An ultra-long microwave printed circuit board with welding holes at the bottom of a blind slot and its manufacturing process

Abstract

The present application provides an ultra-long microwave printed circuit board with welding holes at the bottom of the blind groove and its manufacturing process. When the early engineering documents are produced, the engineering documents can be spliced ​​and produced in sections, and the large-size files can be split into section files. Positioning holes are set in each section, and the sections are machined. The production steps include protection before welding hole lamination, graded production of target and positioning hole displacement, and local etching of welding holes after blind hole formation. The present application solves the size limitation problem of exposure machine, drilling machine and milling machine; the positioning hole is graded and dislocated to distinguish the production, and each positioning layer and non-positioning layer are separately identified, which solves the target ghosting caused by expansion and contraction and the further misalignment and deviation of blind grooves and blind holes, and avoids scrap caused by misalignment of slots and holes between layers; the inner layer blind hole is locally nickel-gold treated to make an anti-corrosion layer, and alkaline etching is used after the slot is opened, which can solve the problem of copper plating stratification and uneven thickness of blind hole welding holes and ensure the quality of welding holes.

Description

Technical Field

[0001] The invention relates to the technical field of multi-layer microwave printed boards, in particular to an ultra-long microwave printed board with welding holes at the bottom of a blind groove and a manufacturing process thereof. Background Art

[0002] Multilayer microwave printed circuit boards with stepped blind grooves and metal circuit patterns on the bottom are typically manufactured using a no-flow or low-flow adhesive sheet for lamination. The outer core board is typically produced using a full-window or semi-window lamination process before lamination. The exposed portions of the inner core board containing metal circuits require pre-protection with a protective film or adhesive. After lamination and production of the outer circuit layer, a milling machine is used to remove the protective film or adhesive from the circuit layer, ultimately yielding the desired printed circuit board.

[0003] When microwave printed circuit boards are extremely long (800mm or greater), some manufacturing processes cannot be performed due to the size limitations of photolithography or machining equipment. Furthermore, due to the significant cumulative expansion and contraction of the slot positions caused by the manufacturing process, interlayer misalignment is severe. Using a semi-open or fully open window process before lamination can easily lead to inaccurate secondary blind slot openings and misalignment between the blind slot and soldering hole positions, resulting in scrap. This is especially true when the slots have multiple levels, which requires a multi-stage lamination process. The expansion and contraction of different layers are inconsistent, making misalignment particularly severe. Furthermore, when solder holes are contained within stepped blind slots, excess adhesive from the adhesive sheet can flow into the holes during lamination, making cleaning difficult after the cover is removed. Furthermore, solder holes are subjected to two copper plating treatments, which can easily lead to separation of the copper plating layer from the hole wall and uneven plating thickness. Summary of the Invention

[0004] In response to the above-mentioned deficiencies and defects of the existing technology, the present application provides an ultra-long microwave printed circuit board with a welding hole at the bottom of the blind slot and its manufacturing process, which effectively solves the problem of center offset of the slot hole of the ultra-long board, as well as the problem of difficult to remove glue blockage in the welding slot hole or uneven stratification of the hole wall plating.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a manufacturing process for an ultra-long microwave printed circuit board having a welding hole at the bottom of a blind slot, comprising:

[0007] 1) Split the large-size project file into left and right partition project files, set positioning holes in each partition, and perform machining in the partition.

[0008] 2) Produce the first core board, which includes L1 and L2 layers. According to the left and right partitions, produce 1-2 layers of metalized blind holes, L2 layer patterns and primary positioning targets of the first core board, and partially nickel-gold-plated in and around the blind holes of the L2 layer pattern and apply a protective film.

[0009] 3) Make a second core board, which includes L3 layer and L4 layer. Make the L3 layer pattern of the second core board according to the left and right partitions. The data of the L3 layer pattern is adjusted according to the expansion and contraction data after the first core board is made, and the L3 layer target pattern is made in a staggered manner from the L2 layer.

[0010] 4) The first core board and the second chip are laminated for the first time to form a first-level laminate. According to the left and right partitions, the first-level laminate 1-4 layers of metalized blind holes, L4 layer graphics and first-level positioning targets are produced. The L4 layer first-level positioning target does not overlap with the L2 layer primary positioning target and L3 layer target graphics. The blind holes in and around the L4 layer graphics are partially gold-plated and covered with a protective film.

[0011] 5) Make the third core board, which includes L5 and L6 layers. The L5 layer pattern of the third core board is made according to the left and right partitions. The L5 layer pattern data is adjusted according to the expansion and contraction data after the first-level pressing board is made, and the L5 layer target pattern is made in a staggered manner from the target of the positioning layer including the L2 and L4 layers.

[0012] 6) The primary laminate and the third chip are laminated for a second time to form a secondary laminate, and through holes of layers 1 to 6 and patterns of layers L1 and L6 of the secondary laminate are produced according to the left and right partitions.

[0013] 7) Position holes in each layer, open windows to expose the bottom metallized through-holes, and perform local etching.

[0014] Preferably, LDI exposure equipment is used to perform two-part exposure operations according to the left and right partition positioning holes, and a complete circuit pattern is spliced ​​out; drilling and milling machine equipment is used to perform two-part drilling and contour operations according to the left and right partition positioning holes, and a complete machining pattern is spliced ​​out.

[0015] Preferably, the specific steps of step 2) are as follows:

[0016] 2-1) Drill primary positioning holes, rivet holes, and 1-2 layers of blind holes in the left partition of the first core plate according to the left and right partitions, and make primary positioning holes, rivet holes, and 1-2 layers of blind holes in the right partition according to the right end positioning holes of the left partition;

[0017] 2-2) Copper plating inside the hole;

[0018] 2-3) Apply dry film, measure the expansion and contraction data of the positioning holes in the X and Y directions, and adjust the film data according to the expansion and contraction values. According to the left and right partitions, produce the L2 layer pattern and the primary positioning target pattern on this layer;

[0019] 2-4) The L2 layer pattern is located in and around the blind vias in layers 1-2 and needs to be grooved to expose the exposed parts and perform local nickel-gold plating on the surface;

[0020] 2-5) The exposed parts around the blind holes in the 1-2 layers need to be grooved and locally protected with a high-temperature resistant protective film.

[0021] More preferably, the protective film should withstand temperatures higher than the lamination temperature, typically 230°C for at least six hours without deterioration. The protective film is laser milled and aligned with the center of the blind holes in the first core board's first or second layers. Thermal rapid pressing or roller pressing is used to ensure a tight bond between the high-temperature resistant film and the first core board, ensuring it withstands corrosion from solutions during the manufacturing process.

[0022] Preferably, the specific steps of step 3) are as follows:

[0023] 3-1) Drill positioning holes and rivet holes for the left and right partitions of the second core plate according to the data after the expansion and contraction of the first core plate, and align them with the rivet holes after the expansion and contraction of the first core plate;

[0024] 3-2) Apply dry film, and make L3 layer pattern according to the left and right partitions and the adjusted expansion and contraction data. The target pattern of L3 layer is offset and distinguished from that of L2 layer.

[0025] Preferably, the specific steps of step 4) are as follows:

[0026] 4-1) Browning / blackening the first and second core boards; preparing the first lamination bonding sheet, and using laser milling to open windows at the blind slot positions corresponding to the blind holes in the first and second layers, and performing the first lamination to form a first-level laminate;

[0027] 4-2) Perform X-ray drilling according to the L2 layer primary positioning target pattern to form the primary positioning hole, and measure its expansion and contraction data to align the L2 layer pattern, primary positioning target pattern, and primary positioning hole of each individual plate;

[0028] 4-3) According to the left and right partitions, drill the first-level rivet holes and blind holes on the 1st to 4th layers of the left partition and the first-level rivet holes and blind holes on the 1st to 4th layers of the right partition according to the first-level positioning holes;

[0029] 4-4) Copper plating inside the hole;

[0030] 4-5) Create the L4 layer pattern using the same steps as the L2 layer. The first-level target pattern contained in the L4 layer pattern does not overlap with the target patterns of the L2 and L3 layers, so they are created separately.

[0031] 4-6) The L4 layer pattern is located in and around the 1-4 blind holes, and the exposed parts need to be grooved, partially gold-plated, and covered with a protective film.

[0032] Preferably, the specific steps of step 5) are as follows:

[0033] 5-1) Drill positioning holes and rivet holes for the left and right partitions of the third core plate according to the adjusted expansion and contraction data, and align them with the rivet holes of the first-level press plate;

[0034] 5-2) Apply dry film, and make L5 layer graphics according to the left and right partitions and the adjusted expansion and contraction data. The target graphics of L5 layer are offset and distinguished from the targets of the positioning layers (including L2 and L4 layers).

[0035] Preferably, the specific steps of step 6) are as follows:

[0036] 6-1) The primary laminate and the third core sheet are browned / blackened, and the bonding sheet for the second lamination is prepared. The blind slot positions corresponding to the blind holes in the 1st to 4th layers are laser milled, and the second lamination is performed to form the secondary laminate;

[0037] 6-2) Perform X-ray drilling on the target according to the L4 layer primary target pattern to form secondary positioning holes, and measure their expansion and contraction data. Drill the primary positioning holes for later blind slot positioning, so that the L2 layer pattern and the primary positioning holes are aligned, and the L4 layer pattern and the secondary positioning holes are aligned;

[0038] 6-3) According to the left and right partitions, drill the left partition through holes and the right partition through holes according to the secondary positioning holes;

[0039] 6-4) Copper plating inside the hole;

[0040] 6-5) Apply dry film and make L1 and L6 patterns according to the left and right partitions;

[0041] 6-6) The entire board is nickel-gold plated.

[0042] Preferably, the specific step requirements of step 7) are as follows:

[0043] 7-1) Use the first-level positioning holes for positioning, divided into left and right areas, and open windows at the positions of the 1-2 layer welding metallization holes to expose the protective film, ensuring that the center of the window position is aligned with the center of the L2 layer pattern welding hole position;

[0044] 7-2) Use the secondary positioning holes for positioning, divided into left and right areas, to open windows at the locations of the 1-4 layers of soldering metallization holes to expose the protective film, ensuring that the center of the window position is aligned with the center of the L4 layer pattern soldering hole position;

[0045] 7-3) Remove the protective film and residual glue at the bottom of the blind groove to expose the metallized hole pattern pad;

[0046] 7-4) Apply dry film to protect other locations except the blind groove, and perform alkaline etching to remove the unreliable copper plating layer after the secondary copper plating in the blind hole.

[0047] The present invention also provides an ultra-long microwave printed circuit board with a welding hole at the bottom of the blind groove, which is manufactured by the above manufacturing process.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. For large sizes, using partitioning to create files and then splicing them together can completely solve the size limitations of LDI exposure machines, drilling machines, and milling machines, and avoid the inability to produce some graphic machining processes due to size limitations.

[0050] 2. When the graphics have accumulated large expansion and contraction and the individual differences are large, the positioning holes are graded and dislocated to distinguish the production. Each positioning layer and non-positioning layer can be identified separately. This can completely solve the target ghosting caused by expansion and contraction and the further misalignment of blind slots and blind holes, and avoid scrap caused by misalignment of slots and holes between layers.

[0051] 3. After the inner blind hole, local nickel-gold treatment is used to make an anti-corrosion layer. After the slotted hole is opened, alkaline etching is used to etch away unreliable and unqualified secondary copper plating. This can solve the problems of copper plating delamination and uneven thickness of blind hole welding holes and ensure the quality of welding holes. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of the engineering file partitioning production of the present invention.

[0053] Figure 2 It is a schematic diagram of the production process of the present invention.

[0054] Figure 3 This is a schematic diagram of the staggered and graded production of positioning holes and targets according to the present invention, wherein:

[0055] Position 0: Primary positioning hole, the first positioning hole drilled on each core board, used for drilling rivet holes and 1-2 blind holes for positioning;

[0056] Position 1: Primary positioning target, produced on the same layer as the L2 layer pattern, used for X-ray positioning and drilling of first-level positioning holes after one-time lamination, and used for blind slot positioning in layers 3-6;

[0057] Position 2: It is the first-level positioning target, which is made on the same layer as the L4 layer pattern. After the second lamination, it is used for X-ray positioning and drilling of second-level positioning holes. It is used for positioning blind slot holes in the 5-6 layers.

[0058] X-position: This is a non-positioning layer target, manufactured on the same layer as L3 and L5, and is used for layers where positioning accuracy is not critical. Subsequent pattern etching is performed using conventional processes. DETAILED DESCRIPTION

[0059] In order to more clearly illustrate the present invention, the present invention is further described in detail below in conjunction with embodiments and with reference to the accompanying drawings. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0060] Example

[0061] For ease of description, the technical solution described in this application is illustrated using a six-layer board with ultra-long, multi-stage blind slots as an example. The example product contains plated holes for soldering on layers 1-2, with non-plated blind slots corresponding to layers 3-6; it also contains plated holes for soldering on layers 1-4, with non-plated blind slots corresponding to layers 5-6. The processing steps and precautions are as follows:

[0062] 1. Partitioning graphics and partitioning machining technology

[0063] Due to the extra-long size of the printed circuit board, the drilling, imaging, and shape production may exceed the size limit of the equipment, and the cumulative expansion and contraction is too large, which can easily cause misalignment of the hole pattern and the hole slot. When the early engineering files are produced, the engineering files can be spliced ​​and produced in sections, and the large-size files can be split into section files. Positioning holes are set in each section, and machining is performed in sections. See the attached Figure 1 In this embodiment, the entire large-scale project file is split into two sets of project files, the left partition and the right partition. The positioning holes of the left partition project file are A, B, C, D, and the positioning holes of the right partition project file are C, D, E, F.

[0064] It should be noted that due to the different core board materials and board thicknesses, expansion and contraction compensation should be given to the drilling and graphic engineering files based on the material, board thickness, process flow and empirical data.

[0065] Second, the production steps include protection of welding holes before lamination, staggered and graded production of targets and positioning holes, and local etching of welding holes after blind hole formation, such as Figure 2 shown.

[0066] 1. Make the first core board and the L2 layer pattern of the first core board, and apply protective film to some parts. The specific steps are as follows:

[0067] 1) Cutting and drilling: According to the left and right partitions, drill the primary positioning holes, rivet holes and 1-2 layers of blind holes in the left partition of the first core board respectively, and according to the positioning holes on the right end of the left partition ( Figure 1 C, D holes), make the right partition primary positioning holes, rivet holes and 1-2 layers of blind holes.

[0068] 2) Hole plating: According to the conventional microwave board hole metallization process, copper plating is completed in the hole.

[0069] 3) Graphics: Paste the dry film, measure the expansion and contraction data of the positioning holes in the X and Y directions, and adjust the film data according to the expansion and contraction values. According to the left and right partitions, make the L2 layer graphics, including the primary positioning target graphics.

[0070] For ease of description, the layer with circuit patterns corresponding to the slot positions is defined as the positioning layer, and the layer containing only shielding patterns or support patterns and no precise positioning requirements for the slot positions are defined as the non-positioning layer. Therefore, the L2 layer is the positioning layer, and the corresponding positioning target is the primary positioning target, and both are produced simultaneously. It is recommended to use LDI exposure equipment to produce the left and right partition patterns. The two partitions are exposed according to the left and right partition positioning holes respectively, and the complete pattern is spliced ​​together. Note that the intersection of the left and right partitions is aligned, and there should be no exposure seams. Subsequent pattern etching production is carried out according to conventional processes.

[0071] 4) Local nickel-gold plating: The blind holes in and around the L2 layer graphics 1-2 need to be grooved and exposed, and local nickel-gold plating is performed on the surface.

[0072] 5) Partially apply a protective film: Slots should be cut around the blind holes in the first and second layers, exposing exposed areas. This area should be protected with a high-temperature-resistant protective film. The protective film should withstand temperatures higher than the lamination temperature, typically 230°C for at least six hours without deterioration. The protective film is laser milled and aligned with the centers of the blind holes in the first and second layers of the first core board. Hot pressing or roller pressing is used to securely bond the high-temperature-resistant film to the first core board, ensuring it withstands corrosion from the solutions used during the manufacturing process.

[0073] 2. Make the second core board and the L3 layer pattern of the second core board. Note that the drilling data and L3 layer pattern data should be adjusted according to the expansion and contraction data after the first core board is made. The specific steps are as follows:

[0074] 1) Cutting and drilling: According to the left and right partitions, drill the left and right partition positioning holes and rivet holes of the second core plate respectively according to the data after the expansion and contraction of the first core plate, and align them with the rivet holes after the expansion and contraction of the first core plate to prevent the two from misalignment when riveting.

[0075] 2) Graphics: Stick the dry film, and make the L3 layer graphics according to the left and right partitions and the data after adjusting the expansion and contraction. Because the L3 layer is a non-positioning layer, in order to prevent the L2 layer and L3 layer from expanding and contracting inconsistently after pressing, causing the target graphics to be offset and ghosted after pressing, affecting the alignment of the drilling target and the blind groove, the target graphics of the L3 layer are made separately from the L2 layer. Figure 3 shown.

[0076] 3. Make a first-level laminate and produce the L4 layer pattern of the first-level laminate. The specific steps are as follows:

[0077] 1) Lamination: The first and second core boards are browned / blackened; the first lamination bonding sheet is prepared, and the blind slot positions corresponding to the blind holes in the 1-2 layers are opened by laser milling; the first lamination is performed according to the bonding sheet lamination process requirements to form a first-level laminate.

[0078] 2) Target Drilling: X-ray drilling is performed according to the L2 primary target pattern to form primary positioning holes and measure their expansion and contraction data. Due to the large size of each panel, the expansion and contraction after pressing may vary slightly, and the expansion and contraction data are averaged. However, the L2 layer pattern, primary target pattern, and primary positioning holes of each individual panel are guaranteed to be aligned, forming a unified positioning system.

[0079] 3) Drilling blind holes on the 1-4th layer: According to the left and right partitions, drill the first-level rivet holes and blind holes on the 1-4th layer in the left partition and the first-level rivet holes and blind holes on the 1-4th layer in the right partition according to the first-level positioning holes.

[0080] 4) Hole plating: According to the conventional microwave board hole metallization process, complete the copper plating in the hole.

[0081] 5) Graphics: The steps for making L4 layer graphics are the same as those for L2 layer, but the L4 layer graphics contain the first level target graphics. The first level target graphics do not overlap with the previous target graphics, so they are made separately. Figure 3 shown.

[0082] 6) Partial gold plating and partial protective film application: The L4 layer pattern located in and around the 1-4 blind vias requires slotting to expose the exposed portion for partial gold plating. The protective film application steps are the same as for the L2 layer pattern.

[0083] 4. Make the third core board and the L5 layer pattern of the third core board. Note that the drilling data and L5 layer pattern data should be adjusted according to the expansion and contraction data after the first-level press board is made. The specific steps are as follows:

[0084] 1) Cutting and drilling: According to the left and right partitions, drill the left and right partition positioning holes and rivet holes of the third core plate respectively according to the adjusted expansion and contraction data, and align them with the rivet holes of the first-level press plate to prevent the two from misalignment when riveting.

[0085] 2) Patterning: Apply dry film, and create the L5 pattern based on the left and right partitions, adjusting for expansion and contraction. L5 is also a non-positioning layer, and its target pattern is offset from the targets of positioning layers like L2 and L4. Subsequent pattern etching is performed according to conventional processes.

[0086] 5. Make the secondary laminate (final) and produce the L1 and L6 layer graphics of the secondary laminate. The specific steps are as follows:

[0087] 1) Lamination: The first-level laminate and the third core board are browned / blackened; the second lamination bonding sheet is prepared, and the blind slot positions corresponding to the blind holes in the 1-4 layers are opened by laser milling; the second lamination is performed according to the bonding sheet lamination process requirements to form the second-level laminate.

[0088] 2) Target Drilling: X-ray drilling is performed according to the L4 layer's primary target pattern to form secondary positioning holes and measure their expansion and contraction data. Primary positioning holes are also drilled for later blind slot positioning. This ensures alignment between the L2 layer pattern and the primary positioning holes, and between the L4 layer pattern and the secondary positioning holes.

[0089] 3) Drill through holes: According to the left and right partitions, drill the left partition through holes and the right partition through holes according to the secondary positioning holes.

[0090] 4) Hole plating: According to the conventional microwave board hole metallization process, complete the copper plating in the hole.

[0091] 5) Patterning: Apply dry film and, based on the left and right partitions, produce the L1 and L6 patterns using conventional processes. At this point, the cumulative expansion and contraction between individual panels may be inconsistent. When using LDI exposure, the device's adaptive expansion and contraction can be utilized, with secondary positioning holes for positioning.

[0092] 6) The whole board is nickel-gold plated.

[0093] 6. Blind slot opening and local etching. According to the positioning holes of each layer, open the window to expose the bottom metallized through hole. The specific steps are as follows:

[0094] 1) Use a high-precision depth-controlled mechanical milling machine for window opening operations. The depth control accuracy of the equipment should be adapted to the thickness of the protective film.

[0095] 2) Use the first-level positioning hole for positioning, divide it into left and right areas, and perform window opening operation on the 1-2 layer welding metallization hole position to expose the protective film, and ensure that the center of the window position is aligned with the center of the L2 layer graphic welding hole position.

[0096] 3) Use the secondary positioning holes for positioning, divided into left and right areas, and perform window operations on the positions of the 1-4 layer welding metallization holes to expose the protective film, ensuring that the center of the window position is aligned with the center of the L4 layer graphic welding hole position.

[0097] 4) Use a tool or other tooling to remove the protective film and residual glue at the bottom of the blind slot to expose the metallized hole pattern pad. Be careful not to damage the pad and surface coating during the operation to prevent affecting the welding quality.

[0098] 5) Apply dry film to protect other locations except the blind groove, and perform alkaline etching to remove the unreliable copper plating layer after the secondary copper plating in the blind hole. Because the 1-2 layer solder metallized holes and 1-4 layer solder metallized holes have undergone secondary copper plating after the primary nickel-gold plating treatment, the secondary copper plating is the blind hole copper plating layer, which has the problems of poor copper plating quality and uneven thickness (tapered holes), and should be etched away.

[0099] Obviously, the above embodiments of the present invention are merely examples to more clearly illustrate the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A process for manufacturing an ultra-long microwave printed circuit board with a welding hole at the bottom of a blind slot, comprising: 1) Split the large-size project file into left and right partition project files, set positioning holes in each partition, and perform machining in the partition; 2) Produce the first core board, which includes the L1 and L2 layers. According to the left and right partitions, make the 1-2 layers of metalized blind vias, L2 layer patterns, and primary positioning targets of the first core board. Nickel-gold is plated in and around the blind vias of the L2 layer patterns and a protective film is applied. The specific steps are as follows: 2-1) Drill primary positioning holes, rivet holes, and 1-2 layers of blind holes in the left partition of the first core plate according to the left and right partitions, and make primary positioning holes, rivet holes, and 1-2 layers of blind holes in the right partition according to the right end positioning holes of the left partition; 2-2) Copper plating inside the hole; 2-3) Apply dry film, measure the expansion and contraction data of the positioning holes in the X and Y directions, and adjust the film data according to the expansion and contraction values. According to the left and right partitions, produce the L2 layer pattern and the primary positioning target pattern on this layer; 2-4) The L2 layer pattern is located in and around the blind vias in layers 1-2 and needs to be grooved to expose the exposed parts and perform local nickel-gold plating on the surface; 2-5) The exposed parts around the blind holes in the 1-2 layers need to be grooved and partially protected with a high-temperature resistant protective film; 3) Produce the second core plate, which includes the L3 layer and the L4 layer. The L3 layer pattern of the second core plate is produced according to the left and right partitions. The data of the L3 layer pattern is adjusted according to the expansion and contraction data after the production of the first core plate, and the L3 layer target pattern is produced in a staggered manner from the L2 layer. The specific steps are as follows: 3-1) Drill positioning holes and rivet holes for the left and right partitions of the second core plate according to the data after the expansion and contraction of the first core plate, and align them with the rivet holes after the expansion and contraction of the first core plate; 3-2) Apply dry film, and make L3 layer pattern according to the left and right partitions and the data after adjusting the expansion and contraction. The target pattern of L3 layer is staggered and distinguished from that of L2 layer; 4) The first core board and the second chip are laminated for the first time to form a primary laminate. According to the left and right partitions, the first-level laminate 1-4 layers of metalized blind holes, L4 layer patterns and primary positioning targets are produced. The L4 layer primary positioning targets do not overlap with the L2 layer primary positioning targets and L3 layer target patterns. The blind holes in the L4 layer patterns and the surrounding areas are partially gold plated and covered with protective film. The specific steps are as follows: 4-1) Browning / blackening the first and second core boards; preparing the first lamination bonding sheet, and using laser milling to open windows at the blind slot positions corresponding to the blind holes in the first and second layers, and performing the first lamination to form a first-level laminate; 4-2) Perform X-ray drilling according to the L2 layer primary positioning target pattern to form the primary positioning hole, and measure its expansion and contraction data to align the L2 layer pattern, primary positioning target pattern, and primary positioning hole of each individual plate; 4-3) According to the left and right partitions, drill the first-level rivet holes and blind holes on the 1st to 4th layers of the left partition and the first-level rivet holes and blind holes on the 1st to 4th layers of the right partition according to the first-level positioning holes; 4-4) Copper plating inside the hole; 4-5) Create the L4 layer pattern using the same steps as the L2 layer. The first-level target pattern contained in the L4 layer pattern does not overlap with the target patterns of the L2 and L3 layers, so they are created separately. 4-6) The L4 layer pattern is located in and around the 1-4 blind holes and needs to be grooved to expose the exposed part, and then locally gold-plated and covered with a protective film; 5) Producing the third core board, which includes L5 and L6 layers. The L5 layer pattern of the third core board is produced according to the left and right partitions. The L5 layer pattern data is adjusted according to the expansion and contraction data after the production of the first-level pressed board. The target pattern of the L5 layer is staggered and distinguished from the targets of the positioning layers including the L2 and L4 layers. 6) Laminating the primary laminate and the third chip for a second time to form a secondary laminate, and producing through holes in layers 1-6 and L1 and L6 patterns on the secondary laminate according to the left and right partitions; 7) According to the positioning holes of each layer, open windows to expose the bottom metallized through-holes and perform local etching. The specific steps are as follows: 7-1) Use the first-level positioning holes for positioning, divided into left and right areas, and open windows at the positions of the 1-2 layer welding metallization holes to expose the protective film, ensuring that the center of the window position is aligned with the center of the L2 layer pattern welding hole position; 7-2) Use the secondary positioning holes for positioning, divided into left and right areas, to open windows at the locations of the 1-4 layers of soldering metallization holes to expose the protective film, ensuring that the center of the window position is aligned with the center of the L4 layer pattern soldering hole position; 7-3) Remove the protective film and residual glue at the bottom of the blind groove to expose the metallized hole pattern pad; 7-4) Apply dry film to protect other locations except the blind groove, and perform alkaline etching to remove the unreliable copper plating layer after the secondary copper plating in the blind hole.

2. The manufacturing process of an ultra-long microwave printed circuit board with a welding hole at the bottom of a blind slot according to claim 1 is characterized in that: Use LDI exposure equipment to perform two-part exposure operations according to the left and right partition positioning holes to splice out the complete circuit pattern; Use drilling and milling machine equipment to perform two-part drilling and contour operations according to the left and right partition positioning holes, and splice out the complete machining graphics.

3. The manufacturing process of an ultra-long microwave printed circuit board with a welding hole at the bottom of a blind slot according to claim 1 is characterized in that: The high-temperature resistant protective film should withstand a temperature higher than the lamination temperature and remain unchanged at 230°C for more than 6 hours. The high-temperature resistant protective film is made by laser milling and aligned with the center of the blind holes in the first core board layer 1-2. The high temperature resistant protective film is tightly bonded to the first core plate by using hot quick pressing or roller pressing.

4. The manufacturing process of an ultra-long microwave printed circuit board with a welding hole at the bottom of a blind slot according to claim 1 is characterized in that: The specific steps of step 5) are as follows: 5-1) Drill positioning holes and rivet holes for the left and right partitions of the third core plate according to the adjusted expansion and contraction data, and align them with the rivet holes of the first-level press plate; 5-2) Apply dry film, and make L5 layer graphics according to the left and right partitions and the data after adjusting the expansion and contraction. The target graphics of L5 layer are offset and distinguished from the targets of the positioning layer.

5. The manufacturing process of an ultra-long microwave printed circuit board with a welding hole at the bottom of a blind slot according to claim 4 is characterized in that: The specific steps of step 6) are as follows: 6-1) The primary laminate and the third core sheet are browned / blackened, and the bonding sheet for the second lamination is prepared. The blind slot positions corresponding to the blind holes in the 1st to 4th layers are laser milled, and the second lamination is performed to form the secondary laminate; 6-2) Perform X-ray drilling on the target according to the L4 layer primary target pattern to form secondary positioning holes, and measure their expansion and contraction data. Drill the primary positioning holes for later blind slot positioning, so that the L2 layer pattern and the primary positioning holes are aligned, and the L4 layer pattern and the secondary positioning holes are aligned; 6-3) According to the left and right partitions, drill the left partition through holes and the right partition through holes according to the secondary positioning holes; 6-4) Copper plating inside the hole; 6-5) Apply dry film and make L1 and L6 patterns according to the left and right partitions; 6-6) The entire board is nickel-gold plated.

6. An ultra-long microwave printed circuit board with a welding hole at the bottom of a blind groove, manufactured by the manufacturing process of an ultra-long microwave printed circuit board with a welding hole at the bottom of a blind groove according to any one of claims 1 to 5.

Images