Flexible circuit board connector welding method and flexible circuit board

Abstract

The present application is applicable to the technical field of flexible circuit boards, and proposes a method for soldering a connector on a flexible circuit board, including: providing a flexible circuit board, on which a connector pad is provided; printing solder paste on the surface of the flexible circuit board, wherein part of the solder paste covers the connector pad as a tin protective layer; pasting a nickel sheet on the flexible circuit board; reflowing the flexible circuit board to fix the nickel sheet on the flexible circuit board through the solder paste; pasting a protective film on the surface of the flexible circuit board, and pressing and baking the protective film; and soldering the connector to the connector pad. The present application also proposes a flexible circuit board. The above-mentioned method for soldering a connector on a flexible circuit board can prevent oxidation of the connector pad during processing, and the soldering performance of the connector pad is good.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit boards, and in particular to a flexible circuit board connector welding method and a flexible circuit board. Background Art

[0002] With the popularization of new energy vehicles, the device welding and protection technology on the flexible circuit board used by new energy power batteries is one of the key factors in the development of new energy vehicle technology. Nickel sheets and connectors need to be welded on the flexible circuit board of the power battery pack. In order to enhance the welding strength of the nickel sheet, a polyimide (PI) protective film will be pasted on the nickel sheet after welding. Due to the large size of the DIP connector, the pressing process of the PI protective film cannot be realized. Therefore, the nickel sheet and the DIP connector cannot be welded at the same time. The DIP connector can only be welded after the nickel sheet is welded and the PI protective film is pressed. However, this process will cause the connector pad to be heated multiple times, and the connector pad will be oxidized due to long-term exposure to the air, thereby reducing the welding performance. Summary of the invention

[0003] The present application provides a flexible circuit board connector welding method and a flexible circuit board to solve the problem that the connector pad is oxidized during processing and the welding performance is reduced.

[0004] The first aspect of the present application provides a flexible circuit board connector welding method, comprising:

[0005] Providing a flexible circuit board, wherein the flexible circuit board is provided with a connector pad;

[0006] Printing solder paste on the surface of the flexible circuit board, wherein a portion of the solder paste covers the connector pad to serve as a tin protective layer;

[0007] Pasting a nickel sheet on the flexible circuit board;

[0008] Reflow soldering is performed on the flexible circuit board to fix the nickel sheet on the flexible circuit board through solder paste;

[0009] Laminating a protective film on the surface of the flexible circuit board, and performing pressing and baking;

[0010] Solder the connector onto the connector pad.

[0011] In some embodiments, the connector pad is an annular pad and a plug hole is provided in the middle of the annular pad, and the tin protective layer covers the annular pad and avoids the plug hole.

[0012] In some embodiments, printing solder paste on the surface of the flexible circuit board includes:

[0013] A printing steel mesh is provided, wherein a window portion and a shielding portion are provided on the printing steel mesh, wherein the shielding portion corresponds to the plug hole, and the size of the shielding portion is greater than or equal to the size of the plug hole; the window portion surrounds the circumference of the shielding portion and corresponds to the annular pad;

[0014] Placing the printed steel mesh above the flexible circuit board;

[0015] The solder paste is printed on the surface of the flexible circuit board through the printed steel mesh, and the solder paste is covered on the annular pad through the window portion to form the tin protective layer.

[0016] In some embodiments, the window portion includes a first half ring and a second half ring that are relatively arranged and have the same radius, and two spaced first connecting portions are formed between the first half ring and the second half ring, and the two first connecting portions are respectively connected to both sides of the shielding portion.

[0017] In some embodiments, the window portion also includes a third half ring and a fourth half ring relative to each other, two spaced second connecting portions are formed between the third half ring and the fourth half ring, and the third half ring and the fourth half ring are arranged outside the first half ring and the second half ring; two first connecting portions and two second connecting portions are alternately and spaced apart on the periphery of the shielding portion.

[0018] In some embodiments, the end of the first half ring protrudes toward the direction close to the shielding portion; and / or the end of the first half ring protrudes toward the direction away from the shielding portion.

[0019] In some embodiments, soldering the connector to the connector pad includes:

[0020] Inserting the pins of the connector into the corresponding plug holes of the connector pads;

[0021] Spraying flux onto the pins of the connector and the connector pads, and preheating them;

[0022] Selective wave soldering is performed on the position of the connector pad to melt the tin protective layer and form a wave-shaped extension pin, so as to fix the pin of the connector and solder it to the connector pad.

[0023] In some embodiments, before the connector pins are inserted into the corresponding plug holes of the connector pads, the flexible circuit board is placed on a welding carrier; after the connector pins are inserted into the corresponding plug holes of the connector pads, the connector is fixed using a locking block.

[0024] In some embodiments, when the flexible circuit board is reflowed, a nitrogen reflow oven is used to reflow the flexible circuit board.

[0025] A second aspect of the present application provides a flexible circuit board, which is manufactured using the flexible circuit board connector welding method as described in the first aspect.

[0026] The above-mentioned flexible circuit board connector welding method first prints solder paste on the surface of the flexible circuit board so that the connector pad is covered with a tin protective layer, and then nickel sheet is attached and reflow soldering is performed; before the connector is welded, the tin protective layer can protect the connector pad, so the above-mentioned method can avoid the connector pad being heated multiple times and exposed to the air for a long time to cause oxidation and cause the welding performance to deteriorate, and effectively improves the connector welding quality. The flexible circuit board manufactured by the above-mentioned flexible circuit board connector welding method has better welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 is a flow chart of a flexible circuit board connector welding method provided by an embodiment of the present invention;

[0029] Figure 2 It is a schematic diagram of the structure of the connector pad in the flexible circuit board provided in the embodiment of the present application;

[0030] Figure 3 It is a partial schematic diagram of the flexible circuit board provided in the embodiment of the present application after being affixed with a nickel sheet and a protective film;

[0031] Figure 4 is a partial schematic diagram of a printing steel mesh provided in an embodiment of the present application;

[0032] Figure 5 yes Figure 4 A schematic diagram of the structure of the window opening part and the shielding part in the printed steel mesh shown;

[0033] Figure 6 is a schematic structural diagram of a window portion and a shielding portion in a printing steel mesh provided by another embodiment;

[0034] Figure 7 is a schematic structural diagram of a window portion and a shielding portion in a printing steel mesh provided in yet another embodiment;

[0035] Figure 8It is a schematic diagram of the flexible circuit board provided in the embodiment of the present application during the selective wave soldering process.

[0036] The meanings of the marks in the figure are:

[0037] 100, flexible circuit board; 10, connector pad; 101, plug hole; 20, solder paste; 30, nickel sheet; 40, protective film; 50, connector; 51, pin; 200, printed steel mesh; 210, window portion; 211, first half ring; 212, second half ring; 213, third half ring; 214, fourth half ring; 220, shielding portion; 230, first connecting portion; 240, second connecting portion. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings, i.e., embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly or indirectly on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0040] It should also be noted that, in the embodiments of the present application, the same figure mark is used to represent the same component or the same part. For the same parts in the embodiments of the present application, the figure may only mark one of the parts or components as an example. It should be understood that the figure mark also applies to other identical parts or components.

[0041] In order to illustrate the technical solution of the present invention, the following is a description with reference to specific drawings and embodiments.

[0042] The first aspect of the present application provides a flexible circuit board connector welding method for welding a nickel sheet and a connector on a flexible circuit board. The flexible circuit board can be used in energy-saving power batteries or other products. Please refer to Figure 1 , the flexible circuit board connector welding method includes:

[0043] Step S110: providing a flexible circuit board, on which a connector pad is disposed.

[0044] Please refer to Figure 2 , Figure 2The structure of a group of connector pads 10 in an embodiment is illustrated. A plurality of connector pads 10 are arranged in an array, and each connector pad 10 is used to solder a pin of a connector 50 .

[0045] Step S120: printing solder paste on the surface of the flexible circuit board, wherein a portion of the solder paste covers the connector pad 10 to serve as a tin protection layer.

[0046] Specifically, a printed steel mesh may be used to print solder paste on the surface of the flexible circuit board so that the solder paste covers the position where soldering is required, wherein solder paste is also printed on the connector pad 10, and the solder paste covered by the connector pad 10 serves as a tin protective layer of the connector pad 10. Therefore, the connector pad 10 may be pre-tinned through this step.

[0047] Step S130: Paste a nickel sheet on the flexible circuit board.

[0048] Please refer to Figure 3 Optionally, a plurality of nickel sheets 30 are attached to the flexible circuit board 100, and the nickel sheets 30 can play a role in corrosion prevention. The nickel sheets 30 are fixed to the flexible circuit board 100 by solder paste 20. In this step, NTC chips or other components can also be attached to the flexible circuit board 100 at the same time.

[0049] Step S140 : performing reflow soldering on the flexible circuit board 100 .

[0050] Specifically, the flexible circuit board 100 is passed through a reflow oven to melt the solder paste 20, and the nickel sheet 30 is soldered to the flexible circuit board 100 through the solder paste 20. At the same time, components such as the NTC chip attached to the solder paste 20 are also soldered and fixed. The pre-set tin on the connector pad 10 melts on the pad to form a tin protective layer.

[0051] Optionally, the reflow oven may be an infrared reflow oven.

[0052] In one embodiment, in order to ensure the solder creeping effect at the connector pad 10 , a nitrogen reflow oven may be selected to perform reflow soldering on the flexible circuit board 100 .

[0053] Step S150 : attaching the protective film 40 to the surface of the flexible circuit board 100 , and performing pressing and baking.

[0054] Specifically, the protective film 40 can be a PI film. In order to enhance the peel strength of the nickel sheet 30, the protective film 40 is attached to the upper and lower surfaces of the flexible circuit board 100 and the nickel sheet 30 and high-temperature pressing and high-temperature baking are performed to make the peel strength meet the product requirements. Optionally, the glass strength of the nickel sheet 30 can reach more than 100N.

[0055] The protective film 40 is attached to the surface of the flexible circuit board 100 to enhance the welding strength of the nickel sheet 30 and protect the solder under the nickel sheet 30; the protective film 40 can cover most of the surface of the flexible circuit board 100 and expose the area where the components need to be soldered without affecting the functions of other devices and the soldering performance of the pads.

[0056] Step S160 : soldering the connector onto the connector pad 10 .

[0057] Please refer to Figure 2 , Figure 8 During soldering, the tin protective layer on the connector pad 10 melts to fix the connector 50 on the connector pad 10. In this embodiment, the connector 50 may be a DIP connector, and the connector 50 has a plurality of pins 51, each of which is soldered to a corresponding connector pad 10. Optionally, after step S160, post-processing may be performed, including FR4 reinforcement, glue dispensing, functional testing, etc.

[0058] The above-mentioned flexible circuit board connector welding method first prints solder paste 20 on the surface of the flexible circuit board 100 so that the connector pad 10 is covered with a tin protective layer, and then a nickel sheet 30 is attached and reflow soldering is performed; before the connector 50 is welded, the tin protective layer can protect the connector pad 10, so that the above-mentioned method can prevent the connector pad 10 from being heated multiple times and exposed to the air for a long time to cause oxidation and cause the welding performance to deteriorate, thereby effectively improving the welding quality of the connector 50.

[0059] Please refer to Figure 2 In one embodiment, the connector pad 10 is an annular pad and a plug hole 101 is provided in the middle of the annular pad. The tin protective layer covers the annular pad and avoids the plug hole 101.

[0060] The plug-in hole 101 is used to plug the pin of the connector 50; the tin protective layer covers the annular pad and avoids the plug-in hole 101, so that the connector pad 10 can be covered and protected by the solder paste 20 to avoid copper exposure, and the solder paste 20 can be prevented from flowing into the plug-in hole 101 and affecting the pin insertion.

[0061] Please refer to Figures 1 to 4 In one embodiment, step S120 of printing solder paste 20 on the surface of the flexible circuit board 100 includes the following steps.

[0062] First, a printed steel mesh 200 is provided. The printed steel mesh 200 is provided with a window portion 210 and a shielding portion 220. The shielding portion 220 corresponds to the plug hole 101, and the size of the shielding portion 220 is greater than or equal to the size of the plug hole 101; the window portion 210 surrounds the circumference of the shielding portion 220 and corresponds to the annular pad, the window portion 210 is used for allowing the solder paste 20 to pass through, and the shielding portion 220 is used for shielding the solder paste 20.

[0063] Next, the printed steel mesh 200 is placed above the flexible circuit board 100 , so that the window portion 210 corresponds to the annular pad, and the shielding portion 220 corresponds to the plug hole 101 .

[0064] Then, the solder paste 20 is printed on the surface of the flexible circuit board 100 through the printing steel mesh 200. The solder paste 20 covers the annular pad through the window portion 210 and forms a tin protection layer.

[0065] By adopting the above technical solution, the above method can form an annular tin protective layer on the connector pad 10, which covers the annular pad and avoids the plug hole 101, does not expose the connector pad 10, and can prevent tin from entering the plug hole 101 of the connector pad 10.

[0066] Optionally, before printing the solder paste 20 , the flexible circuit board 100 is positioned according to the carrier slot.

[0067] In one embodiment, the window portion 210 includes a first half ring 211 and a second half ring 212 which are arranged oppositely and have the same radius, and two spaced first connecting portions are formed between the first half ring 211 and the second half ring 212, and the two first connecting portions 230 are respectively connected to the two sides of the shielding portion 220. It should be noted that the curvature of the first half ring 211 and the second half ring 212 can both be 160 to 180 degrees, but are not limited thereto. For example, the curvature of the first half ring 211 is greater than 180 degrees and the curvature of the second half ring 212 is less than 180 degrees, as long as the window portion 210 formed by the two together can tin the connector pad and ensure tinning.

[0068] The first connecting portion 230 acts as a connecting rib on the printed steel mesh 200, so that the shielding portion 220 can be connected to the rest of the printed steel mesh 200; the first half ring 211 and the second half ring 212 are arranged at intervals. Since the solder paste 20 is fluid, during printing, the solder paste 20 leaked by the first half ring 211 and the second half ring 212 can flow to the position corresponding to the first connecting portion 230, so that the tin protective layer continuously covers the connector pad 10.

[0069] Furthermore, the window portion 210 further includes a third half ring 213 and a fourth half ring 214 opposite to each other, and two spaced second connection portions 240 are formed between the third half ring 213 and the fourth half ring 214, and the third half ring 213 and the fourth half ring 214 are arranged outside the first half ring 211 and the second half ring 212; the two first connection portions 230 and the two second connection portions 240 are alternately and spacedly arranged on the periphery of the shielding portion 220. In this way, the printing quality of the solder paste 20 can be improved, so that the tin protective layer completely covers the connector pad 10 to avoid copper exposure.

[0070] like Figure 4 , Figure 5As shown, the window portion 210 is a double-ring structure, and the inner and outer rings are staggered, that is, the circular ring where the first half ring 211 and the second half ring 212 are located is arranged inside the circular ring where the third half ring 213 and the fourth half ring 214 are located; the angle between the adjacent first connecting portion 230 and the second connecting portion 240 and the center of the window portion 210 can be 90 degrees, so that the thickness of the tin protective layer is more uniform.

[0071] Please refer to Figure 6 and Figure 7 Optionally, the window portion 210 may be a single ring structure, including a first half ring 211 and a second half ring 212 opposite to each other, with two spaced first connecting portions 230 formed between the first half ring 211 and the second half ring 212; wherein the end of the first half ring 211 protrudes toward the direction close to the shielding portion 220; and / or the end of the first half ring 211 protrudes toward the direction away from the shielding portion 220. In this way, the opening size of the ends of the first half ring 211 and the second half ring 212 can be increased to avoid insufficient solder paste 20 at the bridge to cover the connector pad 10.

[0072] Please refer to Figure 2 , Figure 8 In one embodiment, the connector 50 is soldered to the connector pad 10, including:

[0073] First, the pins of the connector 50 are inserted into the corresponding insertion holes 101 of the connector pads 10 .

[0074] Next, solder flux is sprayed onto the pins of the connector 50 and the connector pads 10 , and preheating is performed, wherein a heating tube or a heating plate can be used to preheat the flexible circuit board 100 .

[0075] Then, the position of the connector pad 10 is selectively wave soldered to melt the tin protective layer and form a wave-shaped extension pin, so as to fix the pin of the connector 50 to the connector pad 10. The nozzle in the tin furnace forms the molten solder paste 20 into a wave shape to connect with the pin of the connector 50, and the solder paste 20 is melted by the flux to expand and fill, and finally achieve the purpose of complete welding.

[0076] The above method uses selective wave soldering to solder the connector 50, which can achieve local welding of the connector 50. When the connector 50 is welded, it will not affect the nickel sheet 30 and the solder paste 20 at the NTC welding position, thereby preventing the nickel sheet 30 and the NTC welding position from being subjected to high temperature and causing secondary tin melting. By adopting selective wave soldering processing technology, only the welding position of the connector 50 is subjected to high-temperature tin melting, and other positions are at room temperature, which not only ensures that the nickel sheet 30 and the NTC welding position are not affected by high temperature, but also ensures that the connector pad 10 is fully welded.

[0077] Optionally, before inserting the pins of the connector 50 into the corresponding insertion holes 101 of the connector pad 10, the flexible circuit board 100 is placed on the welding carrier; after inserting the pins of the connector 50 into the corresponding insertion holes 101 of the connector pad 10, the connector 50 is fixed with a positioning block. In this way, the pins of the connector 50 can be prevented from loosening during welding and affecting the welding accuracy.

[0078] In one embodiment, when the flexible circuit board 100 is reflowed, a nitrogen reflow furnace is used to reflow the flexible circuit board 100. In this way, the soldering effect of the solder paste 20 at the pin position can be ensured.

[0079] The second aspect of the present application provides a flexible circuit board 100 , which is manufactured by the welding method of the connector 50 of the flexible circuit board 100 of the first aspect.

[0080] The flexible circuit board 100 may be a new energy battery flexible circuit board, and the welded connector 50 may be a DIP connector, but is not limited thereto.

[0081] The above-mentioned flexible circuit board 100 can first print solder paste 20, weld nickel sheet 30, attach protective film 40, and then weld connector 50. On the one hand, it can avoid welding nickel sheet 30 and connector 50 at the same time to affect the attachment of protective film 40. On the other hand, when welding nickel sheet 30, a tin protective layer is provided on connector pad 10. The tin protective layer can protect connector pad 10 and avoid oxidation of connector pad 10 and reduce welding performance. Therefore, the above-mentioned flexible circuit board 100 has a better connector welding effect and better quality.

[0082] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method for welding a flexible circuit board connector, characterized in that: include: A flexible circuit board is provided, wherein a connector pad is provided on the flexible circuit board, wherein the connector pad is an annular pad and a plug hole is provided in the middle of the annular pad; Printing solder paste on the surface of the flexible circuit board through a printed steel mesh, wherein part of the solder paste covers the connector pad as a tin protective layer, the tin protective layer covers the annular pad and avoids the plug hole, and the printed steel mesh is provided with a window portion and a shielding portion, the shielding portion corresponds to the plug hole, the window portion surrounds the circumference of the shielding portion and corresponds to the annular pad, and the window portion is a double-ring structure, and the inner and outer rings are staggered; Pasting a nickel sheet on the flexible circuit board; Reflow soldering is performed on the flexible circuit board to fix the nickel sheet on the flexible circuit board through solder paste; Laminating a protective film on the surface of the flexible circuit board, and performing pressing and baking; A connector is soldered onto the connector pad, wherein the tin protective layer on the connector pad melts during soldering.

2. The flexible circuit board connector welding method according to claim 1, characterized in that: Printing solder paste on the surface of the flexible circuit board includes: Providing a printed steel mesh, wherein the size of the shielding portion is greater than or equal to the size of the plug hole; Placing the printed steel mesh above the flexible circuit board; The solder paste is printed on the surface of the flexible circuit board through the printed steel mesh, and the solder paste is covered on the annular pad through the window portion to form the tin protective layer.

3. The method for soldering a flexible circuit board connector according to claim 2, wherein: The window portion includes a first half ring and a second half ring which are arranged opposite to each other and have the same radius, and two spaced first connecting portions are formed between the first half ring and the second half ring, and the two first connecting portions are respectively connected to two sides of the shielding portion.

4. The method for soldering a flexible circuit board connector according to claim 3, characterized in that: The window portion also includes a third half ring and a fourth half ring relative to each other, two spaced second connecting portions are formed between the third half ring and the fourth half ring, and the third half ring and the fourth half ring are arranged outside the first half ring and the second half ring; two first connecting portions and two second connecting portions are alternately and spaced apart on the periphery of the shielding portion.

5. The flexible circuit board connector welding method according to claim 3, characterized in that: The end of the first half ring protrudes toward a direction approaching the shielding portion; and / or the end of the first half ring protrudes toward a direction away from the shielding portion.

6. The method for soldering a flexible circuit board connector according to claim 2, wherein: Soldering a connector onto the connector pad includes: Inserting the pins of the connector into the corresponding plug holes of the connector pads; Spraying flux onto the pins of the connector and the connector pads, and preheating them; Selective wave soldering is performed on the position of the connector pad to melt the tin protective layer and form a wave-shaped extension pin, so as to fix the pin of the connector and solder it to the connector pad.

7. The flexible circuit board connector welding method according to claim 6, characterized in that: Before inserting the pins of the connector into the corresponding plug-in holes of the connector pad, the flexible circuit board is placed on a welding carrier; after inserting the pins of the connector into the corresponding plug-in holes of the connector pad, the connector is fixed using a positioning block.

8. The method for soldering a flexible circuit board connector according to any one of claims 1 to 7, characterized in that: When the flexible circuit board is subjected to reflow soldering, a nitrogen reflow furnace is used to perform reflow soldering on the flexible circuit board.

9. A flexible circuit board, characterized in that: The flexible circuit board connector is manufactured by the welding method according to any one of claims 1 to 8.

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