Method for improving welding reliability of surface-mount type diverter
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A shunt and SMD technology, applied in the field of improving the welding of SMD shunts, can solve the problem of unstable bubble rate, etc., and achieve the improvement of the bubble rate problem, the promotion of the reliability of the whole vehicle, and the optimization of the opening shape of the steel mesh. Effect
Pending Publication Date: 2021-09-14
上海丸旭电子科技有限公司
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[0006] Aiming at the deficiencies of the prior art, the present invention provides a method for improving the reliability of the soldering of the SMD shunt, which solves the problem of improving the welding reliability of the SMD shunt, and designs a method that does not change the layout of the PCB board and the process flow. Solve the technical problems of unstable air bubble rate and improve and reduce air bubble rate at the same time under the premise
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example 1
[0030] In step S3, the ratio of tin paste is prepared according to the metal content such that the proportion of Tin is set to 90%, the proportion of Silver is set to 1%, the proportion of Cooper is set to 1%, and the proportion of Flux is set to 8%.
example 2
[0032] In step S3, the proportion of solder paste prepared according to the metal content is set as 80% for Tin, 4.5% for Silver, 0.5% for Cooper, and 15% for Flux.
example 3
[0034] In step S3, the proportion of solder paste prepared according to the metal content is set as 85% for Tin, 3.5% for Silver, 0.5% for Cooper, and 11% for Flux.
[0035] In summary, the ratio of solder paste in Example 3 is the best.
[0036] Under the premise of not making changes to the design of PCB and shunt, through the optimization of the proportion of solder paste and the shape of the opening of the stencil, the problem of air bubble rate is effectively improved, and the influence of air bubble rate problem on soldering reliability is solved, and It also solves the influence of changes in the air bubble rate that may be caused by changes in other welding conditions, so that the air bubble rate can be stably controlled within a safe range, which has a greater impact on the welding reliability of the patch shunt and the reliability of the entire vehicle. great promotion.
[0037] It is an essential process to weld the SMD shunt through the reflow furnace. Bubbles are...
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Abstract
The invention belongs to the technical field of SMT and discloses a method for improving the welding reliability of a surface-mount type diverter. The method comprises the following steps of: S1, preparation before welding, specifically, placing the surface-mount type diverter in a reflow furnace, adjusting furnace temperature parameter settings, prolonging the time of a preheating zone of the reflow furnace, removing metal oxides of the surface-mount type diverter and gas generated by soldering flux before welding, and reducing bubbles generated in the welding process; S2, steel mesh design, specifically, designing bonding pads in the shape of an opening of the steel mesh, trepanning the opening of the steel mesh according to the size of 1: 1, and reserving gaps between the bonding pads; and S3, solder paste preparation,specifically, designing new solder paste proportions, and according to metal content preparation proportions, setting the proportion of tin to be 80%-90%, the proportion of silver to be 1%-5%, the proportion of cooper to be 0.1%-1%, and the proportion of flux to be 5%-15%. According to the method for improving the welding reliability of the surface-mount type diverter, by optimizing the proportion of the solder paste and optimizing the opening shape of the steel mesh, the bubble rate problem is effectively improved, and the influence of the bubble rate problem on the welding reliability is solved.
Description
technical field [0001] The invention relates to the technical field of SMT, in particular to a method for improving the reliability of patch type shunt welding. Background technique [0002] The shunt itself is a short conductor that can carry and measure a large DC current. It can be made of various metals or alloys, and its DC resistance is strictly adjusted; if it is connected in series in a DC circuit, the DC current is too shunted The two ends of the shunt generate a millivolt DC voltage signal, which makes the pointer of the meter connected to the two ends of the shunt swing, and the reading is the current value of the road. The so-called shunting means dividing a small current to drive the meter indication. The smaller the ratio of the small current (mA) to the current in the large circuit (1A-tens of A), the better and more accurate the reading line of the ammeter will be. [0003] The shunt needs to carry and output a large current, so the welding reliability of th...
Claims
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