Integrated thick GEM and manufacturing method thereof
By using pre-etching of the inner insulating ring and synchronous controlled-depth etching processes, the problem of insufficient concentricity between the copper pillar and the insulating ring in thick GEM detectors was solved, enabling stable production of miniaturized and integrated thick GEMs and improving electrical performance and reliability.
Patent Information
- Application Number
- CN202510860985.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-25
- Publication Date
- 2025-11-04
AI Technical Summary
In the production process of existing thick GEM detectors, it is difficult to achieve the required concentricity between the copper pillar and the insulating ring, resulting in inaccurate signal detection and unstable circuit connection, which affects the alignment accuracy and electrical performance of the integrated thick GEM.
By first pre-etching the inner insulating ring to determine the relative position of the inner core board insulating ring and the copper pillar, and then simultaneously controlling the depth of etching the outer copper foil insulating ring and the inner core board insulating ring, the concentricity of the inner and outer insulating rings and the copper pillars is ensured to meet production requirements. This allows for the production of miniaturized and integrated thick GEMs using PCB manufacturing processes.
The concentricity of the inner and outer insulating rings with the copper pillars reached a precision of ±10µm, which improved the alignment accuracy and electrical performance of the integrated thick GEM, optimized the electric field distribution, enhanced the stability of the overall structure, and reduced the risk of electric field distortion and charge accumulation.
Smart Images
Figure CN120897349A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of gas electron multipliers, in particular to an integrated thick GEM and a manufacturing method thereof. BACKGROUND
[0002] The thick GEM, i.e. thick gaseous electron multiplier (THGEM), is a new type of micro-structure gas detector improved from the traditional GEM. The basic structure of the thick GEM detector is that a micro-hole array is made on an insulating plate with a thin conductive metal layer on the upper and lower surfaces. Due to the existence of the micro-hole structure, when a voltage difference is applied to the electrodes on the upper and lower surfaces of the thick GEM detector, a strong electric field can be formed in the micro-hole. When the ionized electrons enter the micro-hole, the avalanche multiplication process of the gas will occur under the action of the strong electric field, so as to realize the amplification of the signal and the detection of the physical process. At present, the thick GEM detector is widely used in the fields of high-energy physics experiments, X-ray, charged particle and neutron detection and imaging.
[0003] The existing thick GEM test module (as shown in Figure 1 ) needs to be combined with a thick GEM plate and a signal readout plate to realize signal detection. Such a combined structure is limited in installation, debugging and special application scenarios. Therefore, in 2010, the industry researchers proposed the idea of an integrated thick GEM structure model (as shown in Figure 2 ). However, how to process a miniaturized and integrated structure model through the process of the PCB has been a difficult problem in the industry. In particular, the concentricity of the copper column and the insulating ring in the structure is required to be very strict during the production process. However, the process schemes tried many times are difficult to meet the precision standard of the concentricity of the insulating ring. Therefore, the insulating ring is prone to eccentricity problem, which may lead to inaccurate signal detection and unstable circuit connection, affecting the alignment accuracy and electrical performance of the integrated thick GEM. SUMMARY
[0004] To overcome the problems in the related art, one of the purposes of the present application is to provide a manufacturing method of an integrated thick GEM. The method determines the relative position of the inner layer core plate insulating ring and the copper column by first performing inner layer insulating ring pre-etching positioning. Then, the outer layer copper foil insulating ring and the inner layer core plate insulating ring are etched synchronously. Since the position of the inner layer core plate insulating ring has been determined, the position of the outer layer copper foil insulating ring can be determined by reference, so that the concentricity of the inner and outer layer insulating rings and the copper column meets the production requirements.
[0005] The manufacturing method of the integrated thick GEM comprises the following steps:
[0006] Two layers of copper foils are laminated to the inner core board through the medium, and copper columns are electroplated in the inner core board;
[0007] A first etching positioning is performed at the insulating ring position of the copper column, and the thickness of the copper foil for the second etching is reserved;
[0008] The outer copper foil is laminated to the inner core board to form an integrated circuit board, and a pad is made by back drilling;
[0009] The outer copper foil insulating ring and the inner core board insulating ring are synchronously etched until the copper column is exposed to complete the second etching.
[0010] For the integrated thick GEM using the PCB process, in the prior art, the outer copper foil insulating ring and the inner core board insulating ring are etched respectively, and the concentricity of the inner and outer insulating rings and the copper column is difficult to meet the production requirements, and the production steps are adjusted several times, but the results are not ideal. The present application first performs a pre-etching of the inner insulating ring, thereby determining the relative position of the inner core board insulating ring and the copper column, and reserving accurate positioning for the second etching of the inner core board insulating ring. The second etching is a synchronous depth-controlled etching of the outer copper foil insulating ring and the inner core board insulating ring. Since the position of the inner core board insulating ring has been determined, the position of the outer copper foil insulating ring can be determined by reference, so that the concentricity of the inner and outer insulating rings and the copper column meets the production requirements, and the processing precision is controlled, so that the inner and outer insulating rings processed meet the accuracy requirement of design size ±10um, and the alignment accuracy and electrical performance of the integrated thick GEM are further ensured.
[0011] In the preferred technical solution of the present application, before the first etching positioning at the insulating ring position of the copper column and reserving the thickness of the copper foil for the second etching, the method further comprises:
[0012] A first etching pattern is designed in the insulating ring area of the copper column of the inner core board, wherein the diameter of the first etching pattern is smaller than the diameter of the final inner core board insulating ring;
[0013] The thickness of the copper foil of the inner core board is measured, the first etching depth is designed to be 26% to 56% of the thickness of the copper foil, and the etching parameters are adjusted according to the first etching depth.
[0014] The diameter of the first etching pattern is smaller than the diameter of the final inner core board insulating ring to balance the side etching effect and ensure that the final insulating ring is within the target size under the influence of side etching. The first etching depth is designed to be 26% to 56% of the thickness of the copper foil to reserve the thickness of the copper foil for the second etching of the inner core board insulating ring. Moreover, since laser is used to make the pad, the reserved copper foil can block the damage of the laser to the substrate and avoid damage to the substrate.
[0015] In the preferred technical solution of the present application, before the second etching is completed, the method further comprises:
[0016] Designing synchronous etching data: measuring the thickness of the outer copper foil, the etching depth of the outer copper foil insulation ring is the thickness of the outer copper foil, designing the diameter of the outer copper foil insulation ring, determining the etching position of the outer copper foil insulation ring, and adjusting the etching parameters according to the thickness of the outer copper foil and the diameter of the insulation ring.
[0017] According to the thickness of the outer copper foil and the diameter of the insulation ring, the etching parameters are determined to ensure that the outer copper foil can be completely etched after synchronous etching. Since the position of the inner core plate insulation ring has been etched for the first time, the remaining copper foil thickness will also be removed in the second synchronous etching.
[0018] In the preferred technical solution of the present application, after the second etching is completed, the method further comprises:
[0019] According to the designed synchronous etching data, the etching position of the outer copper foil insulation ring and the first etching position of the inner core plate insulation ring are synchronously controlled and etched;
[0020] When the etching of the outer copper foil insulation ring is completed, the remaining copper foil of the inner core plate insulation ring is completely etched and the copper column is exposed to complete the second etching.
[0021] During synchronous etching, since the position of the inner core plate insulation ring has been etched for the first time, the second etching can ensure the precise etching position of the inner core plate insulation ring, while controlling the etching depth of the outer copper foil insulation ring and the inner core plate insulation ring. When the etching is completed, the copper column of the inner core plate needs to be exposed; synchronous etching not only saves the process flow, but also improves the alignment accuracy in the integrated thick GEM production process.
[0022] In the preferred technical solution of the present application, before the back drilling is made to make the pad, the method further comprises:
[0023] Designing back drilling data: presetting the blind slot area at the position corresponding to the copper column, designing the back drilling aperture according to the preset blind slot area, designing the back drilling depth according to the thickness of the outer copper foil, the thickness of the dielectric layer and the thickness of the bonding sheet, and ensuring that the remaining dielectric layer thickness after back drilling is 25% to 50% of the overall thickness of the dielectric layer and the bonding sheet between the outer copper foil and the inner core plate.
[0024] The preset back drilling data ensures the structural integrity of the pad made. The remaining part of the dielectric layer is reserved because the instrument used in back drilling may cause damage to the copper foil. The remaining dielectric layer is removed by an instrument that does not damage the copper foil.
[0025] In the preferred technical solution of the present application, the outer layer copper foil and the inner layer core plate are pressed into an integrated circuit board, and the back drilling is used to make the pad, comprising:
[0026] The outer layer copper foil and the inner layer core plate are pressed into an integrated circuit board through a medium layer and an adhesive sheet;
[0027] According to the back drilling data, a blind slot is opened;
[0028] The remaining medium layer is removed by laser to expose the pad position of the inner layer core plate;
[0029] The pad is cleaned by plasma cleaning and ultrasonic cleaning.
[0030] After the laser removes the remaining medium layer, the pad is cleaned by plasma cleaning and ultrasonic cleaning, which not only ensures the cleanliness of the pad, but also facilitates the second etching of the insulation ring and optimizes the welding performance of the integrated thick GEM.
[0031] In the preferred technical solution of the present application, the two layers of copper foil are pressed into an inner layer core plate through a medium layer, and before electroplating the copper column in the inner layer core plate, the method further comprises:
[0032] According to the height of the copper column, the thickness of the medium layer is designed;
[0033] According to the diameter of the copper column, the diameter of the drill hole on the copper foil is designed;
[0034] According to the insulation ring position of the copper column, the first etching pattern is preliminarily designed, and a laser target for controlling concentricity is set in the copper foil.
[0035] By designing the thickness of the medium layer, the diameter of the drill hole and the laser target for controlling concentricity during the manufacturing process of the inner layer core plate, the manufacturing precision of the copper column and the overall alignment of the inner layer core plate are improved, the electrical connection performance is optimized, and the deviation and defects in the production process are reduced.
[0036] In the preferred technical solution of the present application, the two layers of copper foil are pressed into an inner layer core plate through a medium layer, and the copper column is electroplated in the inner layer core plate, comprising:
[0037] The copper foil is cut and the medium layer is cut according to the designed thickness of the medium layer;
[0038] The two layers of copper foil are pressed into an inner layer core plate through a medium layer;
[0039] The inner layer core plate is laser drilled according to the designed drill hole diameter;
[0040] A copper layer is deposited on the hole wall;
[0041] The copper column is electroplated in the hole, and the copper column processing is completed after the hole is filled.
[0042] The two layers of copper foils are precisely pressed with the medium layer to form an inner core plate, and a copper column is plated in the inner core plate, so that an integrated thick GEM high-precision interlayer interconnection structure can be realized.
[0043] In the preferred technical solution of the present application, after the second etching is completed, the method further comprises:
[0044] The solder mask layer of the circuit board is removed, and electrical testing is performed, and after product inspection, the product is packaged and stored.
[0045] The subsequent post-processing steps of removing the solder mask layer, electrical testing and product inspection ensure the quality and reliability of the thick GEM product.
[0046] The second object of the present application is to provide an integrated thick GEM, comprising an inner core plate and an outer copper foil, wherein the inner core plate is provided with a copper column, and the copper column is provided with an inner core plate insulation ring obtained by twice etching, and an outer copper foil insulation ring obtained by etching synchronously with the inner core plate insulation ring during the second etching.
[0047] The inner core plate insulation ring is arranged on the inner core plate, and the outer copper foil insulation ring is arranged on the outer copper foil, and the inner core plate insulation ring is further provided with a solder pad.
[0048] The inner core plate insulation ring, the outer copper foil insulation ring and the copper column are concentric.
[0049] The synchronous etching process of the inner core plate insulation ring and the outer copper foil insulation ring ensures that the concentricity of the two meets the production requirements, improves the electrical performance and reliability of the integrated thick GEM, and secondly, the concentric design of the inner core plate insulation ring, the outer copper foil insulation ring and the copper column not only optimizes the electric field distribution, improves the charge transmission efficiency, but also enhances the stability of the overall structure, effectively reduces the risk of electric field distortion and charge accumulation caused by structural deviation, and realizes the stable production of the small-sized and integrated thick GEM.
[0050] The present application has the following advantages:
[0051] The application provides a manufacturing method of an integrated thick GEM, which comprises the following steps: firstly, pre-etching an inner layer insulating ring to determine the relative position of the inner layer core plate insulating ring and the copper column, and leaving accurate positioning for the second etching of the inner layer core plate insulating ring; and secondly, synchronously controlling the depth etching of the outer layer copper foil insulating ring and the inner layer core plate insulating ring, and determining the relative distance of the outer layer copper foil insulating ring by the position reference of the inner layer core plate insulating ring, so that the concentricity of the inner and outer layer insulating rings and the copper column reaches the production requirement, the processing precision is controlled, the inner and outer layer insulating rings processed reach the accuracy requirement of the design size ±10um, the alignment accuracy and the electrical performance of the integrated thick GEM are further ensured, and the purpose of producing the miniaturized and integrated thick GEM through the process of the PCB is achieved.
[0052] The application also provides an integrated thick GEM produced by the process of the PCB, wherein the synchronous etching process of the inner layer core plate insulating ring and the outer layer copper foil insulating ring ensures that the concentricity of the two reaches the production requirement, and the electrical performance and the reliability of the integrated thick GEM are improved; secondly, the concentric design of the inner layer core plate insulating ring, the outer layer copper foil insulating ring and the copper column not only optimizes the electric field distribution, improves the charge transmission efficiency, but also enhances the stability of the overall structure, effectively reduces the risk of electric field distortion and charge accumulation caused by structural deviation, and realizes the stable production of the miniaturized and integrated thick GEM. BRIEF DESCRIPTION OF DRAWINGS
[0053] Figure 1 It is a physical schematic diagram of a thick GEM test module in the prior art;
[0054] Figure 2 It is a model assumption diagram of an integrated thick GEM proposed in 2010;
[0055] Figure 3 It is a flowchart of the manufacturing method of the integrated thick GEM in the embodiment of the application;
[0056] Figure 4 It is a structural schematic diagram of the integrated thick GEM in the embodiment of the application;
[0057] Figure 5 It is a copper column position schematic diagram of the integrated thick GEM in the embodiment of the application;
[0058] Figure 6 It is a first etching position schematic diagram of the inner layer core plate of the integrated thick GEM in the embodiment of the application;
[0059] Figure 7 It is a pad position schematic diagram of the integrated thick GEM in the embodiment of the application;
[0060] Figure 8 It is an insulating ring position schematic diagram of the integrated thick GEM in the embodiment of the application;
[0061] Figure 9 is a physical schematic diagram of an integrated thick GEM in an embodiment of the present application. DETAILED DESCRIPTION
[0062] The preferred embodiments of the present application will be described in more detail with reference to the drawings. Although the preferred embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present application is more thorough and complete, and the scope of the present application is fully conveyed to those skilled in the art.
[0063] Thick GEM, i.e., thick gaseous electron multiplier (THGEM), is a new type of micro-structured gas detector improved from traditional GEM. The basic structure of the thick GEM detector is that a micro-hole array is made on an insulating plate with a thin conductive metal layer on the upper and lower surfaces. Due to the existence of the micro-hole structure, when a voltage difference is applied to the electrodes on the upper and lower surfaces of the thick GEM detector, a strong electric field can be formed in the micro-hole. When the ionized electrons enter the micro-hole, the avalanche multiplication process of the gas will occur under the action of the strong electric field, thereby realizing the amplification of the signal and the detection of the physical process. At present, the thick GEM detector has been widely used in the fields of high-energy physics experiments, X-ray, charged particle and neutron detection and imaging, etc.
[0064] The existing thick GEM test module (as shown in Figure 1 ) needs to combine both the thick GEM plate and the signal readout plate to realize signal detection. This combined structure is limited in installation, debugging and special application scenarios. Therefore, in 2010, the industry researchers proposed the idea of an integrated thick GEM structure model (as shown in Figure 2 ), but how to process a miniaturized and integrated structure model through the process of PCB has always been a difficult problem in the industry. Especially in the production process, the concentricity of the copper column and its insulating ring in the structure is required to be very strict, but the process scheme tried several times is difficult to meet the precision standard of the concentricity of the insulating ring. Therefore, the insulating ring is prone to eccentricity problem, which may lead to inaccurate signal detection and unstable circuit connection of the finished product, affecting the alignment accuracy and electrical performance of the integrated thick GEM.
[0065] Based on this, the present application provides an integrated thick GEM and a manufacturing method thereof.
[0066] Embodiment 1
[0067] Referring to Figures 3-9 , the manufacturing method of the integrated thick GEM provided in the embodiment includes the following steps:
[0068] According to the copper column height design, the inner core board (such as shown in Figure 4 , Figure 5 ) medium layer thickness, according to the copper column diameter design on the copper foil drilling diameter, according to the copper column insulation ring position preliminary design first etching pattern, in the copper foil set for control concentricity laser target; through the design of medium layer thickness, drilling diameter and make for control concentricity laser target in the inner core board manufacturing process, improve the manufacturing precision of copper column and the overall alignment of inner core board;
[0069] The copper foil is cut and the medium layer is cut according to the designed medium layer thickness, the two copper foils are laminated into the inner core board through the medium layer, the inner core board is laser drilled according to the designed drilling diameter, the copper layer is deposited on the hole wall, the copper column is electroplated in the hole, and the copper column processing is completed after the hole is filled; the two copper foils and the medium layer are precisely laminated to form the inner core board, and the copper column is electroplated therein, which can realize the integrated thick GEM high-precision interlayer interconnection structure;
[0070] The first etching pattern is designed in the insulation ring area of the inner core board copper column, wherein the diameter of the first etching pattern is less than the diameter of the final inner core board insulation ring, the thickness of the inner core board copper foil is measured, the first etching depth is designed to be 26% to 56% of the thickness of the copper foil, and the etching parameters are adjusted according to the first etching depth, as shown in Figure 6 , the first etching positioning is carried out at the insulation ring position of the copper column, and the thickness of the copper foil for the second etching is reserved, wherein the optimal reserved copper foil thickness is 50% of the thickness of the copper foil; the diameter of the first etching pattern is less than the diameter of the final inner core board insulation ring to balance the side etching effect and ensure that the final obtained insulation ring is within the target size under the influence of side etching; the first etching depth is designed to be 26% to 56% of the thickness of the copper foil to reserve the copper foil thickness for the second etching of the inner core board insulation ring, and because laser is used in subsequent manufacturing of the pad, the reserved copper foil can block the damage of laser to the substrate, avoiding damage to the substrate;
[0071] Design back drilling data: preset blind groove area at the corresponding position of the copper column, design back drilling aperture according to the preset blind groove area, design back drilling depth according to the thickness of the outer copper foil, the thickness of the medium layer and the thickness of the bonding sheet, and ensure that the remaining medium layer thickness after back drilling is 25% to 50% of the overall thickness of the medium layer and the bonding sheet between the outer copper foil and the inner core board; preset back drilling data to ensure the structural integrity of the manufactured pad, and the reserved part of the medium layer is because the instrument used in back drilling may cause damage to the copper foil, and the remaining medium layer is removed by an instrument that will not damage the copper foil;
[0072] The outer layer copper foil and the inner layer core plate are compressed into an integrated circuit board through a medium layer and an adhesive sheet, a blind slot is opened according to the designed back drilling data, the remaining medium layer is removed by laser to expose the pad position (as shown in Figure 7 The pad is cleaned by plasma cleaning and ultrasonic cleaning after the remaining medium layer is removed by laser, which ensures the cleanliness of the pad and facilitates the second etching of the insulating ring.
[0073] The thickness of the outer layer copper foil is measured, the etching depth of the outer layer copper foil insulating ring is the thickness of the outer layer copper foil, the diameter of the outer layer copper foil insulating ring is designed, the etching position of the outer layer copper foil insulating ring is determined, and the etching parameters are adjusted according to the thickness of the outer layer copper foil and the diameter of the outer layer copper foil insulating ring; the etching parameters are determined according to the thickness of the outer layer copper foil and the diameter of the insulating ring, so that the outer layer copper foil can be completely etched after synchronous etching, and since the insulating ring position of the inner layer core plate has been etched for the first time, the remaining copper foil thickness will also be removed in the second synchronous etching.
[0074] As shown in Figure 8 , the outer layer copper foil insulating ring etching position and the inner layer core plate insulating ring first etching position are synchronously controlled and etched according to the designed synchronous etching data, when the outer layer copper foil insulating ring completes etching, the remaining copper foil of the inner layer core plate insulating ring is completely etched and the copper pillar is exposed to complete the second etching; since the inner layer core plate insulating ring position has been fixed after the first etching, the second etching can ensure the accuracy of the inner layer core plate insulating ring etching position, and the etching depth of the outer layer copper foil insulating ring and the inner layer core plate insulating ring is controlled, and the copper pillar of the inner layer core plate needs to be exposed when etching is completed; synchronous etching not only saves the process flow, but also improves the alignment accuracy in the integrated thick GEM production process;
[0075] Optionally, after the insulating ring is completed, a post-processing step is further included, the post-processing step includes removing the circuit board solder mask layer and performing electrical testing, and after completing the finished product inspection, the product is packaged and stored; the post-processing step ensures the quality and reliability of the integrated thick GEM product.
[0076] The present application first etches the inner layer insulating ring to determine the relative position of the inner layer core plate insulating ring and the copper pillar, leaving a precise position for the second etching of the inner layer core plate insulating ring; the outer layer copper foil insulating ring and the inner layer core plate insulating ring are synchronously controlled and etched in the second etching, the outer layer copper foil insulating ring determines the relative distance by referring to the position of the inner layer core plate insulating ring, so that the concentricity of the inner and outer layer insulating rings and the copper pillar meets the production requirements, and the processing precision is controlled, so that the inner and outer layer insulating rings processed meet the accuracy requirement of design size ± 10 um, further ensuring the alignment accuracy and electrical performance of the integrated thick GEM, so as to realize the purpose of producing small and integrated thick GEM through the process of PCB.
[0077] Example 2
[0078] See Figures 3-9 The method for fabricating an integrated thick GEM provided in this embodiment includes the following steps:
[0079] The inner core board is designed according to the height of the copper pillar (e.g., Figure 4 The dielectric layer thickness (as shown) is determined by designing the drill hole diameter on the copper foil based on the diameter of the copper pillar. In this embodiment, the dielectric layer thickness is 0.1 mm.
[0080] The initial etching pattern is designed based on the position of the insulating ring of the copper pillar, and a laser target is set inside the copper foil to control concentricity.
[0081] The copper foil is cut into pieces, and the dielectric layer is cut into pieces according to the designed dielectric layer thickness. The two copper foils are then pressed together to form the inner core board through the dielectric layer.
[0082] Laser drilling is performed on the inner core board according to the designed drilling diameter. A copper layer is deposited on the hole wall, and copper pillars are electroplated inside the hole. After filling the hole, the copper pillar processing is completed.
[0083] The first etching pattern is designed in the insulating ring area of the inner core board copper pillar, wherein the diameter of the first etching pattern is smaller than the final inner core board insulating ring diameter; in this embodiment, the diameter of the first etched insulating ring is 50um-75um smaller than the final inner core board insulating ring diameter to reduce the dimensional changes caused by the side etching effect.
[0084] Measure the thickness of the inner core board copper foil, design the first etching depth to be 26% to 56% of the copper foil thickness, and adjust the etching parameters according to the first etching depth;
[0085] The first etching is performed at the insulating ring position of the copper pillar to position it, leaving room for the copper foil thickness of the second etching. In this embodiment, the copper foil thickness is about 34um, and the reserved copper foil thickness is the optimal parameter of 17um. The first etching pattern will be completely preserved to achieve the positioning effect, reducing the risk of pattern manufacturing deviation and insulation ring eccentricity.
[0086] Dry film is applied to both sides of the inner core board and the inner layer pattern is transferred. The inner layer acid etching is performed and the dry film is removed to obtain the inner layer circuit pattern.
[0087] The inner core board is browned to clean and roughen the surface of the copper foil.
[0088] Two layers of copper foil are cut into pieces, and the inner layer circuit patterns are made separately. After etching and inspection, browning treatment is performed, and then they are waited to be pressed together with the inner layer core board.
[0089] The two outer copper foil layers and the inner core board are pressed together into an integral circuit board through a dielectric layer and an adhesive sheet.
[0090] The plug hole is made (as shown in Figure 9 A copper layer is deposited on the hole wall, and the outer layer copper foil and the copper layer on the hole wall are thickened. In this embodiment, the step of electroplating copper is realized by using a VCP (Vertical Continuous Plating) process;
[0091] The double-sided dry film is pasted on the circuit board, and the outer layer pattern is transferred. The outer layer is etched with acid, and the dry film is removed to obtain a complete circuit pattern. The solder resist layer is coated on the surface of the circuit board;
[0092] Design back drilling data: preset blind groove area at the position corresponding to the copper column, design back drilling aperture according to the preset blind groove area, design back drilling depth according to the thickness of the outer layer copper foil, the thickness of the dielectric layer and the thickness of the adhesive sheet, and ensure that the remaining dielectric layer thickness after back drilling is 25% to 50% of the overall thickness of the dielectric layer and the adhesive sheet between the outer layer copper foil and the inner layer core board. In this embodiment, the overall thickness of the dielectric layer and the adhesive sheet between the outer layer copper foil and the inner layer core board is about 0.4mm, and the remaining dielectric layer thickness required for back drilling is about 0.1mm to 0.2mm. The remaining dielectric layer is removed by using an instrument that does not damage the copper foil because the instrument used for back drilling may cause damage to the copper foil;
[0093] According to the designed back drilling data, a blind groove is opened, and the remaining dielectric layer is removed by laser to expose the position of the solder pad of the inner layer core board. The solder pad is cleaned by plasma cleaning and ultrasonic cleaning. After the remaining dielectric layer is removed by laser, the solder pad is cleaned by plasma degreasing and ultrasonic cleaning, which not only ensures the cleanliness of the solder pad, but also facilitates the second etching of the insulating ring;
[0094] Design synchronous etching data: measure the thickness of the outer layer copper foil, the etching depth of the outer layer copper foil insulating ring is the thickness of the outer layer copper foil, design the diameter of the outer layer copper foil insulating ring, determine the etching position of the outer layer copper foil insulating ring, and adjust the etching parameters according to the thickness of the outer layer copper foil and the diameter of the outer layer copper foil insulating ring; determine the etching parameters according to the thickness of the outer layer copper foil and the diameter of the insulating ring, and ensure that the outer layer copper foil can be completely etched after synchronous etching. Since the position of the insulating ring of the inner layer core board has been etched once, the remaining copper foil thickness will also be removed in the second synchronous etching;
[0095] According to the synchronous etching data of the design, the etching position of the outer copper foil insulating ring and the first etching position of the inner core plate insulating ring are synchronously controlled and etched, when the outer copper foil insulating ring is completed, the remaining copper foil of the inner core plate insulating ring is completely etched and the copper column is exposed to complete the second etching; during the synchronous etching, since the position of the inner core plate insulating ring is fixed after the first etching, the second etching can ensure the etching position of the inner core plate insulating ring to be accurate, and the etching depth of the outer copper foil insulating ring and the inner core plate insulating ring is controlled, and when the etching is completed, the copper column of the inner core plate needs to be exposed; the synchronous etching saves the process flow and improves the alignment accuracy in the integrated thick GEM production process.
[0096] Optionally, after the insulating ring is completed, a post-processing step is further included, the post-processing step includes removing the circuit board solder mask layer and performing electrical testing, and after the finished product inspection is completed, the integrated thick GEM product is packaged and stored, and the like, in the embodiment, a physical schematic diagram of the integrated thick GEM finished product is as shown in Figure 9 .
[0097] The present application first pre-etches the inner insulating ring to determine the relative position of the inner core plate insulating ring and the copper column, and leaves accurate positioning for the second etching of the inner core plate insulating ring; during the second etching, the outer copper foil insulating ring and the inner core plate insulating ring are synchronously controlled and etched, the outer copper foil insulating ring determines the relative distance by referring to the position of the inner core plate insulating ring, the concentricity of the inner and outer insulating rings and the copper column reaches the production requirement, the processing precision is controlled, the inner and outer insulating rings processed reach the accuracy requirement of design size ± 10 um, the alignment accuracy and electrical performance of the integrated thick GEM are further ensured, and the purpose of producing the miniaturized and integrated thick GEM through the process of the PCB is achieved.
[0098] Embodiment 3
[0099] Referring to Figures 2-9 , the integrated thick GEM provided by the embodiment includes Figure 2 four layers of signal layers formed by four layers of copper foils respectively, and a medium layer between adjacent copper foils, wherein the inner core plate formed by the second layer of copper foil and the third layer of copper foil is provided with a copper column (micro hole) with a diameter of 0.1 mm, the copper column is provided with an inner core plate insulating ring obtained by twice etching, and an outer copper foil insulating ring obtained by synchronously etching with the second etching of the inner core plate insulating ring, the inner core plate insulating ring is arranged on the inner core plate, the outer copper foil insulating ring is arranged on the outer copper foil, and the inner core plate insulating ring is further provided with a solder pad;
[0100] The inner core plate insulating ring, the outer copper foil insulating ring and the copper column are concentric.
[0101] In the embodiment, the maximum diameter of the inner core plate insulation ring is 0.3 mm, and the maximum diameter of the outer copper foil insulation ring is 0.7 mm, wherein the pad size on the inner core plate insulation ring is about 0.5 mm.
[0102] The integrated thick GEM provided by the application is produced by adopting the process of the PCB, wherein the synchronous etching process of the inner core plate insulation ring and the outer copper foil insulation ring ensures that the concentricity of the two meets the production requirements, and improves the electrical performance and reliability of the integrated thick GEM; secondly, the concentric design of the inner core plate insulation ring, the outer copper foil insulation ring and the copper column not only optimizes the electric field distribution, improves the charge transmission efficiency, but also enhances the stability of the overall structure, effectively reduces the risk of electric field distortion and charge accumulation caused by structural deviation, and realizes the stable production of the small-sized and integrated thick GEM.
[0103] For the convenience of description, spatial relative terms such as "above", "upper", "top surface", "upper" and the like can be used herein to describe the spatial positional relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawing is inverted, the device described as "above" or "above" other devices or structures will be positioned "below" or "below" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.
[0104] In addition, it should be noted that the use of the terms "first", "second" and the like to qualify parts is only for the convenience of distinguishing the corresponding parts, and the above terms have no special meaning unless otherwise stated, and therefore cannot be understood as limiting the scope of protection of the present application.
[0105] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A method for fabricating an integrated thick GEM, characterized in that: Includes the following steps: Two layers of copper foil are laminated together with a dielectric layer to form an inner core board, and copper pillars are electroplated inside the inner core board. The first etching is performed at the insulating ring position of the copper pillar to position it, leaving room for the thickness of the copper foil for the second etching. The outer copper foil and the inner core board are pressed together to form an integral circuit board, and the solder pads are made by back drilling. The outer copper foil insulating ring and the inner core board insulating ring are simultaneously etched until the copper pillars are exposed, thus completing the second etching.
2. The method for fabricating an integrated thick GEM according to claim 1, characterized in that: Before performing the first etching positioning at the insulating ring position of the copper pillar, and before reserving the thickness for the second etching of the copper foil, the method further includes: The first etch pattern is designed in the insulating ring area of the inner core board copper pillar, where the diameter of the first etch pattern is smaller than the final diameter of the inner core board insulating ring. Measure the thickness of the inner core board copper foil, design the first etching depth to be 26% to 56% of the copper foil thickness, and adjust the etching parameters according to the first etching depth.
3. The method for fabricating an integrated thick GEM according to claim 1, characterized in that: Before the simultaneous etching of the outer copper foil insulating ring and the inner core board insulating ring until the copper pillars are exposed to complete the second etching, the method further includes: Design synchronous etching data: Measure the thickness of the outer copper foil, the etching depth of the outer copper foil insulating ring is the thickness of the outer copper foil, design the diameter of the outer copper foil insulating ring, determine the etching position of the outer copper foil insulating ring, and adjust the etching parameters according to the thickness of the outer copper foil and the diameter of the outer copper foil insulating ring.
4. The method for fabricating an integrated thick GEM according to claim 3, characterized in that: The simultaneous etching of the outer copper foil insulating ring and the inner core board insulating ring until the copper pillars are exposed completes the second etching process, including: Based on the designed synchronous etching data, synchronous depth-controlled etching was performed on the etching positions of the outer copper foil insulating ring and the first etching position of the inner core board insulating ring. When the outer copper foil insulating ring is etched, ensure that the remaining copper foil of the inner core board insulating ring is completely etched and the copper pillar is exposed in order to complete the second etching.
5. The method for fabricating an integrated thick GEM according to claim 1, characterized in that: Before laminating the outer copper foil and the inner core board into a complete circuit board and creating the solder pads using back drilling, the method further includes: Design back-drilling data: Pre-set the blind slot area at the corresponding position of the copper pillar, design the back-drilling hole diameter according to the pre-set blind slot area, and design the back-drilling depth according to the thickness of the outer copper foil, the dielectric layer, and the adhesive sheet, ensuring that the remaining dielectric layer thickness after back-drilling is 25% to 50% of the overall thickness of the dielectric layer and adhesive sheet between the outer copper foil and the inner core board.
6. The method for fabricating an integrated thick GEM according to claim 5, characterized in that: The process of laminating the outer copper foil and the inner core board into a complete circuit board, and back-drilling to create solder pads, includes: The outer copper foil and the inner core board are laminated together into an integral circuit board through a dielectric layer and an adhesive sheet; Drill blind slots according to the back-drill data of the design; The remaining dielectric layer is removed by laser to expose the pads of the inner core board; The pads are subjected to plasma cleaning and ultrasonic cleaning.
7. The method for fabricating an integrated thick GEM according to claim 1, characterized in that: The method further includes, before electroplating copper pillars into the inner core board by laminating two layers of copper foil together with a dielectric layer, the process of which involves: The thickness of the dielectric layer is designed based on the height of the copper pillar; The diameter of the drill hole on the copper foil is designed based on the diameter of the copper pillar. The initial etching pattern is designed based on the position of the insulating ring of the copper pillar, and a laser target is set inside the copper foil to control concentricity.
8. The method for fabricating an integrated thick GEM according to claim 7, characterized in that: The process of laminating two layers of copper foil into an inner core board using a dielectric layer, and electroplating copper pillars within the inner core board, includes: Cut the copper foil and cut the dielectric layer according to the designed dielectric layer thickness; Two layers of copper foil are laminated together using a dielectric layer to form an inner core board; Laser drilling is performed on the inner core board according to the designed drilling diameter; A copper layer is deposited on the hole wall; The copper pillar is electroplated inside the hole, and the hole is filled to complete the copper pillar processing.
9. The method for fabricating an integrated thick GEM according to claim 1, characterized in that: After the simultaneous etching of the outer copper foil insulating ring and the inner core board insulating ring until the copper pillars are exposed to complete the second etching, the method further includes: Remove the solder mask from the circuit board and perform electrical tests. After completing the finished product inspection, package and store the product.
10. An integrated thick GEM, characterized by: It includes an inner core board and an outer copper foil. The inner core board is provided with a copper pillar. The copper pillar is provided with an inner core board insulating ring obtained by two etching processes and an outer copper foil insulating ring obtained by etching simultaneously with the second etching of the inner core board insulating ring. The inner core board insulating ring is disposed on the inner core board, the outer copper foil insulating ring is disposed on the outer copper foil, and the inner core board insulating ring is also provided with solder pads; The inner core board insulating ring, the outer copper foil insulating ring, and the copper pillar are concentric.