Pad structure

Abstract

The utility model provides a bonding pad structure, comprising a printed circuit board which comprises a main body part, a bonding pad part and a lug hole; a plurality of electronic components can be mounted in the main body part; tabs of the battery cell penetrate through the tab holes and are overlapped with the bonding pad parts; and a first groove is formed between the bonding pad part and the electronic component. According to the utility model, the groove is formed in the pad part of the tab of the battery cell, so that tin beads or tin bars generated by the tab during laser welding can overflow into the groove, and the tin beads or tin bars generated during the welding process of the tab in the soft package battery cell can be prevented from overflowing out of the pad or an electrode plate, thereby ensuring the safety performance of a printed circuit board.

Description

Technical Field

[0001] The present application relates to the fields of circuit board manufacturing and lithium battery manufacturing, and in particular to a solder pad structure. Background Art

[0002] In the new energy industry, lithium batteries are increasingly being used in various fields due to their safety, high energy density, and long cycle life. Laser welding is a common method for welding tabs in lithium batteries. This method utilizes localized heating of the weld joint, forming and solidifying a molten pool to connect the electrode tab and achieve a good overlap between the tab and the electrode.

[0003] However, in the existing technology, before the battery tabs are laser welded, the electrode sheets are completely fitted to the electrode pads on the corresponding circuits, and the electrode sheets are firmly adhered to the corresponding pads through the wave soldering process. However, when the battery tabs and the electrode sheets are laser welded, instantaneous high temperature is generated during the laser welding process and heat is conducted to the electrode pads through the electrode sheets. When the melting point of the tin in the printed circuit board is reached, round tin beads or tin slag are generated in the printed circuit. The round tin beads or tin slag are easily attached to the electrode sheets or overflow from the electrode pads and roll and adhere to other electronic devices in the printed circuit board. Since the round tin beads or tin slag are conductive, there is a risk of short-circuiting other electronic devices installed on the printed circuit board, which may seriously cause the soft-pack lithium battery to short-circuit and catch fire. Utility Model Content

[0004] In order to solve the problem in the prior art that tin beads or tin slag generated during the soldering process between the battery cell tab and the printed circuit board can easily cause short circuits in electronic components or the printed circuit board, the utility model provides a solder pad structure, comprising: a printed circuit board, the printed circuit board including a main body, a solder pad portion, and a tab hole; a plurality of electronic components can be mounted in the main body; the battery cell tab passes through the tab hole and overlaps the solder pad portion; and a first groove is provided between the solder pad portion and the electronic component.

[0005] Furthermore, a second groove is provided between the tab hole and the pad portion.

[0006] Furthermore, the depth of the first groove is greater than the depth of the second groove.

[0007] Furthermore, the width of the first groove is equal to the width of the second groove.

[0008] Furthermore, a plurality of first grooves and second grooves are provided on the printed circuit board.

[0009] Furthermore, the first groove is configured as an inverted trapezoid.

[0010] Furthermore, the first groove has a depth greater than or equal to 1 mm and a width greater than or equal to 1 mm.

[0011] Furthermore, an electrode sheet is provided between the pad portion and the tab. The tab pad portion of the battery cell of the present invention is provided with a groove, which allows tin beads or tin bars generated during laser welding of the tab to overflow into the groove. This can prevent tin beads or tin bars generated during the tab welding process in the soft-pack battery cell from overflowing from the pad or electrode sheet, thereby ensuring safety performance in the printed circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of the power pad structure and electronic components of the utility model. DETAILED DESCRIPTION

[0013] 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0014] like Figure 1 As shown, the pad structure in the embodiment of the present invention includes a printed circuit board 10. Specifically, the printed circuit board 10 includes a main body 101, a pad portion 102, and a tab hole 103; multiple electronic components 104 are installed in the main body 101; the tabs 20 of the battery cell pass through the tab holes 103 and overlap with the pad portion 102; a first groove 301 is provided between the pad portion 102 and the electronic component 104; and a second groove 302 is further provided between the tab hole 103 and the pad portion 102. In this embodiment, in the printed circuit board with the pad structure, multiple first grooves 301 and second grooves 302 can be provided to accommodate the soldering of tabs of multiple battery cells to the printed circuit board.

[0015] Specifically, the pad structure and the welding to the battery tab in the embodiment of the present invention are mainly carried out according to the following steps: The printed circuit board in this embodiment is made of FR-4 epoxy resin. To ensure the mechanical strength and other performance of the printed circuit board, the thickness of the printed circuit board is preferably 1.6 mm. The printed circuit board is formed into a multi-layer structure. At the same time, the top layer of the printed circuit board is provided with a pad portion 102. A plurality of electronic components 104 can be mounted on the top layer of the main body portion 101 of the printed circuit board and can be electrically connected to the printed circuit board by welding, plugging, etc. to facilitate the connection.

[0016] The tabs 20 in the battery are welded to the printed circuit board according to the following steps: before welding, the printed circuit board 10 is fixed with a mold, and then the tabs 20 of the battery cell are passed through the tab holes 103 on the printed circuit board and extended from the bottom end to the top end of the printed circuit board and the tabs are bent; so that the tabs overlap with the pad portion 101, thereby achieving the bonding of the battery cell tabs and the electrode sheets, and then laser alignment and welding are performed.

[0017] like Figure 1A rectangular pad portion 102 is provided on the printed circuit board. The size of the pad portion 102 is substantially the same as that of the electrode sheet 40. The pad portion is not grooved inside or on its surface. Instead, a first groove 301 is dug on one side of the pad portion of the printed circuit board, i.e., the side close to the electronic components. The depth of the first groove 301 is greater than or equal to 1 mm, and the width of the first groove 301 is greater than or equal to 1 mm. A second groove 302 is dug on the other side of the pad portion of the printed circuit board. The depth of the second groove 302 is set to be greater than or equal to 0.5 mm, and the width of the second groove 302 is set to be greater than or equal to 1 mm. When the electrode sheet 40 needs to be installed on the pad portion 102, solder paste is first applied to the pad portion 102. However, the first groove 301 and the second groove 302 provided near the pad portion 102 are not applied. Then, the electrode sheet 40 is attached to the soldered pad portion. In this embodiment, the size of the electrode sheet 40 is preferably set to be substantially equal to that of the pad portion 102. After the patch process is completed, the electrode sheet 40 on the printed circuit board and the tab 20 on the soft-pack lithium battery need to be laser welded. During welding, due to the high temperature of the electrode sheet 40 melting the tin on the bottom pad during the laser welding process, the melted tin will produce tin beads or tin bars, and will overflow outside the pad part; at this time, a first groove 301 and a second groove 302 are provided on both sides of the pad part 102, and the tin beads or tin bars overflowing during the welding process will be accommodated by the first groove 301 and the second groove 302 outside the pad part; thereby, the tin beads or tin bars at the bottom of the electrode sheet 40 can be prevented from being discharged outside the pad part 102 and contacting the electronic components 104 attached to the pad part, thereby avoiding the risk of short circuit caused by the contact between the tin beads or tin bars and the electronic components, and also avoiding the short circuit or open circuit caused by the tin beads or tin bars generated during the welding process contacting the circuit on the top layer of the printed circuit board. In this embodiment, the first groove 301 and the second groove 302 are constructed as blind holes with one end open and the other end closed. This configuration can prevent the tin beads melted from the bottom pad of the electrode from overflowing from the printed circuit board. Furthermore, the groove depth of the first groove is greater than the groove depth of the second groove on the side close to the more electronic components, so as to accommodate more tin beads and tin bars, reduce overflow onto the electronic components, and further improve the safety performance of the printed circuit board. At the same time, in order to better receive and accommodate the tin beads and tin bars generated during the welding process, the shape of the second groove is also constructed as an inverted trapezoid with a large upper end and a small lower end. The large opening at the upper end can better receive the tin beads and tin bars generated during the welding process.

[0018] In the present invention, grooves are provided on both sides of the battery cell tab pad portion. Such a pad structure setting can allow the tin beads or tin bars generated by laser welding to overflow into the grooves, thereby preventing the tin beads or tin bars generated during the tab welding process in the soft-pack battery cell from overflowing from the pad or electrode sheet, thereby ensuring the safety performance in the printed circuit board.

[0019] The above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the implementation methods of the present invention. A person skilled in the art will be able to make other variations or modifications based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A pad structure, comprising: A printed circuit board, comprising a main body, a pad portion, and tab holes; a plurality of electronic components can be mounted in the main body; The tab of the battery cell passes through the tab hole and overlaps with the pad portion; it is characterized in that a first groove is provided between the pad portion and the electronic component.

2. The pad structure according to claim 1, wherein: A second groove is provided between the tab hole and the pad portion.

3. The pad structure according to claim 2, wherein: The depth of the first groove is greater than the depth of the second groove.

4. The pad structure according to claim 3, wherein: The width of the first groove is equal to the width of the second groove.

5. The pad structure according to claim 4, wherein: The printed circuit board is provided with a plurality of first grooves and a second groove.

6. The pad structure according to claim 3, wherein: The first groove is configured as an inverted trapezoid.

7. The pad structure according to claim 3, wherein: The first groove has a depth greater than or equal to 1 mm and a width greater than or equal to 1 mm.

8. The pad structure according to claim 3, wherein: An electrode sheet is provided between the pad portion and the tab.

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