Millimeter wave radar circuit board processing method and millimeter wave radar circuit board

Abstract

The invention discloses a processing method of a millimeter wave radar circuit board, which adopts a continuous blind slot to replace a plurality of independent blind hole structures in a traditional structure, so that a continuous radio frequency circuit pattern can be formed, the signal shielding area is effectively increased, and the millimeter wave radar circuit board has a better signal shielding effect. Besides, the processing method of the embodiment of the invention also cancels the procedures of repeated electroplating, single-side copper reduction, circuit etching and the like in the traditional processing method, and can directly realize the manufacturing of the outer circuit, the first copper layer and the second copper layer through activation and copper deposition, thereby greatly shortening the processing flow of the millimeter wave radar circuit board, and improving the production efficiency of the millimeter wave radar circuit board. And the production efficiency of the millimeter wave radar circuit board is improved. In addition, the invention further discloses the millimeter-wave radar circuit board formed by the processing method of the millimeter-wave radar circuit board.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board processing, and in particular to a processing method of a millimeter wave radar circuit board and a millimeter wave radar circuit board. Background Art

[0002] At present, the main way to shield the signal of the millimeter-wave radar circuit board is to add blind holes in the RF circuit layer, and then fill the blind holes by electroplating, and achieve signal shielding through the copper layer. The specific process is: inner layer circuit production → pressing plate → browning → laser blind hole → de-browning → mechanical drilling → high-pressure water washing → glue removal → hole metallization → hole filling electroplating → pulse electroplating → copper reduction film → single-sided copper reduction → line etching. The millimeter-wave radar circuit board formed by this processing method cannot achieve full closure of the signal due to the spacing between adjacent blind holes, and is prone to signal leakage. In addition, in this processing method, because there are blind holes and through holes in the circuit board at the same time, it is usually impossible to achieve through-blind co-plating at one time due to the influence of the hole filling electroplating capacity. It is necessary to undergo hole filling electroplating and pulse electroplating. After electroplating, it is necessary to reduce copper on one side and etch the line to realize the production of the RF antenna layer. The processing process is long and the production efficiency is low. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for processing a millimeter wave radar circuit board, which can not only improve the signal shielding effect, but also shorten the processing flow and improve the production efficiency of the millimeter wave radar circuit board.

[0004] The present invention also provides a millimeter wave radar circuit board formed by the above-mentioned millimeter wave radar circuit board processing method.

[0005] The method for processing a millimeter wave radar circuit board according to an embodiment of the present invention comprises the following steps:

[0006] S1: Obtain at least two copper substrates, and fabricate inner-layer circuits on the copper substrates;

[0007] S2: Pressing the plate, alternately stacking all the copper substrates and the prepreg layers to form an inner core board assembly, setting an upper insulating layer on the upper surface of the inner core board assembly, setting a lower insulating layer on the lower surface of the inner core board assembly, and pressing the upper insulating layer, the inner core board assembly and the lower insulating layer to form a multilayer board;

[0008] S3: mechanical drilling to form through holes penetrating the multilayer board;

[0009] S4: laser blind grooves, where one of the copper substrates is a shielding layer, and a blind groove extending downward to the shielding layer is processed on the upper surface of the upper insulating layer by CO2 ablation, and the blind grooves are continuously arranged to form a radio frequency circuit pattern;

[0010] S5: removing glue, removing the residual glue at the bottom of the blind groove;

[0011] S6: Activation, depositing a layer of activation factor on the upper surface of the upper insulating layer, the lower surface of the lower insulating layer, the wall of the through hole and the inner wall of the blind groove to form an activation layer;

[0012] S7: exposing and developing, attaching a dry film to the upper surface of the upper insulating layer and the lower surface of the lower insulating layer, and exposing and developing to reveal the outer circuit area, the blind groove and the through hole;

[0013] S8: copper deposition, forming an outer layer circuit in the outer layer circuit area, forming a first copper layer on the inner wall of the blind groove, and forming a second copper layer on the inner wall of the through hole;

[0014] S9: film stripping, removing the dry film on the surface of the inner core board assembly;

[0015] S10: Post-process.

[0016] The method for processing a millimeter wave radar circuit board according to an embodiment of the present invention has at least the following beneficial effects:

[0017] By adopting the processing method of the millimeter-wave radar circuit board of the embodiment of the present invention, a continuous blind groove is used to replace the multiple independent blind hole structures in the traditional structure, thereby forming a continuous RF circuit pattern, effectively increasing the signal shielding area, so that the millimeter-wave radar circuit board has a better signal shielding effect. In addition, the processing method of the embodiment of the present invention also eliminates the processes of multiple electroplating, single-sided copper reduction, and circuit etching in the traditional processing method, and can directly realize the production of the outer layer circuit, the first copper layer, and the second copper layer through activation and copper deposition, which greatly shortens the processing flow of the millimeter-wave radar circuit board and improves the production efficiency of the millimeter-wave radar circuit board.

[0018] According to some embodiments of the present invention, step S2 also includes: attaching a resistive film on the upper surface of the upper insulating layer and the lower surface of the lower insulating layer, pressing the stacked resistive film, upper insulating layer, inner core board assembly, and lower insulating layer, and removing the two resistive films after pressing.

[0019] According to some embodiments of the present invention, in step S2, the pressing process is divided into 10 sections, and at least one parameter of the temperature, time and pressure of two adjacent pressing processes is adjusted; vacuuming is performed in sections 1 to 8, the vacuum setting value is <30mbar, and the total pressing time of sections 1 to 10 is 180min-220min; vacuuming is stopped in section 9 and the vacuum is released in section 10, the pressing time of section 9 is 45min, and the pressing time of section 10 is 20min.

[0020] According to some embodiments of the present invention, the thickness of the shielding layer is C, C≥25μm, the ablation depth of the blind groove on the shielding layer in step S4 is c, c≤3μm, the top width of the blind groove is a, the bottom width is b, 0.8≤a / b≤1.

[0021] According to some embodiments of the present invention, the blind groove is processed by stacked hole ablation, and the CO2 ablation process is divided into 7 shots, the pulse energy of each shot is 28mj, the beam diameter is 3mm, wherein the pulse width of the first shot is 18μs, the pulse width of the second to fourth shots is 10μs, and the pulse width of the fifth to seventh shots is 8μs.

[0022] According to some embodiments of the present invention, step S5 comprises:

[0023] S5.1: grinding the plate to remove burrs at the through hole and the blind groove, and grinding the upper surface of the upper insulating layer and the lower surface of the lower insulating layer;

[0024] S5.2: primary degumming, using plasma degumming to degumming the bottom of the blind groove;

[0025] S5.3: Secondary debonding: performing secondary debonding on the bottom of the blind groove by using chemical debonding, and roughening the upper surface of the upper insulating layer and the lower surface of the lower insulating layer.

[0026] According to some embodiments of the present invention, step S6 includes: adjusting the charge of the upper surface of the upper insulating layer, the lower surface of the lower insulating layer, the semi-cured sheet layer located on the wall of the through hole, and the semi-cured sheet layer located on the inner wall of the blind groove by using an alkaline pore-forming agent, and then depositing a layer of activation factor on the upper surface of the upper insulating layer and the lower surface of the lower insulating layer, the wall of the through hole and the inner wall of the blind groove by physical adsorption, wherein the activation factor is palladium ions, and then drying the multilayer board.

[0027] According to some embodiments of the present invention, step S7 includes:

[0028] S7.1: pickling, pickling the inner core plate assembly with sulfuric acid;

[0029] S7.2: Paste dry film, paste dry film on the upper surface of the upper insulating layer and the lower surface of the lower insulating layer, the film pasting temperature is 110±5℃, and the film pasting pressure is 4.0±1.0kg / cm2;

[0030] S7.3: Exposure: Use LDI exposure equipment to expose the non-line area, and the JE / PE value is 25 / 25um;

[0031] S7.4: Developing, using a sodium carbonate system developer to remove the portion of the dry film covering the outer circuit area, the blind groove and the through hole.

[0032] According to some embodiments of the present invention, in the step S4, the processing depth of the blind groove is 100μm; in the step S8, a high-speed copper deposition method is adopted, the copper deposition equipment is a gantry vertical copper deposition equipment, the copper deposition time is 60min, the copper thickness of the outer layer circuit formed in the outer layer circuit area is h1, h1=40μm, and the thickness of the first copper layer formed on the bottom wall of the blind groove is h2, h2≥35μm.

[0033] The millimeter wave radar circuit board according to the embodiment of the present invention is formed by processing the millimeter wave radar circuit board using the processing method of any of the above embodiments.

[0034] The millimeter wave radar circuit board according to the embodiment of the present invention has at least the following beneficial effects:

[0035] By adopting the processing method of the millimeter-wave radar circuit board in any of the above embodiments, a plurality of independent blind hole structures in the traditional structure can be replaced by a continuous blind groove, thereby forming a continuous RF circuit pattern, effectively increasing the signal shielding area, and making the millimeter-wave radar circuit board have a better signal shielding effect. In addition, the millimeter-wave radar circuit board of the embodiment of the present invention eliminates the processes of multiple electroplating, single-sided copper reduction, and circuit etching in the traditional processing method during processing, and can directly realize the production of the outer layer circuit, the first copper layer, and the second copper layer through activation and copper deposition, which greatly shortens the processing flow of the millimeter-wave radar circuit board and improves the production efficiency of the millimeter-wave radar circuit board.

[0036] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0038] Figure 1 Schematic diagram of stacking boards in step S2 of the method for processing a millimeter wave radar circuit board according to an embodiment of the present invention;

[0039] Figure 2 Schematic diagram of removing the resist film in step S2 of the method for processing a millimeter wave radar circuit board according to an embodiment of the present invention;

[0040] Figure 3 A schematic diagram of a multilayer board of a millimeter wave radar circuit board processing method according to an embodiment of the present invention;

[0041] Figure 4 Schematic diagram of mechanical drilling and laser blind vias in steps S3 and S4 of a method for processing a millimeter wave radar circuit board according to an embodiment of the present invention;

[0042] Figure 5 It is a schematic diagram of activation, exposure and development in steps S6 and S7 of the processing method of the millimeter wave radar circuit board according to an embodiment of the present invention;

[0043] Figure 6 Schematic diagram of copper deposition in step S8 of the method for processing a millimeter wave radar circuit board according to an embodiment of the present invention;

[0044] Figure 7 Schematic diagram of step S9 of the method for processing a millimeter wave radar circuit board according to an embodiment of the present invention.

[0045] Reference numerals:

[0046] Multilayer board 100, inner core board assembly 110, copper substrate 111, prepreg layer 112, upper insulating layer 120, lower insulating layer 130, adhesive resist 140, activation factor 150, dry film 160, outer layer circuit area 170, outer layer circuit 171, shielding layer 180;

[0047] Through hole 200, first copper layer 210;

[0048] Blind slot 300 and second copper layer 310 . DETAILED DESCRIPTION

[0049] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0050] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0051] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0052] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0053] By adopting the processing method of the millimeter wave radar circuit board of the embodiment of the present invention, the upper insulating layer 120 and the lower insulating layer 130 are used to replace the copper foil on the upper and lower surfaces of the inner core board component 110 in the traditional pressing process during pressing, that is, the upper insulating layer 120 and the lower insulating layer 130 are pressed correspondingly on the upper and lower sides of the inner core board component 110, and then the through hole 200 is processed by mechanical drilling, and the blind groove 300 is processed by CO2 ablation. After mechanical drilling and laser blind groove 300, a layer of activation factor 150 can be directly deposited on the upper surface of the upper insulating layer 120, the lower surface of the lower insulating layer 130, the wall of the through hole 200 and the inner wall of the blind groove 300 by activation to form an activation layer, so that it is convenient to directly form an outer layer circuit 171 in the outer layer circuit area 170 by copper deposition, form a first copper layer 210 on the inner wall of the blind groove 300, and form a second copper layer 310 on the inner wall of the through hole 200. In the processing method, the signal shielding method is to open a continuous blind groove 300 extending to the shielding layer 180, and then form the first copper layer 210 in the blind groove 300 by copper deposition, that is, a continuous blind groove 300 is used to replace the multiple independent blind hole structures in the traditional structure, thereby forming a continuous RF circuit pattern, effectively increasing the signal shielding area, so that the millimeter wave radar circuit board has a better signal shielding effect. In addition, the processing method of the embodiment of the present invention also eliminates the processes of multiple electroplating, single-sided copper reduction, and circuit etching in the traditional processing method, and can directly realize the production of the outer layer circuit 171, the first copper layer 210, and the second copper layer 310 by activation and copper deposition, which greatly shortens the processing flow of the millimeter wave radar circuit board and improves the production efficiency of the millimeter wave radar circuit board.

[0054] It is understandable that, referring to Figures 1 to 7 The inner core board assembly 110 may specifically include four layers of copper substrates 111 and three layers of semi-cured film layers 112. Of course, in addition to this, the number of copper substrates 111 in the inner core board assembly 110 may also be two, three, five or more, which is not specifically limited in the present invention. In addition, since an upper insulating layer 120 is set on the upper surface of the inner core board assembly 110 and a lower insulating layer 130 is set on the lower surface of the inner core board assembly 110 during pressing, when the inner core board assembly 110 is stacked, the copper substrates 111 may be placed on both the uppermost and lowermost layers. Of course, in addition to this, semi-cured films may also be placed on both the uppermost and lowermost layers, or one of the uppermost and lowermost layers may be a semi-cured film layer 112 and the other may be a copper substrate 111. The present invention does not specifically limit this. It is only necessary that all copper substrates 111 and semi-cured film layers 112 are staggered and stacked to form the inner core board assembly 110.

[0055] It can be understood that by adopting the processing method of the millimeter-wave radar circuit board of the embodiment of the present invention, the surface of the multilayer board 100 after pressing is an upper insulating layer 120 and a lower insulating layer 130, and there is no copper foil. Therefore, when mechanical drilling is performed in step S3, it is necessary to strictly control the cutting speed. Compared with mechanical drilling on a circuit board with a copper foil surface, the embodiment of the present invention directly starts drilling from the upper insulating layer 120 or the lower insulating layer 130, which is beneficial to prolonging the life of the drill bit.

[0056] It is understandable that in step S4, since the surface of the laminated multilayer board 100 is the upper insulating layer 120 and the lower insulating layer 130, there is no copper foil to reflect the laser and resist corrosion, so the blind groove 300 can be processed by direct CO2 ablation.

[0057] It can be understood that the upper insulating layer 120 and the lower insulating layer 130 can specifically be PP layers. Specifically, the upper insulating layer 120 arranged on the upper surface of the inner core board assembly 110 can be resin PP coated on the upper surface of the inner core board assembly 110, and the lower insulating layer 130 arranged on the lower surface of the inner core board assembly 110 can specifically use FR4PP material. This embodiment of the present invention does not make any specific limitation on this.

[0058] It is understandable that in step S9, the post-process may specifically include processes such as solder resist, surface treatment, and molding in the conventional processing flow of the circuit board, which is not specifically limited in this embodiment of the present invention.

[0059] Reference Figure 1 and Figure 2In some embodiments, step S2 further includes: attaching a resistive film 140 to the upper surface of the upper insulating layer 120 and the lower surface of the lower insulating layer 130, pressing the stacked resistive film 140, the upper insulating layer 120, the inner core board assembly 110, and the lower insulating layer 130, and removing the two resistive films 140 after pressing.

[0060] By adopting the above-mentioned processing method, since the upper insulating layer 120 and the lower insulating layer 130 are used to replace the copper foil on the upper and lower surfaces of the inner core board assembly 110 in the traditional pressing process during pressing, the resistive film 140 can be attached to the surface of the upper insulating layer 120 and the lower insulating layer 130 during pressing. The resistive film 140 has good temperature resistance, separability and chemical stability, and can prevent adhesion between the pressing plate, the upper insulating layer 120, and the support plate and the lower insulating layer 130 during pressing. In addition, it can also block external moisture, oxygen, dust, etc., thereby protecting the pressing of the multilayer board 100 and reducing the influence of the external environment on the multilayer board 100 during the pressing process.

[0061] It is understandable that when removing the adhesive resistance film 140, you can adopt the method of starting to tear it off from the two corners of the same side at the same time, maintaining a uniform speed during the entire film tearing process to avoid strong pulling at a single corner. After tearing the film, it is also necessary to check whether there are any residual film fragments on the surface of the upper insulating layer 120 and the lower insulating layer 130.

[0062] In some embodiments, in step S2, the pressing process is divided into 10 sections, and at least one parameter of the temperature, time, and pressure of two adjacent pressing processes is adjusted; vacuuming is performed in sections 1 to 8, the vacuum setting value is <30mbar, and the total pressing time from section 1 to section 10 is 180min-220min; vacuuming is stopped in section 9, and the vacuum is released in section 10, the pressing time of section 9 is 45min, and the pressing time of section 10 is 20min.

[0063] By adopting the above processing method, the lamination process is divided into 10 stages, so that the temperature, time and pressure parameters of two adjacent lamination processes can be flexibly adjusted to achieve a better lamination effect. In addition, by performing a vacuum operation in the first 8 lamination processes, that is, by applying pressure and heat to the multilayer board 100 in a vacuum environment, the generation of bubbles and gaps can be effectively reduced, which is conducive to improving the lamination quality of the multilayer board 100. In addition, the vacuum condition can reduce the occurrence of oxidation and other chemical changes, which is conducive to maintaining the stability of the multilayer board 100.

[0064] It can be understood that in some embodiments, the pressing process is divided into 10 stages, and the specific temperature, time, and pressure parameters of each stage can refer to the following table:

[0065] Hot plate temperature (℃) Hot plate time (min) Pressure (psi) Pressure time (min) 1 120 1 200 1 2 120 14 450 14 3 140 4 550 4 4 115 5 550 5 5 115 40 550 40 6 200 11 550 12 7 200 30 550 30 8 185 10 550 10 9 185 45 550 45 10 120 20 150 20

[0066] Reference Figure 5 In some embodiments, step S6 includes: adjusting the charge of the upper surface of the upper insulating layer 120, the lower surface of the lower insulating layer 130, the semi-cured sheet layer 112 located on the hole wall of the through hole 200, and the semi-cured sheet layer 112 located on the inner wall of the blind groove 300 by using an alkaline pore-forming agent, and then depositing a layer of activation factor 150 on the upper surface of the upper insulating layer 120 and the lower surface of the lower insulating layer 130, the hole wall of the through hole 200 and the inner wall of the blind groove 300 by physical adsorption, wherein the activation factor 150 is palladium ions, and then the multilayer board 100 is dried.

[0067] By adopting the above method, the charge of the upper surface of the upper insulating layer 120, the lower surface of the lower insulating layer 130, the prepreg layer 112 located on the hole wall of the through hole 200, and the prepreg layer 112 located on the inner wall of the blind groove 300 is adjusted by using an alkaline pore-forming agent, so that the upper insulating layer 120, the lower insulating layer 130, the inner wall of the through hole 200, and the inner wall of the blind groove 300 can more easily adsorb the activation factor 150. Subsequently, a layer of palladium ions is deposited on the upper surface of the upper insulating layer 120, the lower surface of the lower insulating layer 130, the prepreg layer 112 located on the hole wall of the through hole 200, and the prepreg layer 112 located on the inner wall of the blind groove 300 by physical adsorption, so that the subsequent copper deposition process can be facilitated.

[0068] It can be understood that since the embodiment of the present invention adopts palladium ions as the activation factor 150, palladium ions are usually positively charged. Therefore, the charge of the upper surface of the upper insulating layer 120, the lower surface of the lower insulating layer 130, the semi-cured sheet layer 112 located on the hole wall of the through hole 200, and the semi-cured sheet layer 112 located on the inner wall of the blind groove 300 can be adjusted to be negatively charged through an alkaline pore-forming agent, thereby making it easier for the upper insulating layer 120, the lower insulating layer 130, the inner wall of the through hole 200 and the inner wall of the blind groove 300 to adsorb palladium ions.

[0069] It is understandable that, in addition to palladium ions, the activation factor 150 may also be nano-metal particles, etc., and the present invention does not specifically limit this. In addition, for the positively charged activation factor 150, it is necessary to adjust the charge of the upper surface of the upper insulating layer 120, the lower surface of the lower insulating layer 130, the semi-cured sheet layer 112 located at the hole wall of the through hole 200, and the semi-cured sheet layer 112 located at the inner wall of the blind groove 300 to be negatively charged; for the negatively charged activation factor 150, it is necessary to adjust the charge of the upper surface of the upper insulating layer 120, the lower surface of the lower insulating layer 130, the semi-cured sheet layer 112 located at the hole wall of the through hole 200, and the semi-cured sheet layer 112 located at the inner wall of the blind groove 300 to be positively charged.

[0070] Reference Figures 5 to 7In some embodiments, step S7 includes:

[0071] S7.1: pickling, using sulfuric acid to pickle the inner core plate assembly 110;

[0072] S7.2: attaching the dry film 160 to the upper surface of the upper insulating layer 120 and the lower surface of the lower insulating layer 130, the film attaching temperature is 110±5°C, and the film attaching pressure is 4.0±1.0kg / cm2;

[0073] S7.3: Exposure: Use LDI exposure equipment to expose the non-line area, and the JE / PE value is 25 / 25um;

[0074] S7.4: Development, using a sodium carbonate system developer to remove the portion of the dry film 160 covering the outer circuit area 170, the blind groove 300 and the through hole 200.

[0075] By adopting the above processing method, after the dry film 160 is attached, the non-circuit area on the upper insulating layer 120 and the lower insulating layer 130 is exposed, and then the dry film 160 at the outer circuit area 170, the blind groove 300 and the through hole 200 on the upper insulating layer 120 and the lower insulating layer 130 is dissolved by a developer, so that the outer circuit area 170, the blind groove 300 and the through hole 200 on the surface of the multilayer board 100 that need to be copper plated are exposed, and the non-circuit area that does not need copper plated is shielded by the dry film 160, thereby facilitating the subsequent copper plated operation on the outer circuit area 170, the inner wall of the blind groove 300 and the inner wall of the through hole 200.

[0076] It is understandable that the non-circuit area specifically refers to the area on the upper insulating layer 120 and the lower insulating layer 130 where no circuits are designed, and the outer circuit area 170 specifically refers to the area on the upper insulating layer 120 and the lower insulating layer 130 where outer circuits 171 are designed.

[0077] It is understandable that in the pickling process of step S7.1, since the surface of the multilayer board 100 is the upper insulating layer 120 and the lower insulating layer 130, rather than the copper foil, sulfuric acid can be directly used as the pickling solution without adding a micro-etching factor or etching solution.

[0078] Reference Figure 6 In some embodiments, in step S4, the processing depth of the blind groove 300 is 100 μm; in step S8, a high-speed copper deposition method is adopted, the copper deposition equipment is a gantry vertical copper deposition equipment, the copper deposition time is 60 min, and the copper thickness of the outer layer circuit 171 formed in the outer layer circuit area 170 is h1, h1=40 μm, and the thickness of the first copper layer 210 formed on the bottom wall of the blind groove 300 is h2, h2≥35 μm.

[0079] By adopting the above processing method, copper can be conveniently deposited on the outer circuit area 170, the inner wall of the blind groove 300 and the inner wall of the through hole 200, thereby facilitating the production of the outer circuit 171, the first copper layer 210 and the second copper layer 310. By processing the copper thickness h1 of the outer circuit 171 to 40μm, the electrical performance of the millimeter-wave radar circuit board can be improved. By setting the processing thickness of the blind groove 300 to 100μm and processing the thickness of the first copper layer 210 on the bottom wall of the blind groove 300 to h2≥35μm, it is beneficial to improve the signal shielding effect of the millimeter-wave radar circuit board.

[0080] An embodiment of the present invention further provides a millimeter wave radar circuit board, which is formed by processing the millimeter wave radar circuit board using the processing method of any of the above embodiments.

[0081] In the millimeter wave radar circuit board of the embodiment of the present invention, by adopting the processing method of the millimeter wave radar circuit board in any of the above embodiments, a plurality of independent blind hole structures in the traditional structure can be replaced by a continuous blind slot 300, thereby forming a continuous RF circuit pattern, effectively increasing the signal shielding area, so that the millimeter wave radar circuit board has a better signal shielding effect. In addition, the millimeter wave radar circuit board of the embodiment of the present invention eliminates the processes of multiple electroplating, single-sided copper reduction, and circuit etching in the traditional processing method during processing, and can directly realize the production of the outer layer circuit 171, the first copper layer 210, and the second copper layer 310 through activation and copper deposition, which greatly shortens the processing flow of the millimeter wave radar circuit board and improves the production efficiency of the millimeter wave radar circuit board.

[0082] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for processing a millimeter wave radar circuit board, characterized in that: The following steps are involved: S1: obtaining at least two copper substrates (111), and fabricating inner-layer circuits on the copper substrates (111); S2: Pressing the plate, stacking all the copper substrates (111) and the prepreg layers (112) alternately to form an inner core board assembly (110), arranging an upper insulating layer (120) on the upper surface of the inner core board assembly (110), arranging a lower insulating layer (130) on the lower surface of the inner core board assembly (110), and pressing the upper insulating layer (120), the inner core board assembly (110) and the lower insulating layer (130) to form a multilayer board (100); S3: Mechanical drilling to form a through hole (200) penetrating the multilayer board (100); S4: laser blind grooves (300), wherein one of the copper substrates (111) is a shielding layer (180), and a CO2 ablation method is used to process a blind groove (300) extending downward to the shielding layer (180) on the upper surface of the upper insulating layer (120), wherein the blind grooves (300) are arranged continuously to form a radio frequency circuit pattern; S5: removing glue, removing the residual glue at the bottom of the blind groove (300); S6: Activation, depositing a layer of activation factor (150) on the upper surface of the upper insulating layer (120), the lower surface of the lower insulating layer (130), the wall of the through hole (200) and the inner wall of the blind groove (300) to form an activation layer; S7: exposing and developing, attaching a dry film (160) to the upper surface of the upper insulating layer (120) and the lower surface of the lower insulating layer (130), and exposing and developing to reveal the outer circuit area (170), the blind groove (300) and the through hole (200); S8: copper deposition to form an outer layer circuit (171) in the outer layer circuit area (170), to form a first copper layer (210) on the inner wall of the blind groove (300), and to form a second copper layer (310) on the inner wall of the through hole (200); S9: film stripping, removing the dry film (160) on the surface of the inner core plate assembly (110); S10: Post-process.

2. The method for processing a millimeter wave radar circuit board according to claim 1, characterized in that: The step S2 also includes: attaching a resistive film (140) to the upper surface of the upper insulating layer (120) and the lower surface of the lower insulating layer (130), pressing the stacked resistive film (140), the upper insulating layer (120), the inner core board assembly (110), and the lower insulating layer (130), and removing the two resistive films (140) after pressing.

3. The method for processing a millimeter wave radar circuit board according to claim 2, characterized in that: In the step S2, the pressing process is divided into 10 sections, and at least one parameter among the temperature, time and pressure of two adjacent pressing processes is adjusted; The vacuum operation is performed in the first to eighth sections, the vacuum setting value is less than 30mbar, and the total pressing time of the first to tenth sections is 180min-220min; the vacuum operation is stopped in the ninth section, and the vacuum is released in the tenth section. The pressing time of the ninth section is 45min, and the pressing time of the tenth section is 20min.

4. The method for processing a millimeter wave radar circuit board according to claim 3, characterized in that: The thickness of the shielding layer (180) is C, C≥25μm, the ablation depth of the blind groove (300) on the shielding layer (180) in step S4 is c, c≤3μm, the top width of the blind groove (300) is a, the bottom width is b, 0.8≤a / b≤1.

5. The method for processing a millimeter wave radar circuit board according to claim 4, characterized in that: The blind groove (300) is processed by stacking hole ablation, and the CO2 ablation process is divided into 7 shots, the pulse energy of each shot is 28 mj, the beam diameter is 3 mm, wherein the pulse width of the first shot is 18 μs, the pulse width of the second to fourth shots is 10 μs, and the pulse width of the fifth to seventh shots is 8 μs.

6. The method for processing a millimeter wave radar circuit board according to claim 5, characterized in that: The step S5 comprises: S5.1: grinding the plate to remove burrs at the through hole (200) and the blind groove (300), and grinding the upper surface of the upper insulating layer (120) and the lower surface of the lower insulating layer (130); S5.2: primary debonding, using plasma debonding to debond the bottom of the blind groove (300); S5.3: Secondary debonding: performing secondary debonding on the bottom of the blind groove (300) by using chemical debonding, and roughening the upper surface of the upper insulating layer (120) and the lower surface of the lower insulating layer (130).

7. The method for processing a millimeter wave radar circuit board according to claim 1, characterized in that: The step S6 comprises: adjusting the charge of the upper surface of the upper insulating layer (120), the lower surface of the lower insulating layer (130), the semi-cured sheet layer (112) located on the hole wall of the through hole (200), and the semi-cured sheet layer (112) located on the inner wall of the blind groove (300) by using an alkaline pore-forming agent, and then depositing a layer of activation factor (150) on the upper surface of the upper insulating layer (120), the lower surface of the lower insulating layer (130), the hole wall of the through hole (200), and the inner wall of the blind groove (300) by physical adsorption, wherein the activation factor (150) is palladium ions, and then drying the multilayer board (100).

8. The method for processing a millimeter wave radar circuit board according to claim 1, characterized in that: The step S7 comprises: S7.1: pickling, using sulfuric acid to pickle the inner core plate assembly (110); S7.2: Pasting a dry film (160), pasting the dry film (160) on the upper surface of the upper insulating layer (120) and the lower surface of the lower insulating layer (130), the film pasting temperature is 110±5°C, and the film pasting pressure is 4.0±1.0kg / cm2; S7.3: Exposure: Use LDI exposure equipment to expose the non-line area, and the JE / PE value is 25 / 25um; S7.4: Developing, using a sodium carbonate system developer to remove the portion of the dry film (160) covering the outer circuit area (170), the blind groove (300) and the through hole (200).

9. The method for processing a millimeter wave radar circuit board according to claim 1, characterized in that: In the step S4, the processing depth of the blind groove (300) is 100 μm; In the step S8, a high-speed copper deposition method is adopted, the copper deposition equipment is a gantry vertical copper deposition equipment, the copper deposition time is 60 minutes, the copper thickness of the outer layer circuit (171) formed in the outer layer circuit area (170) is h1, h1=40μm, and the thickness of the first copper layer (210) formed on the bottom wall of the blind groove (300) is h2, h2≥35μm.

10. The millimeter wave radar circuit board according to claim 1, characterized in that: The millimeter wave radar circuit board is formed by the processing method of any one of claims 1 to 9.

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