Manufacturing method of small-size multilayer circuit board with metalized edge

Abstract

The invention discloses a manufacturing method of a small-size multi-layer circuit board with a metalized edge, which comprises the following steps of: processing the circuit board by using a jointed board structure, arranging a process edge and a board splitting line in the board on the jointed board structure, manufacturing an inner-layer core board of the multi-layer circuit board, taking a prepreg and a copper layer, pressing, milling a groove body, and manufacturing the inner-layer core board of the multi-layer circuit board. Sequentially pasting a dry film, exposing, developing and electroplating tin, milling a metalized edge, sequentially etching, stripping the film, stripping tin, manufacturing a solder resist pattern, and carrying out molding processing to form a circuit board; more areas capable of being fixed and positioned are provided by adopting the modes of arranging the plate dividing lines and the like, so that the skew risk during milling forming processing is reduced; the cut-off circuit is manufactured, the conductive strength of the circuit pattern layer and the insulating medium layer is balanced, and the uneven phenomenon generated after metalized edges are electroplated is avoided. Through multi-point fixation on the process edge and the board dividing line, the fixing stability of the circuit board partition is improved, and the problems of milling skew and the like are prevented.

Description

Technical Field

[0001] The invention relates to the field of circuit board processing, and in particular to a method for manufacturing a small-size multilayer circuit board with metallized edges. Background Art

[0002] With the development of industries such as smart connected vehicles and charging equipment, designs that use circuit boards to replace traditional inductive devices have gradually emerged. In a type of coil line module, a coil circuit board is formed in which the coil is designed as a line pattern. The wiring position of the coil end of this type of circuit board uses a metallized edge for electrical connection, which can effectively increase the design breadth of the electrical connection and increase the line density of the circuit board, forming a high-density circuit board product with a smaller volume and greater functions.

[0003] For this type of small-sized multi-layer circuit boards with metallized edges, the traditional multi-layer circuit board processing method is generally used. That is, the multi-layer circuit boards are first manufactured according to the process, and then the grooves are milled in the metallized edge area, electroplating and surface treatment are performed, and then molding is performed to form the finished product.

[0004] The main disadvantages of this production method are: (1) Due to the position of the metallized edge of the multi-layer circuit board, the corresponding inner core board pattern has a strong conductivity during electroplating, while the insulating medium layer between each circuit pattern layer has a weak conductivity, resulting in unevenness of the metallized edge after electroplating; (2) Since the electroplating and surface treatment layers formed in the slot body need to be cut off during the forming process and milling, it is easy to produce burrs during cutting, which affects the flatness and quality of the metallized edge; (3) For small-sized multi-layer circuit boards, the general method of panelization is adopted. However, if multiple unit circuit boards are directly panelized, during the milling and forming process, due to the large number of unit circuit boards, as the forming and milling proceed, it is easy to produce problems such as insufficient board support and skewed milling, resulting in reduced processing accuracy. In addition, when forming the unit circuit boards, if they are not taken out in time, there is a risk of circuit board accumulation, resulting in problems such as circuit board jamming and milling cutter breaking.

[0005] Based on the above background and problems, it is necessary to provide a manufacturing method that can systematically and effectively improve the processing quality of small-sized multi-layer circuit boards with metallized edges. Summary of the invention

[0006] The present invention aims at the problems of uneven metallized edges, burrs, and low milling precision in the processing of small-sized multilayer circuit boards with metallized edges in the prior art, and the problems of stuck boards and broken milling cutters. A method for manufacturing a small-sized multilayer circuit board with metallized edges is provided, and the manufacturing method comprises the following steps: S10: The circuit board is an independent unit circuit board. During the design of data and the processing, a number of the unit circuit boards are assembled into a panel structure; the panel structure is provided with a process edge, and a panel dividing line passing through two parallel process edges is provided in the middle position within the range of the process edge, and the unit circuit boards are evenly distributed in the enclosed area formed by the process edge and the panel dividing line to form a unit area panel; S20: The multilayer circuit board includes an inner core board, and a copper clad board is taken to make an inner circuit pattern to form the inner core board; S30: taking the prepreg and the copper layer, and pressing them with the inner core board to form a pressed board; S40: milling the groove body of the pressed plate, then sequentially applying dry film, exposing, developing, and electroplating tin, then milling out the metallized edge according to the distribution position of the metallized edge, and then sequentially etching, stripping the film, and stripping the tin; forming an outer layer graphic board; the development is to develop away the dry film covering the surface of the copper layer that does not need to be etched, including developing away the dry film covering the groove body; S50: making a solder resist pattern on the outer pattern board to form an integrally completed board, and performing molding processing; forming the small-sized multi-layer circuit board with metallized edges.

[0007] Furthermore, the panel structure also includes: two adjacent edges of each unit area panel are provided with "L"-shaped edges.

[0008] Furthermore, the inner core board is designed with a milling groove area pattern of a metallized edge; the making of the inner circuit pattern includes making a cutting pattern to remove the inner circuit pattern of the milling groove area pattern perpendicular to the metallized edge.

[0009] Furthermore, the width of the cut pattern is 70 μm to 210 μm, preferably 105 μm or 150 μm.

[0010] Furthermore, the milling of the groove body is to mill the area outside the graphic range of the unit circuit board according to the distribution position of the metallized edge to form the groove body.

[0011] Furthermore, pin holes are provided on the process edge and the board dividing line, and the molding process is to use pins to fix the integral finished board to the table of the molding equipment through the pin holes, and to perform milling and molding of the unit circuit boards one by one.

[0012] Optionally, whole-plate pin holes are provided on the process edge, and unit-area panel pin holes are provided on the "L"-shaped edge; the overall completed plate is fixed to the table top of the molding equipment through the whole-plate pin holes by using pins, and the unit-area panel is milled and formed to form a unit plate; the unit plate is fixed to the table top of the molding equipment through the unit-area panel pin holes by using pins, and the unit circuit boards are milled and formed one by one.

[0013] Furthermore, the milling and shaping the unit circuit boards one by one includes, when performing the milling and shaping one by one, taking out the milled unit circuit boards one by one.

[0014] Furthermore, the taking out one by one is performed by suction using a vacuum cleaner.

[0015] Furthermore, the length of the unit circuit board is less than or equal to 50 mm, and the width is less than or equal to 50 mm.

[0016] The technical solution of the present invention adopts methods such as setting a panel splitting line to form a new panel structure, provide more fixed positioning areas, and reduce the risks of skewness and mutual influence during circuit board processing and milling and forming processing; adopts the method of cutting the circuit when making the inner layer circuit pattern to balance the conductivity of the circuit pattern layer and the insulating medium layer during electroplating, and avoid the unevenness of the metallized edge after electroplating; through multi-point fixation on the process edge and the panel splitting line, the fixing stability of the circuit board partition is improved, and the unit circuit board processed by milling and forming is prevented from skew, and the circuit board is taken out in time to prevent the risk of circuit board accumulation, and avoid problems such as board jamming and milling cutter breaking; the overall processing process forms an effective matching process, which effectively improves the processing quality of small-size multi-layer circuit boards with metallized edges. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0018] Figure 1 The main process flow chart of the embodiment of the present invention is included; Figure 2 This is a schematic plan view of the panel structure of this embodiment; Figure 3 A schematic plan view of the design data of the panel structure of this embodiment; Figure 4This is a physical picture of the uneven metallization edge problem in this embodiment; Figure 5 Schematic diagram of the planar structure of the inner core board of the unit circuit board of this embodiment; Figure 6 is a schematic diagram of the cross-sectional structure of a pressing plate of a unit circuit board of this embodiment; Figure 7 is a schematic diagram of the cross-sectional structure of a small-sized multi-layer circuit board with metallized edges according to this embodiment; Figure 8 This is a physical picture of a small-sized multi-layer circuit board with metallized edges according to this embodiment.

[0019] Description of Figure Numbers:

[0020] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, inside, outside...) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0023] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0024] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0025] See also Figure 1 ; Figure 1 The main process flow chart included in the embodiment of the present invention.

[0026] A method for manufacturing a small-size multilayer circuit board with metallized edges according to an embodiment of the present invention comprises: Figure 1 The key production process is described in detail step by step as follows.

[0027] See also Figure 2 and Figure 3 ; Figure 2 This is a schematic plan view of the panel structure of this embodiment; Figure 3 It is a plan view of the design data of the panel structure of this embodiment.

[0028] Step S10: The circuit board is an independent unit circuit board 100. When designing data and in the process of processing, several unit circuit boards 100 are assembled into a panel structure 10. The panel structure 10 is provided with a process edge 110. A panel dividing line 120 passing through two parallel process edges is provided in the middle position within the process edge 110. The unit circuit boards 100 are evenly distributed in the enclosed area formed by the process edge 110 and the panel dividing line 120 to form a unit area panel.

[0029] The present embodiment sets a panel splitting line 120, which transforms the large panel of the prior art into a large panel composed of multiple unit area panels, providing a basis for fixing the overall completed board by pins at multiple positions for the subsequent milling of the groove body in the process and the final forming and milling processing, dispersing the positioning position of the overall completed board, improving the positioning stability of the overall circuit board, and reducing problems such as skewness of the circuit board caused by the milling and forming processing.

[0030] Optionally, both the board splitter 120 and the multi-layer circuit board are multi-layer structures, and each layer thereof includes a circuit pattern of a copper layer, which is conducive to the tightening of the pins.

[0031] Optionally, the panel splitting lines 120 may be arranged in both the longitudinal and transverse directions, and more than or equal to two parallel lines may be arranged.

[0032] Optionally, the width of the splitting line 120 is 5 mm to 10 mm.

[0033] In this embodiment, the length of the unit circuit board 100 is less than or equal to 50 mm, and the width is less than or equal to 50 mm.

[0034] This embodiment is generally aimed at processing circuit boards of smaller sizes, improving the stability of the process and the accuracy of the milling and forming process.

[0035] In this embodiment, two adjacent edges of each unit area panel are provided with "L" shaped edges 130. The "L" shaped edges 130 are provided to facilitate the process processing, and the various fixation and processing options of the milling and forming processing. The process processing can be more firmly supported and positioned by the "L" shaped edges 130. The milling and forming processing can choose to first mill and form each unit board, and then fix it by the "L" shaped edges 130 to perform the milling and forming processing of the unit circuit board 100, or can choose to fix and mill the unit circuit board 100 by a single condition fixation or a combined condition fixation method of the process edge, the panel dividing line, and the "L" shaped edge 130 at one time, effectively preventing the unit circuit board 100 from being skewed during the milling and forming processing, and reducing the problems of the circuit board being stuck and the milling cutter being broken during the milling and forming processing.

[0036] Optionally, the width of the “L”-shaped side 130 is 5 mm to 10 mm.

[0037] See also Figures 4 to 6 ; Figure 4 This is a physical picture of the uneven metallization edge problem in this embodiment; Figure 5 Schematic diagram of the planar structure of the inner core board of the unit circuit board of this embodiment; Figure 6 It is a schematic diagram of the cross-sectional structure of the pressing plate of the unit circuit board of this embodiment.

[0038] Step S20: The multilayer circuit board includes an inner core board, a copper clad board, and an inner circuit pattern 210 to form an inner core board. Figure 5 The inner core board 20 of the manufactured unit circuit board is shown in FIG. 1 , wherein the copper-clad board includes an insulating dielectric layer 230 , and the indicator line of the final forming of the unit circuit board 100 is a forming line 200 .

[0039] In this embodiment, the inner core board is designed with a milling groove area pattern 220 of the metallized edge; making the inner circuit pattern 210 includes making a cutting pattern 2110 to remove the inner circuit pattern 210 perpendicular to the milling groove area pattern 220 of the metallized edge.

[0040] In this embodiment, the width of the cut pattern is 70 μm to 210 μm, preferably 105 μm or 150 μm.

[0041] The cutting pattern 2110 is produced to disconnect the metallized edge position corresponding to the inner layer pattern from other patterns, so as to prevent the difference in current conductivity during electroplating of the metallized edge, thereby causing unevenness. The width of the cutting pattern 2110 should generally not be too large, otherwise it will cause problems such as depression and unevenness at the position after pressing. However, it should not be too small, otherwise it will be difficult to produce the effect of disconnecting and cutting off the current. Generally, the metallized edge position corresponding to the outer layer circuit pattern 310 is already a separate circuit pattern, or is generally a circuit pattern that cannot be cut. If there is no special requirement, the metallized edge position corresponding to the outer layer circuit pattern 310 can also be cut.

[0042] Optionally, the cutting pattern 2110 completely or partially cuts off the inner layer circuit pattern of the milling groove area pattern 220 perpendicular to the metallization edge.

[0043] If the inner layer circuit pattern at this position does not need to form an electrical connection effect, but only needs to form an electroplating effect to support the metallized edge and enhance the electroplating adhesion strength of the metallized edge, it can be completely cut off; if electrical connection is required, it can be partially cut off.

[0044] Step S30: Take the semi-cured sheet and the copper layer, and press them with the inner core board 20 to form a pressed board 30. To clearly illustrate the distribution of the cutting pattern, Figure 6 The cross-sectional structure 30 of the pressed plate corresponds to Figure 5 The structure of the AA section of the inner core panel 20.

[0045] Step S40: The pressing plate 30 is milled to cut the groove body, and then the dry film is attached, exposed, developed, and electroplated with tin in sequence. Then, the metallized edge is milled out according to the distribution position of the metallized edge, and then etched, film stripped, and tinned in sequence to produce the outer layer circuit pattern 310 to form an outer layer graphic board; the development is to develop away the dry film covering the surface of the copper layer that does not need to be etched, including developing away the dry film covering the groove body.

[0046] In this embodiment, the groove body is milled to form the groove body by milling the area outside the graphic range of the unit circuit board 100 according to the distribution position of the metallized edge.

[0047] In the process of making the outer layer circuit pattern 310, the groove body and electroplating of the metallized edge are made together. The electroplating is carried out before etching and tin plating is used for protection. After the tin plating is completed, the metallized edge is milled out, and the burrs that may be formed on the copper layer circuit pattern are exposed. After etching, the burrs can be effectively removed.

[0048] The metallized edge can be milled out by extending the slot body to both ends by a certain distance, for example, by milling a width of 200 μm to 2.0 mm.

[0049] Please refer again Figure 2 , and see Figure 7 , Figure 8 ; Figure 7 is a schematic diagram of the cross-sectional structure of a small-sized multi-layer circuit board with metallized edges according to this embodiment; Figure 8 This is a physical picture of a small-sized multi-layer circuit board with metallized edges according to this embodiment.

[0050] Step S50: A solder resist pattern 410 is made on the outer pattern board to form an integrally completed board, and a molding process is performed to form a small-sized multi-layer circuit board 40 with a metallized edge, and a metallized edge 420 is formed at the same time.

[0051] In one embodiment, whole-board pin holes 1110 are distributed on the process edge 110, and split-board line pin holes 1210 are provided on the split-board line 120. The molding process is to use pins to fix the entire completed board to the table of the molding equipment through the whole-board pin holes 1110 and the split-board line pin holes 1210, and the unit circuit boards 100 are milled and formed one by one.

[0052] By using the process edge 110 and the board dividing line 120 for fixing, a more stable fixing effect can be formed, thereby improving the accuracy of the milling and forming process of the unit circuit board 100.

[0053] In one embodiment, a whole-board pin hole is provided on the process edge 110, and a unit-area panel pin hole 1310 is provided on the "L"-shaped edge 130; the overall completed board is fixed to the table of the molding equipment through the whole-board pin hole 1110, and the unit-area panel is milled and formed to form a unit board; the unit board is fixed to the table of the molding equipment through the unit-area panel pin hole 1310, and the unit circuit boards 100 are milled and formed one by one.

[0054] Since the unit circuit board 100 is relatively small and there are no direct positioning holes within its own graphic range, it is impossible to fix each unit circuit board 100. Therefore, the fixing conditions of the process edge and the "L"-shaped edge 130, or the single fixing condition of the "L"-shaped edge 130, or the three combined fixing conditions of the process edge 110, the "L"-shaped edge 130 and the dividing line 120 are used to further enhance the partition fixing effect of the whole board and enhance the stability of the whole board fixation. Optionally, the unit board can be milled and formed first, and then the unit boards can be milled and formed into unit circuit boards 100 one by one, so as to form dispersed small module positioning from the positioning structure of the board body, improve the firmness of the positioning, effectively reduce the risk of whole board processing and the milling influence between boards from the aspect of milling and forming processing, and prevent problems such as skewness in milling.

[0055] In one embodiment, the unit circuit boards 100 are milled and formed one by one, including taking out the milled unit circuit boards 100 one by one during the milling and forming.

[0056] In one embodiment, taking out one by one is done by suction using a vacuum cleaner.

[0057] Since the unit circuit board 100 is relatively small in size, a vacuum cleaner can be used during the milling process to timely mill out the milled unit circuit board, thereby effectively preventing the risk of accumulation and avoiding problems such as board jamming and breaking of the milling cutter.

[0058] It is worth noting that due to the actual design and processing of circuit boards, the actual structure diagram and the thickness of each layer, line width and other dimensions are all in the micron level. For example, the thickness of each layer is generally 5μm to 50μm. If the drawings in the specification are made according to the actual proportion, there will be a problem of unclear drawings. Therefore, in order to more clearly show the implementation process of the manufacturing method, the drawings of this embodiment are all schematic diagrams that enlarge the technical features, which do not represent the size of the actual structure diagram, nor do they represent enlarged views of the actual structure diagram in proportion.

[0059] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for manufacturing a small-size multilayer circuit board with metallized edges, characterized in that: The production method comprises the following steps: S10: The circuit board is an independent unit circuit board. During the design and processing, a plurality of the unit circuit boards are assembled into a panel structure; The panel structure is provided with a process edge, and a panel dividing line penetrating two parallel process edges is provided in the middle position within the range of the process edge. Evenly distributing the unit circuit boards in the enclosed area formed by the process edge and the panel separation line to form a unit area panel; S20: The multilayer circuit board includes an inner core board, and a copper clad board is taken to make an inner circuit pattern to form the inner core board; S30: taking the prepreg and the copper layer, and pressing them with the inner core board to form a pressed board; S40: milling the groove body of the laminated board, and then sequentially applying dry film, exposing, developing, and electroplating tin, and then milling out the metallized edge according to the distribution position of the metallized edge, and then sequentially etching, stripping the film, and stripping the tin to form an outer layer graphic board; The developing step is to develop away the dry film covering the surface of the copper layer that does not need to be etched, including developing away the dry film covering the tank body; S50: making a solder resist pattern on the outer pattern board to form an integrally completed board, and performing molding processing; forming the small-sized multi-layer circuit board with metallized edges.

2. A method for manufacturing a small-sized multi-layer circuit board with metallized edges as claimed in claim 1, characterized in that: The panel structure also includes: Two adjacent edges of each unit area panel are provided with "L" shaped edges.

3. A method for manufacturing a small-sized multi-layer circuit board with metallized edges as claimed in claim 1, characterized in that: The inner core plate is designed with a milling groove area pattern of metallized edges; The manufacturing of the inner layer circuit pattern includes manufacturing a cutting pattern, which is the inner layer circuit pattern that removes the milling groove area pattern perpendicular to the metallized edge.

4. A method for manufacturing a small-sized multi-layer circuit board with metallized edges as claimed in claim 1, characterized in that: The width of the cut pattern is 70 μm to 210 μm, preferably 105 μm or 150 μm.

5. A method for manufacturing a small-sized multi-layer circuit board with metallized edges as claimed in claim 1, characterized in that: The milling groove body is formed by milling the area outside the graphic range of the unit circuit board according to the distribution position of the metallized edge.

6. A method for manufacturing a small-sized multi-layer circuit board with metallized edges as claimed in claim 1, characterized in that: The process edge and the plate dividing line are both provided with pin holes. The molding process is to use pins to fix the integrally completed board to the table of the molding equipment through the pin holes, and to perform milling and molding on the unit circuit boards one by one.

7. A method for manufacturing a small-sized multi-layer circuit board with metallized edges as claimed in claim 2, characterized in that: The process edge is provided with a whole board pin hole, and the "L"-shaped edge is provided with a unit area puzzle pin hole; The whole completed board is fixed to the table of the forming equipment by using pins through the pin holes of the whole board, and the unit area panel is milled and formed to form a unit board; The unit board is fixed to the table of the molding equipment by using pins through the pin holes of the unit area panel, and the unit circuit boards are milled and formed one by one.

8. A method for manufacturing a small-sized multi-layer circuit board with metallized edges as claimed in claim 7, characterized in that: The milling and shaping of the unit circuit boards one by one includes, when the milling and shaping are performed one by one, taking out the milled unit circuit boards one by one.

9. A method for manufacturing a small-sized multi-layer circuit board with metallized edges as claimed in claim 8, characterized in that: The one by one removal is carried out by suction using a vacuum cleaner.

10. A method for manufacturing a small-sized multi-layer circuit board with metallized edges as claimed in claim 1, characterized in that: The unit circuit board has a length less than or equal to 50 mm and a width less than or equal to 50 mm.

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