An ultra-thin high-low copper integrated boss PCB structure and a manufacturing process thereof

Abstract

This invention discloses an ultra-thin high- and low-copper integrated boss PCB structure and its manufacturing process, specifically relating to the field of PCB precision manufacturing technology. The structure includes: an ultra-thin resin substrate with a thickness of 0.1 mm; multiple rows of parallel high- and low-copper composite structure groups disposed on the surface of the ultra-thin resin substrate, each group comprising a linearly arranged boss structure, each boss structure consisting of a high-copper layer and a low-copper layer, which are integrally formed through a layered electroplating process; and cutting alignment marks disposed on the four edges of the ultra-thin resin substrate. This invention integrates the high-copper and low-copper layers onto the ultra-thin resin substrate through layered electroplating, completely eliminating the mechanical connection interface of traditional assembled structures and fundamentally avoiding failure risks such as microcracks and increased contact resistance caused by differences in thermal expansion coefficients and vibration impacts.

Description

Technical Field

[0001] This invention relates to the field of PCB precision manufacturing technology, specifically to an ultra-thin high and low copper integrated boss PCB structure and its manufacturing process. Background Technology

[0002] As electronic devices become smaller and lighter, higher demands are placed on the size and performance of their internal components. As a core component in electronic circuits, the precision and reliability of the capacitor's internal structure directly affect the overall performance of the device.

[0003] Traditional capacitor electrode connection structures typically employ machining or assembly to create stepped surfaces with varying heights, resulting in a mechanical interface between high-copper and low-copper components. Over long-term use, this structure is prone to microcracks or increased contact resistance at the interface due to differences in thermal expansion coefficients and mechanical vibration, leading to capacitor failure. Furthermore, the internal electrode connections require precise high- and low-copper boss structures, with the height difference typically controlled within approximately 200 μm, and extremely high coplanarity requirements for the entire board of bosses. Traditional machining methods struggle to achieve such high-precision three-dimensional structures on ultra-thin substrates and are inefficient. Summary of the Invention

[0004] The purpose of this invention is to provide an ultra-thin high-low copper integrated boss PCB structure and its manufacturing process to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an ultra-thin high-low copper integrated boss PCB structure, comprising:

[0006] An ultra-thin resin substrate, wherein the thickness of the ultra-thin resin substrate is 0.1 mm;

[0007] Multiple rows of parallel high and low copper composite structures are disposed on the surface of the ultra-thin resin substrate. Each high and low copper composite structure group includes a boss structure arranged in a straight line. The boss structure is composed of a high copper layer and a low copper layer. The high copper layer and the low copper layer are integrally formed by a layered coating electroplating process.

[0008] Cutting alignment marks are provided on the four edges of the ultra-thin resin substrate, and the cutting alignment marks are aligned with the gap area of ​​the adjacent boss structure.

[0009] Furthermore, the thickness of the high copper layer is 300±10μm, the thickness of the low copper layer is 100±10μm, the height difference between the high copper layer and the low copper layer is 200μm, the positional tolerance between the high copper layer and the low copper layer is less than 50μm, and the high copper layer and the low copper layer are connected by micro-etching and leveling to form a smooth transition.

[0010] Furthermore, the surface flatness of the high copper layer and the low copper layer is less than 50 μm, the coplanarity of all the boss structures on the ultrathin resin substrate is 10-15 μm, and the water droplet angle on the surface of the boss structure is not greater than 15°.

[0011] This invention provides a manufacturing process for the aforementioned ultra-thin high-low copper integrated boss PCB structure, which specifically includes the following steps:

[0012] S1, Substrate preparation: Provide an ultra-thin resin substrate with a thickness of 0.1mm, and use an ultraviolet laser to process cutting alignment marks in the gap areas of the four sides of the ultra-thin resin substrate and the corresponding preset positions of adjacent boss structures.

[0013] S2, Add support: A frame support structure is connected by multiple connecting bridges in the outer edge area of ​​the surface of the ultra-thin resin substrate. The frame support structure includes a rectangular outer frame and multiple parallel horizontal bars disposed inside the rectangular outer frame. The horizontal bars are located between preset positions of two adjacent rows of boss structures.

[0014] S3, Surface roughening: The surface of the ultrathin resin substrate is roughened by grinding;

[0015] S4, layered coating electroplating molding:

[0016] S4-1, First, a first dry film is applied to an ultra-thin resin substrate, and then the substrate is exposed and developed to reveal the outline area of ​​the pre-set position of the boss structure.

[0017] S4-2, a low copper layer of 100±10μm is formed by electroplating in the exposed boss structure outline area;

[0018] S4-3, apply the second dry film, and expose the high copper area pattern through exposure and development;

[0019] S4-4, continue electroplating copper layers on the high copper area pattern, so that the total copper layer thickness reaches 300±10μm, forming a high copper layer;

[0020] S4-5, remove residual dry film to expose the low copper layer area;

[0021] S4-6, perform micro-etching and leveling treatment to create a smooth transition between the high copper layer and the low copper layer and eliminate steps;

[0022] S5, Coplanar grinding of bosses: Selective grinding of the high copper layer and low copper layer is carried out using a special boss grinding equipment to control the surface flatness of a single boss to be less than 50μm and the coplanarity of the bosses on the whole board to be 10-15μm.

[0023] S6, Pattern Exposure and Etching: Pattern exposure is performed using LDI laser direct imaging technology. Coordinate laser scanning exposure selectively exposes the circuit pattern on the surfaces of the high copper layer and the low copper layer, eliminating the need for a film mask and controlling the alignment accuracy within ±10μm. Pattern etching is then performed to form the required conductive lines and boss array.

[0024] S7, Three-level cleaning: The board surface is cleaned in three levels using DI pure water, ultrapure water and plasma cleaning in sequence, and the water droplet angle on the boss surface is controlled to be no more than 15°.

[0025] S8, Remove the frame support structure: Remove the frame support structure and connecting bridge in one mechanical peeling to obtain an ultra-thin high and low copper integrated boss PCB board;

[0026] S9, Finished Product Inspection: Perform boss height tolerance inspection, coplanarity inspection, positional tolerance inspection, water droplet angle inspection, and welding reliability test. After passing the inspection, mark and put into storage.

[0027] Furthermore, the connecting bridge is an epoxy resin dot with a thickness of 20-50μm or an adhesive tape with a width of 0.5-2mm. The rectangular outer frame and the horizontal bar are integrally formed. The rectangular outer frame, the horizontal bar, and the connecting bridge are an integrated temporary support structure that can be mechanically peeled off in one go. The width of the rectangular outer frame is 5-10mm, and the width of the horizontal bar is 2-5mm.

[0028] Furthermore, in the layered coating electroplating process of S4, both the first dry film and the second dry film are negative liquid photoresist dry films, and both exposures are performed using an LDI laser direct imaging system.

[0029] Furthermore, before the bosses of S5 are coplanarly ground, they need to be annealed under nitrogen protection to eliminate electroplating stress.

[0030] Furthermore, the boss grinding equipment includes: a vacuum adsorption platform, a pressure sensor array, an online thickness monitoring system, and grinding components;

[0031] The grinding assembly includes a first non-woven fabric grinding section and a second ceramic brush grinding section. The vacuum adsorption platform adsorbs and fixes the ultra-thin resin substrate through a vacuum hole array. The thickness online monitoring system uses the laser triangulation principle to monitor the surface height of each boss in real time.

[0032] During the grinding process, the grinding pressure is dynamically adjusted through a PID algorithm based on the feedback signal from the online thickness monitoring system to achieve closed-loop control, ensuring that the surface flatness of a single boss is less than 50μm and the coplanarity of the bosses on the entire board is 10-15μm.

[0033] Furthermore, in S8, the height difference between the high copper layer and the low copper layer on the ultra-thin high and low copper integrated boss PCB is 200μm, and the positional tolerance between the high copper layer and the low copper layer is less than 50μm.

[0034] Furthermore, the finished product inspection in S9 specifically includes:

[0035] The height tolerance of the boss is detected by a contact height gauge or a laser scanning microscope. The height tolerance of the high copper layer is ±10μm, and the height tolerance of the low copper layer is ±8μm.

[0036] The coplanarity of the bosses on the entire plate was checked using a white light interferometer or a confocal microscope.

[0037] The positional tolerance of the boss was detected using a 2D image measuring instrument.

[0038] A contact angle meter was used to measure the water droplet angle.

[0039] The technical effects and advantages provided by the present invention in the above technical solution are as follows:

[0040] 1. The high copper layer and the low copper layer are integrally formed and fixed on the ultra-thin resin substrate through layered electroplating, which completely eliminates the mechanical connection interface of the traditional assembly structure and avoids the failure risk caused by differences in thermal expansion coefficients, vibration and impact, micro-cracks, increased contact resistance, etc. from the root.

[0041] 2. By introducing a frame support structure that can be mechanically peeled off in one go, and using connecting bridges to temporarily connect the ultra-thin resin substrate to the frame support structure, it provides overall rigid support during processing such as electroplating and grinding, effectively preventing the warping and deformation of the ultra-thin resin substrate.

[0042] 3. Employing LDI laser direct imaging technology eliminates the need for film masks, completely eliminating alignment deviations caused by film distortion;

[0043] 4. The board surface is cleaned in three stages: DI pure water, ultrapure water, and plasma cleaning. DI pure water removes grinding residues, ultrapure water removes ionic impurities, and plasma cleaning removes organic contaminants and activates the surface. The three cleaning stages work together to control the water droplet angle below 15°, ensuring the wettability and reliability of subsequent encapsulation and soldering. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0045] Figure 1This is a schematic diagram of the overall structure of the present invention;

[0046] Figure 2 For the present invention Figure 1 Enlarged schematic diagram of part A;

[0047] Figure 3 This is a flowchart of the manufacturing process steps of the present invention;

[0048] Figure 4 This is a detailed flowchart of the manufacturing process S4 of the present invention;

[0049] Figure 5 This is a schematic diagram of the entire PCB board before the frame support structure is removed, according to the present invention.

[0050] Explanation of reference numerals in the attached figures:

[0051] 1. Ultra-thin resin substrate; 2. Boss structure; 3. High copper layer; 4. Low copper layer; 5. Cutting alignment marks; 6. Frame support structure; 7. Rectangular outer frame; 8. Horizontal bar. Detailed Implementation

[0052] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0053] This invention provides, for example Figures 1 to 2 The ultra-thin high and low copper integrated boss PCB structure shown includes:

[0054] Ultra-thin resin substrate 1, the thickness of ultra-thin resin substrate 1 is 0.1mm;

[0055] Multiple rows of parallel high and low copper composite structures are set on the surface of the ultra-thin resin substrate 1. Each high and low copper composite structure group includes a boss structure 2 arranged in a straight line. The boss structure 2 is composed of a high copper layer 3 and a low copper layer 4. The high copper layer 3 and the low copper layer 4 are integrally formed by a layered coating electroplating process.

[0056] Cutting alignment marks 5 are set on the four sides of the ultra-thin resin substrate 1, and the cutting alignment marks 5 are aligned with the gap area of ​​the adjacent boss structure 2.

[0057] The thickness of the high copper layer 3 is 300±10μm, the thickness of the low copper layer 4 is 100±10μm, the height difference between the high copper layer 3 and the low copper layer 4 is 200μm, the positional tolerance between the high copper layer 3 and the low copper layer 4 is less than 50μm, and the high copper layer 3 and the low copper layer 4 are connected by micro-etching and leveling to form a smooth transition.

[0058] The surface flatness of the high copper layer 3 and the low copper layer 4 is less than 50 μm, the coplanarity of all the boss structures 2 on the ultrathin resin substrate 1 is 10-15 μm, and the water droplet angle on the surface of the boss structure 2 is not greater than 15°.

[0059] This ultra-thin high and low copper integrated boss PCB structure completely eliminates the mechanical connection interface of traditional assembly structures by fixing the high copper layer and the low copper layer to the ultra-thin resin substrate through layered electroplating. This avoids the risk of failure caused by differences in thermal expansion coefficients, vibration and impact, microcracks, and increased contact resistance.

[0060] When using this ultra-thin high and low copper integrated boss PCB structure, a cutting device is used to align the cutting alignment mark 5 and cut the ultra-thin high and low copper integrated boss PCB board to obtain individual boss structures 2. The boss structures 2 are used as the conductive electrode structure inside the multilayer chip ceramic capacitor and are finally packaged into a cuboid capacitor.

[0061] like Figures 1 to 5 As shown, the present invention provides a manufacturing process for the above-mentioned ultra-thin high and low copper integrated boss PCB structure, which specifically includes the following steps:

[0062] S1, Substrate preparation: Provide an ultra-thin resin substrate 1 with a thickness of 0.1mm, and use an ultraviolet laser to process cutting alignment marks 5 on the four sides of the ultra-thin resin substrate 1 and in the gap area corresponding to the preset position of the adjacent boss structure 2.

[0063] S2, Add support: The frame support structure 6 is connected to the outer edge area of ​​the ultra-thin resin substrate 1 by multiple connecting bridges. The connecting bridges are epoxy resin dots with a thickness of 20-50μm or tape with a width of 0.5-2mm. The frame support structure 6 includes a rectangular outer frame 7 and multiple parallel horizontal bars 8 set inside the rectangular outer frame 7. The horizontal bars 8 are located between the preset positions of two adjacent rows of boss structures 2. The rectangular outer frame 7 and the horizontal bars 8 are integrally formed. The rectangular outer frame 7, the horizontal bars 8 and the connecting bridges are an integrated temporary support structure that can be mechanically peeled off in one go. The width of the rectangular outer frame 7 is 5-10mm and the width of the horizontal bars 8 is 2-5mm.

[0064] The frame support structure 6 provides rigid support for the ultra-thin resin substrate 1 to prevent warping and deformation during subsequent processing.

[0065] S3, Surface roughening: The surface of the ultra-thin resin substrate 1 is roughened by grinding;

[0066] S4, layered coating electroplating molding:

[0067] S4-1, First, a first negative liquid photoresist dry film is applied to the ultra-thin resin substrate 1, and then an LDI laser direct imaging system is used to expose and develop the contour area of ​​the boss structure 2 at the preset position.

[0068] S4-2, A low copper layer 4 of 100±10μm is formed by electroplating in the outline area of ​​the exposed boss structure 2.

[0069] S4-3, a second negative liquid photoresist dry film is applied, and the high copper area pattern is exposed and developed using an LDI laser direct imaging system;

[0070] S4-4, continue electroplating copper layers on the high copper area pattern to make the total copper layer thickness reach 300±10μm, forming high copper layer 3;

[0071] S4-5, remove residual dry film to expose area 4 of the low copper layer;

[0072] S4-6, perform micro-etching and leveling treatment to create a smooth transition between the high copper layer 3 and the low copper layer 4, eliminating steps;

[0073] S5, coplanar grinding of bosses:

[0074] Before grinding, annealing is performed under nitrogen protection to eliminate electroplating stress;

[0075] A dedicated boss grinding equipment is used to selectively grind the high copper layer 3 and the low copper layer 4, controlling the surface flatness of a single boss to be less than 50μm and the coplanarity of the bosses on the whole board to be 10-15μm.

[0076] The boss grinding equipment includes: a vacuum adsorption platform, a pressure sensor array, an online thickness monitoring system, and grinding components;

[0077] The grinding assembly includes a first non-woven fabric grinding section and a second ceramic brush grinding section. The vacuum adsorption platform adsorbs and fixes the ultra-thin resin substrate 1 through a vacuum hole array. The online thickness monitoring system uses the laser triangulation principle to monitor the surface height of each boss in real time.

[0078] During the grinding process, the grinding pressure is dynamically adjusted through a PID algorithm based on the feedback signal from the online thickness monitoring system to achieve closed-loop control, ensuring that the surface flatness of a single boss is less than 50μm and the coplanarity of the bosses on the entire board is 10-15μm.

[0079] S6, Pattern Exposure and Etching: Pattern exposure is performed using LDI laser direct imaging technology. Coordinate laser scanning exposure selectively exposes the circuit pattern on the surfaces of high copper layer 3 and low copper layer 4, without the need for a film mask. The alignment accuracy is controlled within ±10μm. Pattern etching is then performed to form the required conductive lines and boss array.

[0080] S7, Level 3 Cleaning:

[0081] First stage: Rinse with DI pure water to remove grinding residue;

[0082] Second stage: Rinse with ultrapure water to remove ionic impurities;

[0083] Level 3: Plasma cleaning is used to remove organic contaminants and activate the surface;

[0084] The three-stage cleaning process works synergistically to keep the water droplet angle below 15°.

[0085] S8, Remove the frame support structure: Remove the frame support structure 6 and the connecting bridge in one mechanical peeling to obtain an ultra-thin high and low copper integrated boss PCB board.

[0086] S9, Finished Product Inspection, specifically includes:

[0087] The height tolerance of the bosses was checked using a contact height gauge or a laser scanning microscope. The height tolerance of the high copper layer 3 was ±10μm, and the height tolerance of the low copper layer 4 was ±8μm.

[0088] The coplanarity of the bosses on the entire plate was measured to be <50μm using a white light interferometer or a confocal microscope.

[0089] The positional tolerance of the boss was measured using a 2D image measuring instrument, and the tolerance was <50μm.

[0090] The water droplet angle was measured to be ≤15° using a contact angle measuring instrument.

[0091] After passing inspection, the items are labeled and put into storage.

[0092] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An ultra-thin high-low copper integrated boss PCB structure, characterized in that, include: Ultra-thin resin substrate (1), wherein the thickness of the ultra-thin resin substrate (1) is 0.1 mm; Multiple rows of parallel high and low copper composite structures are disposed on the surface of the ultra-thin resin substrate (1). Each high and low copper composite structure group includes a boss structure (2) arranged in a straight line. The boss structure (2) is composed of a high copper layer (3) and a low copper layer (4). The high copper layer (3) and the low copper layer (4) are integrally formed by a layered coating electroplating process. Cutting alignment marks (5) are provided on the four sides of the ultra-thin resin substrate (1), and the cutting alignment marks (5) are aligned with the gap area of ​​the adjacent boss structure (2).

2. The ultra-thin high and low copper integrated boss PCB structure according to claim 1, characterized in that: The thickness of the high copper layer (3) is 300±10μm, the thickness of the low copper layer (4) is 100±10μm, the height difference between the high copper layer (3) and the low copper layer (4) is 200μm, the positional tolerance between the high copper layer (3) and the low copper layer (4) is less than 50μm, and the high copper layer (3) and the low copper layer (4) are connected by micro-etching and leveling to form a smooth transition connection.

3. The ultra-thin high and low copper integrated boss PCB structure according to claim 1, characterized in that: The surface flatness of the high copper layer (3) and the low copper layer (4) is less than 50 μm, the coplanarity of all the boss structures (2) on the ultrathin resin substrate (1) is 10-15 μm, and the water droplet angle on the surface of the boss structure (2) is not greater than 15°.

4. A manufacturing process for an ultra-thin high-low copper integrated boss PCB structure as described in claim 3, characterized in that, The manufacturing process specifically includes the following steps: S1, Substrate preparation: Provide an ultra-thin resin substrate (1) with a thickness of 0.1mm, and use an ultraviolet laser to process cutting alignment marks (5) in the gap area of ​​the four sides of the ultra-thin resin substrate (1) and the corresponding adjacent boss structure (2) at the preset position. S2, Add support: The frame support structure (6) is connected by multiple connecting bridges in the outer edge area of ​​the surface of the ultrathin resin substrate (1). The frame support structure (6) includes a rectangular outer frame (7) and multiple parallel horizontal bars (8) disposed inside the rectangular outer frame (7). The horizontal bars (8) are located between the preset positions of two adjacent rows of boss structures (2). S3, Surface roughening: The surface of the ultrathin resin substrate (1) is roughened by grinding; S4, layered coating electroplating molding: S4-1, First, a first dry film is applied to the ultra-thin resin substrate (1), and then exposed and developed to reveal the outline area of ​​the pre-set position of the boss structure (2); S4-2, a low copper layer (4) of 100±10μm is formed by electroplating in the outline area of ​​the exposed boss structure (2). S4-3, apply the second dry film, and expose the high copper area pattern through exposure and development; S4-4, continue to electroplate copper layer on the high copper area pattern, so that the total copper layer thickness reaches 300±10μm, forming a high copper layer (3). S4-5, remove residual dry film to expose the low copper layer (4) area; S4-6, perform micro-etching and leveling treatment to form a smooth transition between the high copper layer (3) and the low copper layer (4) and eliminate steps; S5, Coplanar grinding of bosses: Selective grinding of the high copper layer (3) and low copper layer (4) is carried out using a special boss grinding equipment to control the surface flatness of a single boss to be less than 50μm and the coplanarity of the bosses on the whole board to be 10-15μm; S6, Pattern Exposure and Etching: Pattern exposure is performed using LDI laser direct imaging technology. The line pattern is selectively exposed on the surface of the high copper layer (3) and low copper layer (4) by coordinate laser scanning exposure. No film mask is required, and the alignment accuracy is controlled within ±10μm. Pattern etching is then performed to form the required conductive lines and boss array. S7, Three-level cleaning: The board surface is cleaned in three levels using DI pure water, ultrapure water and plasma cleaning in sequence, and the water droplet angle on the boss surface is controlled to be no more than 15°. S8, Remove the frame support structure: Remove the frame support structure (6) and connecting bridge by mechanical peeling in one go to obtain an ultra-thin high and low copper integrated boss PCB board; S9, Finished Product Inspection: Perform boss height tolerance inspection, coplanarity inspection, positional tolerance inspection, water droplet angle inspection, and welding reliability test. After passing the inspection, mark and put into storage.

5. The manufacturing process of the ultra-thin high and low copper integrated boss PCB structure according to claim 4, characterized in that: The connecting bridge is an epoxy resin dot with a thickness of 20-50μm or a tape with a width of 0.5-2mm. The rectangular outer frame (7) and the horizontal bar (8) are integrally formed. The rectangular outer frame (7), the horizontal bar (8) and the connecting bridge are an integral temporary support structure that can be mechanically peeled off in one go. The width of the rectangular outer frame (7) is 5-10mm and the width of the horizontal bar (8) is 2-5mm.

6. The manufacturing process of the ultra-thin high and low copper integrated boss PCB structure according to claim 4, characterized in that: In the layered coating electroplating process of S4, both the first dry film and the second dry film are negative liquid photoresist dry films, and both exposures are performed using an LDI laser direct imaging system.

7. The manufacturing process of the ultra-thin high and low copper integrated boss PCB structure according to claim 4, characterized in that: Before the bosses of S5 are coplanarly ground, they need to be annealed under nitrogen protection to eliminate electroplating stress.

8. The manufacturing process of the ultra-thin high and low copper integrated boss PCB structure according to claim 4, characterized in that: The boss grinding equipment includes: a vacuum adsorption platform, a pressure sensor array, an online thickness monitoring system, and grinding components; The grinding assembly includes a first non-woven fabric grinding section and a second ceramic brush grinding section. The vacuum adsorption platform adsorbs and fixes the ultra-thin resin substrate (1) through a vacuum hole array. The thickness online monitoring system uses the laser triangulation principle to monitor the surface height of each boss in real time. During the grinding process, the grinding pressure is dynamically adjusted through a PID algorithm based on the feedback signal from the online thickness monitoring system to achieve closed-loop control, ensuring that the surface flatness of a single boss is less than 50μm and the coplanarity of the bosses on the entire board is 10-15μm.

9. The manufacturing process of the ultra-thin high and low copper integrated boss PCB structure according to claim 4, characterized in that: In S8, the height difference between the high copper layer (3) and the low copper layer (4) on the ultra-thin high and low copper integrated boss PCB is 200μm, and the positional tolerance between the high copper layer (3) and the low copper layer (4) is less than 50μm.

10. The manufacturing process of the ultra-thin high and low copper integrated boss PCB structure according to claim 4, characterized in that: The finished product inspection in S9 specifically includes: The height tolerance of the boss is detected by a contact height gauge or a laser scanning microscope. The height tolerance of the high copper layer (3) is ±10μm and the height tolerance of the low copper layer (4) is ±8μm. The coplanarity of the bosses on the entire plate was checked using a white light interferometer or a confocal microscope. The positional tolerance of the boss was detected using a 2D image measuring instrument. A contact angle meter was used to measure the water droplet angle.

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