Method for manufacturing small size multilayer circuit board with metallized edge

Abstract

The application discloses a manufacturing method of a small-size multilayer circuit board with a metallized edge, comprising the following steps: using a spliced board structure to process the circuit board, the spliced board structure being provided with a process edge and a board-in split board line, manufacturing an inner layer core board of the multilayer circuit board, taking a prepreg and a copper layer, pressing, milling a groove body, sequentially pasting a dry film, exposing, developing, electroplating tin, milling the metallized edge, sequentially etching, removing the film, removing the tin, manufacturing a solder resist pattern, performing forming processing, and forming the circuit board; the split board line and other modes are used to provide more fixable and positionable areas, reduce the risk of milling and forming processing skewing, the cut-off line is manufactured to balance the conductive strength of the circuit pattern layer and the insulating medium layer, and the phenomenon that the metallized edge is uneven after electroplating is avoided; the fixing stability of the circuit board partition is improved through multi-point fixing on the process edge and the split board line, and problems such as milling skewing are prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit board processing, in particular to a small-size multilayer circuit board manufacturing method with a metallized edge. BACKGROUND

[0002] With the development of intelligent networked vehicles, charging equipment and other industries, the design of using circuit boards to replace traditional inductors has gradually emerged. In a type of coil circuit module, the coil is designed as a circuit pattern to form a coil circuit board. The coil end connection position of this type of circuit board adopts a metallized edge form for electrical connection, which can effectively improve the design breadth of electrical connection and increase the circuit density of the circuit board, forming a high-density circuit board product with smaller size and greater function.

[0003] For this type of small-size multilayer circuit board with a metallized edge, the current general processing method is to first manufacture a multilayer circuit board according to the process, then mill a groove in the area of the metallized edge, perform electroplating and surface treatment, and then perform forming processing to form a finished product.

[0004] The main shortcomings of this manufacturing method are: (1) Since the metallized edge position of the multilayer circuit board corresponds to a strong conductive inner core board pattern during electroplating, while the insulating medium layer between each circuit pattern layer has weak conductivity, the metallized edge after electroplating will have unevenness; (2) During forming processing milling, the electroplated and surface treated layer formed in the groove needs to be cut off, and during cutting, burrs and burrs are easily generated, affecting the flatness and quality of the metallized edge; (3) For small-size multilayer circuit boards, the general processing method is to use a spliced board, but if multiple unit circuit boards are directly spliced, during milling forming processing, due to the large number of unit circuit boards, as the forming milling progresses, it is easy to cause insufficient support force on the board surface and milling skew, resulting in reduced processing precision, and when forming unit circuit boards, if not removed in time, it is easy to cause circuit board stacking risk, causing circuit board jamming and broken milling cutter problems.

[0005] Based on the above background and problems, it is necessary to provide a manufacturing method that can effectively improve the processing quality of small-size multilayer circuit boards with a metallized edge. SUMMARY

[0006] The present application provides a small-size multilayer circuit board manufacturing method with a metallized edge, which includes the following steps:

[0007] S10: The circuit board is an independent unit circuit board. During the design and manufacturing process, several unit circuit boards are assembled into a panel structure. The panel structure is provided with process edges, and a dividing line is provided in the middle position of the process edge range, which runs through two parallel process edges. The unit circuit boards are evenly distributed in the enclosed area formed by the process edge and the dividing line to form a panel per unit area.

[0008] S20: The multilayer circuit board includes an inner core board. A copper-clad board is taken out and an inner layer circuit pattern is made to form the inner core board.

[0009] S30: Take the prepreg and copper layer and press them together with the inner core board to form a laminated plate;

[0010] S40: The lamination plate is milled into a groove, then dry film is applied, exposed, developed, and tin is electroplated in sequence. Then, the metallized edges are milled according to the distribution position of the metallized edges, and then etched, film removed, and tin removed in sequence to form an outer layer pattern board. The development is to develop away the dry film covering the copper layer surface that does not need to be etched, including developing away the dry film covering the groove.

[0011] S50: Fabricate solder resist patterns on the outer layer pattern board to form an integral finished board, and perform molding processing; form the small-sized multilayer circuit board with metallized edges.

[0012] Furthermore, the panel structure also includes: each unit area panel has an "L"-shaped edge on two adjacent edges.

[0013] Furthermore, the inner core board is designed with a milled groove area pattern with a metallized edge; the fabrication of the inner layer circuit pattern includes fabricating a cutting pattern, which is to remove the inner layer circuit pattern that is perpendicular to the milled groove area pattern with the metallized edge.

[0014] Furthermore, the width of the cut pattern is 70 μm to 210 μm, preferably 105 μm or 150 μm.

[0015] Furthermore, the milled groove is formed by milling into an area outside the graphic range of the unit circuit board according to the distribution position of the metallized edge.

[0016] Furthermore, pin holes are provided on both the process edge and the board separation line. The forming process involves using pins to fix the overall finished board to the table of the forming equipment through the pin holes, and then milling the unit circuit boards one by one.

[0017] Optionally, the process edge is provided with whole board pin holes, and the "L"-shaped edge is provided with unit area panel pin holes; the whole finished board is fixed to the table of the forming equipment by using pins through the whole board pin holes, and the unit area panel is milled to form a unit board; the unit board is fixed to the table of the forming equipment by using pins through the unit area panel pin holes, and the unit circuit board is milled one by one.

[0018] Furthermore, the step of milling the unit circuit boards one by one includes removing the milled unit circuit boards one by one during the step of milling.

[0019] Furthermore, the step of removing them one by one is done by using a vacuum cleaner to absorb them.

[0020] Furthermore, the length of the unit circuit board is less than or equal to 50mm, and the width is less than or equal to 50mm.

[0021] This invention employs methods such as setting board separation lines to form a new panel structure, providing more areas for fixed positioning and reducing the risks of skewing and mutual interference during circuit board processing and milling. By creating cut lines during the fabrication of inner layer circuit patterns, the conductivity of the circuit pattern layer and the insulating dielectric layer during electroplating is balanced, avoiding unevenness after metallization edge electroplating. Multi-point fixing along the process edges and board separation lines improves the stability of circuit board partitioning, preventing skewing of unit circuit boards during milling and ensuring timely removal of circuit boards to prevent stacking risks and avoid issues such as board jamming and broken milling cutters. The overall processing forms an effective matching flow, significantly improving the processing quality of small-sized multilayer circuit boards with metallized edges. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating the main processes included in the embodiments of the present invention;

[0024] Figure 2 This is a schematic diagram of the panel structure in this embodiment;

[0025] Figure 3 This is a plan view of the panel structure design data for this embodiment;

[0026] Figure 4 This is a physical image showing the unevenness of the metallized edge in this embodiment;

[0027] Figure 5 This is a schematic diagram of the planar structure of the inner core board of the unit circuit board in this embodiment;

[0028] Figure 6 This is a schematic diagram of the cross-sectional structure of the lamination plate of the unit circuit board in this embodiment;

[0029] Figure 7 This is a schematic diagram of the cross-sectional structure of a small-sized multilayer circuit board with metallized edges according to this embodiment;

[0030] Figure 8 This is a physical image of a small-sized multilayer circuit board with metallized edges according to this embodiment.

[0031] Explanation of icon numbers:

[0032] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that all directional indications (such as up, down, left, right, front, back, inside, outside, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0035] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0036] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0037] Please see Figure 1 ; Figure 1 This is a flowchart illustrating the main processes involved in an embodiment of the present invention.

[0038] The method for fabricating a small-sized multilayer circuit board with metallized edges according to embodiments of the present invention includes: Figure 1 The key manufacturing process is explained in detail step by step below.

[0039] Please see Figure 2 and Figure 3 ; Figure 2 This is a schematic diagram of the panel structure in this embodiment; Figure 3 This is a plan view of the panel structure design data for this embodiment.

[0040] Step S10:

[0041] The circuit board is an independent unit circuit board 100. During the design and manufacturing process, several unit circuit boards 100 are assembled into a panel structure 10. The panel structure 10 is provided with a process edge 110. A partition line 120 is provided in the middle position of the process edge 110, which runs through two parallel process edges. The unit circuit boards 100 are evenly distributed in the enclosed area formed by the process edge 110 and the partition line 120 to form a panel per unit area.

[0042] This embodiment sets up a partition line 120, which transforms the existing large panel into a large panel composed of multiple unit area panels. This provides a foundation for fixing the entire finished board at multiple positions with pins during subsequent milling of the groove and final forming milling. It disperses the positioning position of the entire finished board, improves the positioning stability of the overall circuit board, and reduces problems such as skewing that occur during the milling and forming process of the circuit board.

[0043] Optionally, both the splitting line 120 and the multilayer circuit board are multilayer structures, with each layer including copper circuit patterns, which facilitates the tightening of the pins.

[0044] Optionally, the dividing lines 120 can be set in both the longitudinal and transverse directions, and there can be two or more parallel lines.

[0045] Optionally, the width of the dividing line 120 is 5mm to 10mm.

[0046] 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.

[0047] This implementation method is generally designed for the processing of smaller circuit boards, improving the stability of the processing and the accuracy of milling and shaping.

[0048] In this embodiment, each unit area panel has an "L"-shaped edge 130 on its two adjacent edges. The "L"-shaped edge 130 facilitates various fixing and processing options for process manufacturing and milling. Process manufacturing utilizes the "L"-shaped edge 130 for more robust support and positioning. For milling, each unit panel can be milled first, then fixed using the "L"-shaped edge 130 before milling the unit circuit board 100. Alternatively, it can be fixed and milled simultaneously using a single or combined fixing method involving the process edge, panel separation line, and "L"-shaped edge 130. This effectively prevents problems such as skewing of the unit circuit board 100 during milling and reduces issues like board jamming and broken milling cutters during the process.

[0049] Optionally, the width of the "L"-shaped side 130 is 5mm to 10mm.

[0050] Please see Figures 4 to 6 ; Figure 4 This is a physical image showing the unevenness of the metallized edge in this embodiment; Figure 5 This is a schematic diagram of the planar structure of the inner core board of the unit circuit board in this embodiment; Figure 6 This is a schematic diagram of the cross-sectional structure of the lamination plate of the unit circuit board in this embodiment.

[0051] Step S20:

[0052] A multilayer circuit board includes an inner core board. A copper-clad laminate is used to fabricate the inner layer circuit pattern 210, forming the inner core board. Figure 5 The inner core board 20 of the unit circuit board 100 is shown in the figure, wherein the copper-clad board includes an insulating dielectric layer 230, and the indicator line for the final forming of the unit circuit board 100 is the forming line 200.

[0053] In this embodiment, the inner core board is designed with a milled groove area pattern 220 with a metallized edge; the fabrication of the inner layer circuit pattern 210 includes the fabrication of a cutting pattern 2110, which is to remove the inner layer circuit pattern 210 that is perpendicular to the milled groove area pattern 220.

[0054] In this embodiment, the width of the cut pattern is 70μm to 210μm, preferably 105μm or 150μm.

[0055] The cutting pattern 2110 is created to disconnect the metallized edge of the inner layer pattern from other patterns, preventing differences in current conductivity during electroplating of the metallized edge and thus avoiding unevenness. The width of the cutting pattern 2110 should generally not be too large, otherwise it will cause problems such as depression and unevenness after pressing. However, it should not be too small either, otherwise it will be difficult to achieve the effect of disconnecting the connection and interrupting the current. In general, the metallized edge of the outer layer circuit pattern 310 is already a separate circuit pattern, or it is generally a circuit pattern that cannot be cut. If there are no special requirements, the metallized edge of the outer layer circuit pattern 310 can also be cut.

[0056] Optionally, the cut pattern 2110 completely or partially cuts off the inner layer circuit pattern of the milled groove area pattern 220 perpendicular to the metallized edge.

[0057] If the inner layer circuit pattern at this location does not require an electrical connection, but only needs to form an electroplating effect that supports the metallization edge and enhances the electroplating adhesion strength of the metallization edge, then it can be completely cut off; if an electrical connection is required, it can be partially cut off.

[0058] Step S30:

[0059] The prepreg and copper layer are pressed together with the inner core board 20 to form the laminate 30. To clearly illustrate the distribution of the cut patterns... Figure 6 The cross-sectional structure of the pressed plate is 30 corresponding to Figure 5 The structure of the inner core plate 20 with section AA.

[0060] Step S40:

[0061] The lamination board 30 is milled with a groove, then dry film is applied, exposed, developed, and tin is electroplated in sequence. Then, the metallized edges are milled according to the distribution position of the metallized edges, and then etched, film removed, and tin removed in sequence to create the outer layer circuit pattern 310, forming the outer layer pattern board; development is to develop and remove the dry film covering the copper layer surface that does not need to be etched, including developing and removing the dry film covering the groove.

[0062] In this embodiment, the milling groove is formed by milling the area outside the graphic range of the unit circuit board 100 according to the distribution position of the metallized edge.

[0063] During the fabrication of the outer layer circuit pattern 310, the groove for the metallization edge and electroplating are fabricated together. Electroplating is performed before etching and tin plating is used for protection. After tin plating is completed, the metallization edge is milled out. At this time, the burrs and flashes of the copper layer circuit pattern that may be formed are exposed. After etching, the burrs and flashes can be effectively removed.

[0064] To mill a metallized edge, the groove can be extended to both ends by milling a certain distance, for example, milling a width from 200μm to 2.0mm.

[0065] Please refer to it again. Figure 2 Please see Figure 7 , Figure 8 ; Figure 7 This is a schematic diagram of the cross-sectional structure of a small-sized multilayer circuit board with metallized edges according to this embodiment; Figure 8 This is a physical image of a small-sized multilayer circuit board with metallized edges according to this embodiment.

[0066] Step S50:

[0067] A solder mask pattern 410 is fabricated on the outer layer pattern board to form an integral finished board, and then formed into a small-sized multilayer circuit board 40 with metallized edges 420.

[0068] In one embodiment, the process edge 110 is provided with board pin holes 1110, and the board separation line 120 is provided with board separation line pin holes 1210. The forming process is to use pins to fix the whole finished board to the table of the forming equipment through the board pin holes 1110 and the board separation line pin holes 1210, and to mill the unit circuit board 100 one by one.

[0069] By using the process edge 110 and the board separation line 120 for fixing, a more stable fixing effect can be formed, improving the milling and forming accuracy of the unit circuit board 100.

[0070] In one embodiment, the process edge 110 is provided with whole board pin holes, and the "L"-shaped edge 130 is provided with unit area panel pin holes 1310; the whole finished board is fixed to the table of the molding equipment by using pins through the whole board pin holes 1110, and the unit area panel is milled to form a unit board; the unit board is fixed to the table of the molding equipment by using pins through the unit area panel pin holes 1310, and the unit circuit board 100 is milled one by one.

[0071] Since the unit circuit board 100 is small and there are no direct positioning holes within its own graphic range, it is impossible to fix each unit circuit board 100. Therefore, by using 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 combination of the process edge 110, the "L"-shaped edge 130, and the partition line 120, the overall board partition fixing effect is further improved, and the overall board fixing stability is enhanced. Optionally, the unit board is first milled into shape, and then the unit board is milled into unit circuit boards 100 one by one. The positioning structure of the board body forms a dispersed small module positioning, which improves the positioning firmness. From the perspective of milling and forming processing, the risk of overall board processing and the milling influence between boards are effectively reduced, and problems such as milling skew are prevented.

[0072] In one embodiment, the process of milling the unit circuit board 100 one by one includes removing the milled unit circuit boards 100 one by one during the milling process.

[0073] In one implementation, the items are removed one by one by using a vacuum cleaner for adsorption.

[0074] Because the unit circuit board 100 is small in size, a vacuum cleaner can be used simultaneously with the milling process to mill out the milled unit circuit board in a timely manner, effectively preventing the risk of accumulation and avoiding problems such as board jamming and broken milling cutters.

[0075] It is worth noting that, due to the high precision of the circuit boards in the actual design and manufacturing process, the actual structural diagrams and dimensions such as the thickness of each layer and the width of the lines are at the micrometer level. For example, the thickness of each layer is generally between 5μm and 50μm. If the accompanying drawings in the instruction manual are made according to the actual scale, there will be a problem of unclear illustrations. Therefore, in order to more clearly show the implementation process of the manufacturing method, the accompanying drawings in this embodiment are all enlarged schematic diagrams of the technical features, and do not represent the size of the actual structural diagram, nor do they represent enlarged views of the actual structural diagram at the same scale.

[0076] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A method for fabricating a small-sized multilayer circuit board with metallized edges, characterized in that, The manufacturing method includes the following steps: S10: The circuit board is an independent unit circuit board. During the design process and manufacturing process, several of the unit circuit boards are assembled into a panel structure. The panel structure has process edges, and a dividing line is provided at the middle position within the range of the process edges, passing through two parallel process edges. The unit circuit boards are evenly distributed in the area enclosed by the process edge and the board separation line to form a unit area panel; the panel structure also includes: each unit area panel has an "L" shaped edge on two adjacent edges. S20: The multilayer circuit board includes an inner core board. A copper-clad board is taken out and an inner layer circuit pattern is made to form the inner core board. The inner core board is designed with a milled groove area pattern with a metallized edge; the fabrication of the inner layer circuit pattern includes the fabrication of a cutting pattern, which is to remove the inner layer circuit pattern that is perpendicular to the milled groove area pattern with the metallized edge. S30: Take the prepreg and copper layer and press them together with the inner core board to form a laminated plate; S40: Mill the grooves on the laminating plate, then sequentially apply dry film, expose, develop, and electroplate tin, then mill the metallized edges according to the distribution of the metallized edges, and then sequentially etch, remove film, and remove tin; to form the outer layer pattern board; The development refers to developing away the dry film covering the surface of the copper layer that does not require etching, including developing away the dry film covering the tank. The milling groove is formed by milling into an area outside the graphic range of the unit circuit board according to the distribution position of the metallized edges; S50: Fabricate solder resist patterns on the outer layer pattern board to form an integral finished board, and perform molding processing; form the small-sized multilayer circuit board with metallized edges.

2. The method for manufacturing a small-sized multilayer circuit board with metallized edges as described in claim 1, characterized in that, The width of the cut pattern is 70 μm to 210 μm.

3. The method for manufacturing a small-sized multilayer circuit board with metallized edges as described in claim 1, characterized in that, Pin holes are provided on both the process edge and the board separation line. The forming process involves using pins to fix the integral finished board to the table of the forming equipment through the pin holes, and then milling the unit circuit boards one by one.

4. The method for manufacturing a small-sized multilayer circuit board with metallized edges as described in claim 1, characterized in that, The process edge is provided with whole board pin holes, and the "L" shaped edge is provided with unit area splicing board pin holes; The integral finished 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 splicing board is milled to form a unit board. The unit board is fixed to the table of the forming equipment by using pins through the pin holes of the unit area panel, and the unit circuit board is milled one by one.

5. The method for manufacturing a small-sized multilayer circuit board with metallized edges as described in claim 4, characterized in that, The step of milling the unit circuit boards one by one includes removing the milled unit circuit boards one by one during the milling process.

6. The method for manufacturing a small-sized multilayer circuit board with metallized edges as described in claim 5, characterized in that, The process of removing them one by one involves using a vacuum cleaner to absorb them.

7. The method for manufacturing a small-sized multilayer circuit board with metallized edges as described in claim 1, characterized in that, The length of the unit circuit board is less than or equal to 50mm, and the width is less than or equal to 50mm.

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