High-precision integrated surface-mounted power resistor packaging and welding clamp

Abstract

The utility model discloses a high-precision integrated surface-mounted power resistor packaging and welding clamp, and belongs to the technical field of power resistor packaging. Comprising a clamp base body, a cooling fin positioning cavity, a resistor body positioning cavity, a lead-out pin positioning groove, a lead-out pin external welding section placing frame, a soldering flux discharging groove and a taking and placing groove. The front face of the clamp base body is a plane, and the cooling fin positioning cavity, the resistor body positioning cavity, the lead-out pin positioning groove, the lead-out pin external welding section placing frame, the scaling powder discharging groove and the taking and placing groove are integrally manufactured on the front face of the clamp base body. The radiating fin positioning cavity and the resistor body positioning cavity are the same cavity, the soldering flux discharging groove is formed in the radiating fin positioning cavity, the lead-out pin external welding section placing frame is communicated with the lead-out pin positioning groove, and the taking and placing grooves are formed in the two sides of the radiating fin positioning cavity. The problems that an existing power resistor is low in packaging and welding efficiency, poor in quality consistency, large in welding size deviation and low in welding yield are solved. The method is applied to the packaging and welding technology of the surface-mounted power resistor.

Description

Technical Field

[0001] This utility model belongs to the field of power resistor packaging technology, and more specifically to the field of surface-mount power resistor packaging technology. In particular, it relates to a high-precision integrated surface-mount power resistor packaging welding fixture. Background Technology

[0002] like Figure 1 As shown, the structure of a surface-mount power resistor includes leads 3 and 4, a heat sink 5, and a resistor element (composed of a resistor carrier 1 and a resistive film 2). The resistive film 2 is located in the center of the front side of the resistor carrier 1, the lead soldering areas are on both sides of the resistor carrier 1, and the soldering area for the heat sink 5 is on the back side of the resistor carrier 1. The resistor carrier 1 is mounted on the lower half of the heat sink 5. Currently, the main method for soldering the non-framed leads and copper sheet of this type of packaged resistor is vacuum eutectic furnace soldering. Specific soldering methods include separate step-by-step soldering and simplified integrated soldering. The separate step-by-step soldering process involves first soldering the leads using metal limiting fixtures, and then soldering the resistor element with the soldered leads onto the copper sheet. The simplified integrated soldering uses multi-layer assembled metal fixtures to simultaneously limit the positions of the leads and the heat sink copper sheet, and a single eutectic soldering welds the leads and the heat sink copper sheet to the corresponding positions of the resistor element. The disadvantages of step-by-step soldering are slow production efficiency, poor soldering quality consistency, and large dimensional deviations. The disadvantages of multi-layer assembled metal welding fixtures are that overflowing solder during the welding process can easily weld the product and the metal fixture together, leading to severe product damage during removal and a low yield. Furthermore, multi-layer metal fixtures are heavy and have relatively slow heat conduction, resulting in longer waiting times when changing products during production and overall low efficiency. Therefore, this utility model is proposed. Summary of the Invention

[0003] The technical problem to be solved by this utility model is to address the issues of low welding efficiency, poor welding quality consistency, large welding size deviation, and low welding yield of existing surface-mount power resistors.

[0004] The inventive concept of this utility model is: based on the shape, structure and related dimensions of the surface-mount power resistor, to integrally fabricate the heat dissipation copper sheet and the positioning groove of the lead end of the fixed resistor on the surface of the graphite block.

[0005] Therefore, this utility model provides a high-precision integrated surface-mount power resistor packaging and welding fixture, such as... Figure 1-3 As shown, it includes a fixture base body 6, a heat sink positioning cavity 7, a resistor positioning cavity 8, a lead positioning groove 9, a lead external welding section placement frame 10, a flux discharge groove 11, and a pick-and-place groove 12.

[0006] The front of the fixture base body 6 is flat.

[0007] The heat sink positioning cavity 7, resistor positioning cavity 8, lead-out pin positioning groove 9, lead-out pin external welding section placement frame 10, flux discharge groove 11 and pick-and-place groove 12 are integrally fabricated on the front of the fixture base body 6.

[0008] The heat sink positioning cavity 7 and the resistor positioning cavity 8 are the same cavity. The cavity depth is greater than or equal to the thickness of the heat sink 5 plus the thickness of the resistor. The longitudinal dimension of the cavity is slightly larger than the longitudinal dimension of the heat sink 5, and the transverse dimension of the cavity is slightly larger than the transverse dimension of the heat sink 5.

[0009] The flux discharge groove 11 is located on one side of the heat sink positioning cavity 7 and the resistor positioning cavity 8 along the lead direction, and is made inside the heat sink positioning cavity 7 and the resistor positioning cavity 8. The depth, width and length of the flux discharge groove 11 are determined by setting.

[0010] The lead-out positioning groove 9 is located on one side of the heat sink positioning cavity 7 and the resistor positioning cavity 8 along the lead-out direction. The depth, width and length of the lead-out positioning groove 9 are determined by the root size of the lead-out.

[0011] The lead-out foot external welding section placement frame 10 is connected to the lead-out foot positioning groove 9. The depth of the lead-out foot external welding section placement frame 10 is determined by the size of the lead-out foot bending part. The length of the lead-out foot external welding section placement frame 10 is determined by the size of the horizontal end of the lead-out foot tail. The width of the lead-out foot external welding section placement frame 10 is determined by the size and spacing of the two lead-out feet.

[0012] The pick-and-place slot 12 is located on both sides of the upper and lower edges of the heat sink positioning cavity 7 and the resistor positioning cavity 8, and is in communication with the heat sink positioning cavity 7 and the resistor positioning cavity 8. The depth of the pick-and-place slot 12 is greater than or equal to the depth of the positioning cavity 7, and the width and length of the pick-and-place slot (12) are determined by setting.

[0013] This utility model welding fixture is lightweight, has fast heat transfer during welding, and reduces the time spent replacing resistors after welding. It achieves high-precision, high-reliability integrated welding. It features fast heat conduction during welding, small dimensional deviations after welding, and high welding accuracy. The welded product does not adhere to the solder, resulting in good quality consistency, high yield, and high efficiency.

[0014] It can be widely used in surface-mount power resistor packaging and soldering technology. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the internal structure of a power resistor. Figure 1 'a' is the front view. Figure 1 b is a side view.

[0016] Figure 2 This is a schematic diagram of the welding fixture structure of this utility model.

[0017] Figure 3 This is a three-dimensional structural diagram of the product into which the welding fixture of this utility model is installed.

[0018] In the figure: 1 is the resistor carrier, 2 is the resistor film, 3 is the first lead, 4 is the second lead, 5 is the heat sink, 6 is the fixture base body, 7 is the heat sink positioning cavity, 8 is the resistor positioning cavity, 9 is the lead positioning groove, 10 is the lead external welding section placement frame, 11 is the flux discharge groove, and 12 is the pick-and-place groove. Detailed Implementation

[0019] like Figure 1-3 As shown, the high-precision integrated surface-mount power resistor packaging and welding fixture, taking the T0252 type plastic packaged power resistor welding fixture from China Zhenhua Group Yunke Electronics Co., Ltd. as an example, is specifically implemented as follows:

[0020] The fixture base body 6 is a cuboid made of graphite.

[0021] The heat sink 5 has a square portion for mounting the resistor carrier 1, and a trapezoidal portion extending beyond the resistor carrier 1. The material is copper.

[0022] The welding stations for the power resistors are arranged in rows or columns, with at least one row or column and at least two stations in each row or column. In each row, the heat sink positioning cavity 7 and the resistor positioning cavity 8 are fully connected, the lead-out external welding section placement frame 10 is fully connected, the flux discharge groove 11 is fully connected, and the pick-and-place groove 12 of adjacent stations is fully connected.

[0023] Specifically, the heat sink positioning cavity 7 is a frame groove that limits the copper sheet and resistor. The length and width of the heat sink positioning cavity 7 are the length and width of the copper sheet plus 0.1mm, and the depth is the sum of the thickness of the heat sink, the resistor, and the lead-out end. The flux discharge groove 11, located near the edge of the resistor, is 1mm wide and 1mm deep. This is to increase flux discharge during welding, extend the service life of the welding fixture, and reduce cleaning frequency. The lead-out foot positioning groove 9 is the left and right limiting area for the lead-out ends, designed according to the lead-out end spacing and width. The pick-and-place groove 12 is a recessed area for easy pick-and-place of the copper sheet, resistor, and welded finished product. Other locations are connected to facilitate fixture fabrication, reducing the difficulty of fixture processing.

[0024] This utility model takes into account the welding space of the welding equipment and the frequency of manual cross-operations, and designs the layout as two rows and five columns. One fixture can hold 10 products, and one welding operation can hold 10 fixtures and 100 products. The specific design can be adjusted according to the size of the welding equipment space and the operation process.

[0025] Furthermore, the depth of the heat sink positioning cavity 7 is less than or equal to the depth of the pick-and-place slot 12, thereby limiting the heat sink (copper sheet) 5 and the resistor body around its perimeter.

[0026] The specific welding process and fixture usage are as follows:

[0027] (1) Place the copper sheet in the heat sink positioning cavity 7. The upper and lower ends of the heat sink positioning cavity 7 will limit the copper sheet. Then, apply solder paste to the welding area on the surface of the copper sheet. The flux discharge groove 11 is a groove for discharging solder solvent.

[0028] (2) Place the back-metallized resistor on the copper sheet and apply solder paste to the two terminals of the resistor.

[0029] (3) Place the lead end on the electrode tip of the resistor body and use the lead foot positioning groove 9 for left and right positioning to ensure the width spacing of the lead after welding. At the same time, the limiting effect of the upper end of the heat sink positioning cavity 7 and the lower end of the lead foot external welding section placement frame 10 in the length direction ensures the final length dimension of the resistor.

[0030] (4) Place the fixture and the product together in the eutectic furnace and complete the eutectic welding according to the set welding curve.

[0031] (5) After welding is completed, simply reverse the fixture and the product can be removed.

[0032] To address the issues of slow heat conduction, large dimensional deviations after welding, product adhesion to solder, low yield, and low efficiency associated with multi-layer metal welding fixtures, a high-precision, integrated welding fixture made of graphite has been developed. This fixture offers high welding accuracy and good consistency. Furthermore, it is lightweight, allows for rapid heat transfer during welding, minimizes product replacement time after welding, and significantly increases efficiency.

[0033] Finally, it should be noted that the above embodiments are merely examples for clear illustration. This utility model includes, but is not limited to, the above embodiments, and it is neither necessary nor possible to exhaustively describe all implementation methods. Those skilled in the art can make other variations or modifications based on the above description. All implementation schemes that meet the requirements of this utility model are within the protection scope of this utility model.

Claims

1. A high-precision integrated surface-mount power resistor packaging and welding fixture, characterized in that: It includes a fixture base body (6), a heat sink positioning cavity (7), a resistor positioning cavity (8), a lead positioning groove (9), a lead external welding section placement frame (10), a flux discharge groove (11), and a pick-and-place groove (12). The front of the fixture base body (6) is flat; The heat sink positioning cavity (7), resistor positioning cavity (8), lead-out pin positioning groove (9), lead-out pin external welding section placement frame (10), flux discharge groove (11) and pick-and-place groove (12) are integrally fabricated on the front side of the fixture base body (6); The heat sink positioning cavity (7) and the resistor positioning cavity (8) are the same cavity. The cavity depth is greater than or equal to the thickness of the heat sink (5) plus the thickness of the resistor carrier (1). The longitudinal dimension of the cavity is slightly larger than the longitudinal dimension of the heat sink (5), and the transverse dimension of the cavity is slightly larger than the transverse dimension of the heat sink (5). The flux discharge groove (11) is located on one side of the heat sink positioning cavity (7) and the resistor positioning cavity (8) along the lead direction, and is made inside the heat sink positioning cavity (7) and the resistor positioning cavity (8). The depth, width and length of the flux discharge groove (11) are determined by setting. The lead-out positioning groove (9) is located on one side of the heat sink positioning cavity (7) and resistor positioning cavity (8) along the lead-out direction. The depth, width and length of the lead-out positioning groove (9) are determined by the root size of the lead-out. The lead-out foot external welding section placement frame (10) is connected to the lead-out foot positioning groove (9). The depth of the lead-out foot external welding section placement frame (10) is determined by the size of the lead-out foot bending part. The length of the lead-out foot external welding section placement frame (10) is determined by the size of the horizontal end of the lead-out foot tail. The width of the lead-out foot external welding section placement frame (10) is determined by the size and spacing of the two lead-out feet. The pick-and-place slot (12) is located on both sides of the upper and lower edges of the heat sink positioning cavity (7) and the resistor positioning cavity (8), and is in communication with the heat sink positioning cavity (7) and the resistor positioning cavity (8). The depth of the pick-and-place slot (12) should be greater than or equal to the depth of the positioning cavity (7). The width and length of the pick-and-place slot (12) are determined by setting.

2. The high-precision integrated surface-mount power resistor packaging and welding fixture as described in claim 1, characterized in that: The heat sink (5) has a square part where the resistor carrier (1) is attached, and a trapezoidal part that extends beyond the resistor carrier (1). The material is copper.

3. The high-precision integrated surface-mount power resistor packaging and welding fixture as described in claim 1, characterized in that: The fixture base body (6) is a cuboid.

4. The high-precision integrated surface-mount power resistor packaging and welding fixture as described in claim 1, characterized in that: The length and width of the heat sink positioning cavity (7) are the length and width of the heat sink plus 0.1mm, and the depth is the sum of the thickness of the heat sink, the thickness of the resistor, and the thickness of the lead-out end.

5. The high-precision integrated surface-mount power resistor packaging and welding fixture as described in claim 1, characterized in that: The flux discharge groove (11) is 1 mm wide and 1 mm deep.

6. The high-precision integrated surface-mount power resistor packaging and welding fixture as described in claim 1, characterized in that: The welding stations of the power resistors are arranged in rows or columns, with at least one row or column and at least two stations in each row or column; the heat sink positioning cavity (7) and resistor positioning cavity (8) of all stations in each row are fully connected, the lead-out external welding section placement frame (10) is fully connected, the flux discharge groove (11) is fully connected, and the pick-and-place groove (12) of adjacent stations is fully connected.

7. The high-precision integrated surface-mount power resistor packaging and welding fixture as described in claim 6, characterized in that: The workstation is arranged in 2 rows and 5 columns.

8. The high-precision integrated surface-mount power resistor packaging and welding fixture as described in claim 1, characterized in that: The depth of the heat sink positioning cavity (7) is less than or equal to the depth of the pick-and-place slot (12).

9. The high-precision integrated surface-mount power resistor packaging and welding fixture as described in claim 1, characterized in that: The heat sink (5) is a copper heat sink.

10. A high-precision integrated surface-mount power resistor packaging and welding fixture as described in claim 1, characterized in that: The fixture base body (6) is a graphite fixture base.

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