Low-cost preparation method of ultra-long rigid-flex printed board

Abstract

The invention relates to a low-cost preparation method of a super-long rigid-flex printed board, which is characterized by comprising the following steps of: step 1, designing sections of a first layer of super-long rigid-flex printed board, dividing the first layer of super-long rigid-flex printed board into a plurality of sections according to the length of a first inner layer of super-long rigid-flex printed board, the head section and the tail section are rigid-flex printed boards (10), and the middle sections are flexible printed boards (20); the left end of the head rigid-flex printed board (10) and the right end of the tail rigid-flex printed board (10) are respectively connected with a rigid printed board (1); only one-time pressing is needed in the manufacturing process, the production period is greatly shortened, and compared with a rigid printed board switching method, the welding height of the splicing position is small, and application in a narrow space is facilitated.

Description

Technical Field

[0001] The invention relates to a low-cost preparation method for an ultra-long rigid-flexible printed circuit board, and in particular to a preparation method for an ultra-long rigid-flexible printed circuit board structure, a preparation method for reliable electrical connection, and a low-cost preparation method for an ultra-long rigid-flexible printed circuit board, and belongs to the field of electrical interconnection. Background Art

[0002] With the development trend of aerospace product integration, the number of applications of rigid-flex PCB interconnection products has increased. As the production volume gradually increases, reducing costs is the general trend. The production cost of rigid-flex PCBs increases in a step-by-step manner with the increase in product size. For ultra-long rigid-flex PCBs, since the expansion and contraction consistency of the substrate in a hot environment is difficult to control, the production is difficult, and its price increases exponentially, which seriously restricts the development efficiency and cost control of rigid-flex PCBs.

[0003] In the production process of extra-long rigid-flexible printed circuit boards, due to the limitation of the working size of the laminating equipment, when the external dimensions exceed the bearing capacity, the product needs to be split and produced in sections and assembled through a specific assembly method. The existing assembly methods are mostly "rigid printed circuit board transfer" and "graded lamination", which have problems such as excessive thickness at the splicing position and long production cycle.

[0004] Affected by the product characteristics of rigid-flex PCBs, when a problem occurs in a certain position, the entire product will be scrapped, and the product maintainability is poor. At the same time, in order to control the expansion and contraction of the substrate during the production of ultra-long rigid-flex PCBs, the substrate needs to be fixed in the process area, resulting in a decrease in the utilization rate of the substrate. The above situations have increased the production cost of rigid-flex PCBs to a certain extent, and it is impossible to further achieve a low-cost production model.

[0005] Therefore, it is necessary to study and design a low-cost preparation method for ultra-long rigid-flexible printed circuit boards, which can reduce the difficulty of product production, improve the production yield and maintainability without affecting the installation and use of the product, and thus realize a low-cost production model for the product. Summary of the invention

[0006] To solve the above problems, the patent of this invention proposes a preparation method suitable for ultra-long rigid-flexible printed circuit boards. On the premise of ensuring that the finished product structure and electrical performance meet the use requirements, the product size is divided and pads are introduced to ensure that the divided products can be easily electrically interconnected.

[0007] A low-cost method for preparing an ultra-long rigid-flex printed circuit board, characterized in that it comprises the following steps:

[0008] Step 1: Design the segments of the first layer of super-long rigid-flexible printed circuit board, and divide it into several segments according to the length of the first inner layer super-long rigid-flexible printed circuit board, wherein the first and last segments are rigid-flexible printed circuit boards 10, and the middle segments are all flexible printed circuit boards 20; the left end of the first rigid-flexible printed circuit board 10 and the right end of the tail rigid-flexible printed circuit board 10 are respectively connected with a rigid printed circuit board 1;

[0009] Step 2: The right end of the rigid-flexible printed circuit board 10 at the head is connected with a welding end 2 by etching and gold plating, and the left end of the rigid-flexible printed circuit board 10 at the tail is connected with a load-bearing end 3 by etching and gold plating; each middle section is a flexible printed circuit board 20, and the left end of each section of the flexible printed circuit board 20 is connected with a load-bearing end 3, and the right end of each section of the flexible printed circuit board 20 is connected with a welding end 2. The welding end 2 and the load-bearing end 3 are respectively designed for the receiving end and the welding end wiring before connection; the welding end 2 is provided with a welding end positioning hole 51, and the load-bearing end 3 is provided with a load-bearing end positioning hole 52, and the welding end positioning hole 51 matches the load-bearing end positioning hole 52, which is used for auxiliary docking in the subsequent welding process;

[0010] Step 3: A welding end pad 7 is provided on the welding end 2, and a receiving end pad 8 is provided on the receiving end 2; a conductive via 4 is provided on the welding end pad 7 to improve solder fluidity and ensure welding quality; a receiving end reinforcing plate 9 is attached to the back of the receiving end pad 8 to increase the structural strength of the "receiving end";

[0011] Step 4: The welding end 2 and the load-bearing end 3 of each adjacent rigid-flexible printed circuit board 10 or flexible printed circuit board 20 are connected together by welding the welding end 2; ensuring that the center lines of the welding end positioning hole 51 and the load-bearing end positioning hole 52 are in a straight line;

[0012] Step 5: After welding and passing the test, the welding point is insulated by applying insulating glue, wrapping insulating tape, etc. to form an insulating protection area 6; at this point, the first layer of super-long rigid-flex printed circuit board segmented production is completed;

[0013] Step 6. Similar to Step 1 to Step 5, design and manufacture the second to Nth layers of super-long rigid-flexible printed circuit board segments, wherein the positions of the welding ends 2 and the bearing ends 3 of each layer on the first to Nth layers of super-long rigid-flexible printed circuit board segments do not overlap in the vertical direction, so as to ensure that the thickness of the first to Nth layers after stacking is relatively uniform;

[0014] Step 7: Align the first to Nth layers of the completed ultra-long rigid-flexible printed circuit boards and place them together for lamination connection. The multi-layer rigid printed circuit boards 1 at both ends are connected together by lamination.

[0015] Among them, in step one and step two, before the rigid-flexible printed circuit board 10, the flexible printed circuit board 20, the rigid printed circuit board 1, the welding end 2 and the load-bearing end 3 are connected, the production and testing of each segment of the rigid-flexible printed circuit board 10 and the flexible printed circuit board 20 after segmentation must be completed independently.

[0016] Among them, the welding process must ensure that the load-bearing end is below the welding end, the pads and positioning holes with the same network definition completely overlap, and welding is performed by welding end 2; in order to facilitate welding, the edges of the pads of welding end 2 and load-bearing end 3 must maintain a distance L during welding, and L is 0.5~1mm.

[0017] Beneficial effects of the invention: The invention relates to a low-cost preparation method for ultra-long rigid-flexible printed circuit boards, which can be used to improve the production capacity of rigid-flexible printed circuit boards, reduce production difficulty, save production costs, and improve the maintainability of rigid-flexible printed circuit boards to a certain extent. Compared with the "graded lamination" method, the method involved in the invention only requires one pressing, which greatly shortens the production cycle. Compared with the "rigid printed circuit board transfer" method, the welding height of the splicing position of this method is small, which is conducive to application in narrow spaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention;

[0019] Figure 2 for Figure 1 A top view of

[0020] Figure 3 This is a schematic diagram of the first layer segmented structure of the present invention;

[0021] Figure 4 It is a schematic diagram of the position layout of the welding end 2 and the bearing end 3 of each layer of the present invention;

[0022] Figure 5 It is a schematic diagram of the connection structure between the welding end 2 and the load-bearing end 3 of the present invention.

[0023] Among them, 1 is a rigid printed circuit board, 2 is a welding end, 3 is a receiving end, 4 is a conductive via at the welding end, 51 is a positioning hole at the welding end, 52 is a positioning hole at the receiving end, 6 is an insulating protection area, 7 is a welding end pad, 8 is a load-bearing end pad, and 9 is a receiving end reinforcement plate. DETAILED DESCRIPTION

[0024] A low-cost method for preparing an ultra-long rigid-flex printed circuit board, characterized in that it comprises the following steps:

[0025] Step 1: Design the segments of the first layer of super-long rigid-flexible printed circuit board, and divide it into several segments according to the length of the first inner layer super-long rigid-flexible printed circuit board, wherein the first and last segments are rigid-flexible printed circuit boards 10, and the middle segments are all flexible printed circuit boards 20; the left end of the first rigid-flexible printed circuit board 10 and the right end of the tail rigid-flexible printed circuit board 10 are respectively connected with a rigid printed circuit board 1;

[0026] Step 2: The right end of the rigid-flexible printed circuit board 10 at the head is connected with a welding end 2 by etching and gold plating, and the left end of the rigid-flexible printed circuit board 10 at the tail is connected with a load-bearing end 3 by etching and gold plating; each middle section is a flexible printed circuit board 20, and the left end of each section of the flexible printed circuit board 20 is connected with a load-bearing end 3, and the right end of each section of the flexible printed circuit board 20 is connected with a welding end 2. The welding end 2 and the load-bearing end 3 are respectively designed for the receiving end and the welding end wiring before connection; the welding end 2 is provided with a welding end positioning hole 51, and the load-bearing end 3 is provided with a load-bearing end positioning hole 52, and the welding end positioning hole 51 matches the load-bearing end positioning hole 52, so as to be used for auxiliary docking in the subsequent welding process;

[0027] Step 3: A welding end pad 7 is provided on the welding end 2, and a receiving end pad 8 is provided on the receiving end 2; a conductive via 4 is provided on the welding end pad 7 to improve solder fluidity and ensure welding quality; a receiving end reinforcing plate 9 is attached to the back of the receiving end pad 8 to increase the structural strength of the "receiving end";

[0028] Step 4: The welding end 2 and the load-bearing end 3 of each adjacent rigid-flexible printed circuit board 10 or flexible printed circuit board 20 are connected together by welding the welding end 2; ensuring that the center lines of the welding end positioning hole 51 and the load-bearing end positioning hole 52 are in a straight line;

[0029] Step 5: After welding and passing the test, the welding point is insulated by applying insulating glue, wrapping insulating tape, etc. to form an insulating protection area 6; at this point, the first layer of super-long rigid-flex printed circuit board segmented production is completed;

[0030] Step 6. Similar to Step 1 to Step 5, design and manufacture the second to Nth layers of super-long rigid-flexible printed circuit board segments, wherein the positions of the welding ends 2 and the bearing ends 3 of each layer on the first to Nth layers of super-long rigid-flexible printed circuit board segments do not overlap in the vertical direction, so as to ensure that the thickness of the first to Nth layers after stacking is relatively uniform;

[0031] Step 7: Align the first to Nth layers of the completed ultra-long rigid-flexible printed circuit boards and place them together for lamination connection. The multi-layer rigid printed circuit boards 1 at both ends are connected together by lamination.

[0032] Among them, in step one and step two, before the rigid-flexible printed circuit board 10, the flexible printed circuit board 20, the rigid printed circuit board 1, the welding end 2 and the load-bearing end 3 are connected, the production and testing of each segment of the rigid-flexible printed circuit board 10 and the flexible printed circuit board 20 after segmentation must be completed independently.

[0033] Among them, the welding process must ensure that the load-bearing end is below the welding end, the pads and positioning holes with the same network definition completely overlap, and welding is performed by welding end 2; in order to facilitate welding, the edges of the pads of welding end 2 and load-bearing end 3 must maintain a distance L during welding, and L is 0.5~1mm.

[0034] A technical solution for a low-cost preparation method of an ultra-long rigid-flexible printed circuit board is as follows:

[0035] The structural dimensions of each section of rigid-flex PCB and flexible PCB are determined according to production capacity. The first and last sections are rigid-flex PCBs, and the middle sections are flexible PCBs. The segmentation positions and welding areas are determined on the rigid-flex PCB and flexible PCB. The welding areas between each inner layer are arranged in sequence to avoid the increase of thickness caused by the concentration of solder joints.

[0036] According to the structural assembly requirements, the "connecting end" and "welding end" are determined in two adjacent sections respectively, and the positions of the positioning holes of the "connecting end" and "welding end" are determined for auxiliary docking in the subsequent welding process.

[0037] Conductive vias are added to the pad position of the "welding end" to improve solder fluidity and ensure welding quality. Conductive vias are not allowed to exist at the welding position of the "receiving end" pad, and a reinforcing plate is attached to the back of the pad to increase the structural strength of the "receiving end".

[0038] According to the electrical performance requirements and reliability indicators of the finished product, the wiring design of the "connecting end" and "welding end" are completed respectively. The spatial position of the pads defined by the same network should be the same to ensure the electrical conductivity requirements after docking.

[0039] Independently complete the production and testing of each section of rigid-flex PCB and flexible PCB after segmentation.

[0040] Complete the splicing and welding of adjacent rigid-flex PCBs and flexible PCBs in sequence according to the general assembly drawing. During the welding process of each section of rigid-flex PCB, ensure that the relative spatial position of the "welding end" is above the "receiving end", and the spatial positions of the positioning holes and pads coincide.

[0041] After welding and passing the test, the welding point is insulated by applying insulating glue, wrapping insulating tape, etc.

[0042] Determine the segmentation size according to actual production capacity, and determine the load-bearing end and welding end.

[0043] Positioning holes 5 are respectively arranged at the load-bearing end 3 and the welding end 2, and at the same time, the area sizes of the load-bearing end 3 and the welding end 2 and the spatial positions of the positioning holes 5 are ensured to be consistent.

[0044] According to electrical indicators, pad wiring is performed at the load-bearing end 3 and the welding end 2 respectively to ensure that the size and position of the pads defined by the same network at both ends remain consistent, and a conductive via 4 is set on the welding end pad 7.

[0045] According to the inner layer wiring situation, each inner layer is produced separately, the welding pads of the welding end and the load-bearing end are etched out, and the pads are insulated and protected.

[0046] After the production of each inner layer is completed, it is aligned in the rigid printed circuit board area, laminated as a whole, and the outer layer graphics are produced.

[0047] A reinforcement plate is set on the non-welding surface of the load-bearing end. The reinforcement plate should cover the pad area. If there are vias in the flexure area near the pad, the reinforcement plate area should also cover the via position.

[0048] After each split area is completed, splicing and welding are carried out according to the assembly drawing.

[0049] During welding, the load-bearing end should be ensured to be below the welding end, and the pads and positioning holes of the same network definition should be completely overlapped, and welding should be performed by the welding end. In order to facilitate welding, the edges of the pads at the welding end and the load-bearing end should be kept at a distance L, which is generally 0.5 to 1 mm.

[0050] After welding is completed, the exposed pads and solder joints are electrically insulated to ensure the electrical insulation performance of the welding position.

Claims

1. A low-cost method for preparing an ultra-long rigid-flexible printed circuit board, characterized in that: The following steps are involved: Step 1: design the segmentation of the first layer of ultra-long rigid-flexible printed circuit board, and divide it into several segments according to the length of the first inner layer ultra-long rigid-flexible printed circuit board, wherein the first and last segments are rigid-flexible printed circuit boards (10), and the middle segments are all flexible printed circuit boards (20); the left end of the first rigid-flexible printed circuit board (10) and the right end of the tail rigid-flexible printed circuit board (10) are respectively connected to the rigid printed circuit board (1); Step 2: The right end of the rigid-flexible printed circuit board (10) at the head is connected to a welding end (2) by etching and gold plating, and the left end of the rigid-flexible printed circuit board (10) at the tail is connected to a load-bearing end (3) by etching and gold plating; each middle section is a flexible printed circuit board (20), the left end of each section of the flexible printed circuit board (20) is connected to the load-bearing end (3), and the right end of each section of the flexible printed circuit board (20) is connected to the welding end (2), and the welding end (2) and the load-bearing end (3) are respectively designed for the receiving end and the welding end wiring before connection; the welding end (2) is provided with a welding end positioning hole (51), and the load-bearing end (3) is provided with a load-bearing end positioning hole (52), and the welding end positioning hole 51) matches the load-bearing end positioning hole (52) for auxiliary docking in the subsequent welding process; Step 3: A welding end pad (7) is provided on the welding end (2), and a receiving end pad (8) is provided on the receiving end (2); a conductive via (4) is provided on the welding end pad (7) to improve solder fluidity and ensure welding quality; a receiving end reinforcing plate (9) is attached to the back of the receiving end pad (8) to increase the structural strength of the "receiving end"; Step 4: The welding end (2) and the load-bearing end (3) of each adjacent rigid-flexible printed circuit board (10) or flexible printed circuit board (20) are connected together by welding the welding end (2); ensuring that the center lines of the welding end positioning hole (51) and the load-bearing end positioning hole (52) are in a straight line; Step 5: After welding and passing the test, the welding point is insulated by applying insulating glue, wrapping insulating tape, etc. to form an insulating protection area (6); at this point, the first layer of super-long rigid-flex printed circuit board segmented production is completed; Step 6: Design and manufacture the second to Nth layers of super-long rigid-flexible printed circuit board segments in the same manner as steps 1 to 5, wherein the positions of the welding ends (2) and the bearing ends (3) of each layer on the first to Nth layers of super-long rigid-flexible printed circuit board segments do not overlap in the vertical direction, so as to ensure that the thickness of the first to Nth layers after stacking is relatively uniform; Step 7: Align the first to Nth layers of the completed ultra-long rigid-flexible printed circuit boards and place them together for lamination connection. The multi-layer rigid printed circuit boards (1) at both ends are connected together by lamination.

2. The low-cost preparation method of an ultra-long rigid-flexible printed circuit board according to claim 1 is characterized in that: In step 1 and step 2, before the rigid-flexible printed circuit board (10), the flexible printed circuit board (20), the rigid printed circuit board (1), the welding end (2) and the load-bearing end (3) are connected, the production and testing of each segment of the rigid-flexible printed circuit board (10) and the flexible printed circuit board (20) after segmentation must be completed independently.

3. The low-cost preparation method of an ultra-long rigid-flexible printed circuit board according to claim 1 is characterized in that: During the welding process, it is necessary to ensure that the load-bearing end is below the welding end, the pads and positioning holes with the same network definition are completely overlapped, and welding is performed by the welding end (2); in order to facilitate welding, the edges of the pads of the welding end (2) and the load-bearing end (3) should maintain a distance L during welding, and L is 0.5 to 1 mm.

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