposed photosensitive film covered on the copper foil, exposing the positions of the copper foil to be etched.

3. A method for manufacturing an ultra-thick copper PCB according to claim 2, wherein: When performing the first pattern transfer on the copper foil, the predetermined circuit pattern is subjected to circuit compensation. When performing circuit compensation on the predetermined circuit pattern, it includes: Perform circuit compensation on the positive image of the predetermined circuit pattern according to the compensation rule corresponding to the second preset etching depth, and perform circuit compensation on the mirror image of the predetermined circuit pattern according to the compensation rule corresponding to the first preset etching depth; When the value of the first preset etching depth and / or the value of the second preset depth is a non-integer, round up to the nearest integer value as the depth specification corresponding to the compensation rule.

4. A method for manufacturing an ultra-thick copper PCB according to claim 1, wherein: The first preset etching depth is greater than or equal to the second preset etching depth.

5. A method for manufacturing an ultra-thick copper PCB according to claim 1, wherein: When performing the second pattern transfer on the multilayer board, the predetermined circuit pattern used is subjected to circuit compensation. When performing circuit compensation on the predetermined circuit pattern, it includes: Perform circuit compensation on the predetermined circuit pattern according to the compensation rule corresponding to the difference between the copper foil thickness and the first preset etching depth; When the difference between the copper foil thickness and the first preset etching depth is a non-integer, round up to the nearest integer value as the depth specification corresponding to the compensation rule.

6. A method for manufacturing an ultra-thick copper PCB according to claim 2, wherein: For the predetermined circuit pattern used in the first pattern transfer, the preset line width in the mirror image is the final design width, and the preset line width in the positive image is less than the final design width; The preset line width of the predetermined circuit pattern used in the second pattern transfer is the final design width.

7. A method for manufacturing an ultra-thick copper PCB according to claim 1, wherein: Both the first etching and the second etching are acid etching. After the first acid etching is completed, a chemical stripping solution is used to remove the photosensitive film from the pressed surface and the non-pressed surface of the copper foil. After the second acid etching is completed, a chemical stripping solution is used to remove the photosensitive film from the non-pressed surface of the multilayer board.

8. A method for manufacturing a super-thick copper PCB according to claim 1, wherein: Before the adjacent two layers of copper foil after the first etching are laminated to form a multilayer board through a prepreg, the method further includes: determining the thickness of the prepreg by calculating the total resin amount and the filling measure of the prepreg, and then pre-laminating the pressed surfaces of the adjacent two layers of copper foil against the two opposite surfaces of the prepreg with the determined thickness.

9. A method for manufacturing a super-thick copper PCB according to claim 7, wherein: The method further includes: processing at least one multilayer board after the second etching and the removal of the photosensitive film into a finished super-thick copper circuit board. When the finished super-thick copper circuit board includes a single multilayer board, the single multilayer board is processed into a finished super-thick copper circuit board through a post-treatment step; When the finished super-thick copper circuit board includes multiple multilayer boards, the multiple multilayer boards are laminated through a prepreg and then processed into a finished super-thick copper circuit board through a post-treatment step.

10. A super-thick copper PCB, characterized in that: It is made by using the method for manufacturing a super-thick copper PCB according to any one of claims 1-9.

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