CN113395840A - Method for improving welding reliability of surface mount type shunt - Google Patents
Method for improving welding reliability of surface mount type shunt Download PDFInfo
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- CN113395840A CN113395840A CN202110619556.9A CN202110619556A CN113395840A CN 113395840 A CN113395840 A CN 113395840A CN 202110619556 A CN202110619556 A CN 202110619556A CN 113395840 A CN113395840 A CN 113395840A
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- 238000003466 welding Methods 0.000 title claims abstract description 57
- 238000000034 method Methods 0.000 title claims abstract description 40
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 25
- 239000010959 steel Substances 0.000 claims abstract description 25
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 20
- 230000004907 flux Effects 0.000 claims abstract description 18
- 230000008569 process Effects 0.000 claims abstract description 17
- 229910000679 solder Inorganic materials 0.000 claims abstract description 16
- 229910052751 metal Inorganic materials 0.000 claims abstract description 13
- 239000002184 metal Substances 0.000 claims abstract description 13
- 229910052709 silver Inorganic materials 0.000 claims abstract description 13
- 239000004332 silver Substances 0.000 claims abstract description 13
- 238000002360 preparation method Methods 0.000 claims abstract description 10
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 5
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 5
- 238000005476 soldering Methods 0.000 claims abstract description 5
- 238000000746 purification Methods 0.000 claims description 10
- 238000005457 optimization Methods 0.000 abstract description 4
- 230000008859 change Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 239000011148 porous material Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000006071 cream Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Electric Connection Of Electric Components To Printed Circuits (AREA)
Abstract
The invention relates to the technical field of SMT, and discloses a method for improving the welding reliability of a surface mount type shunt, which comprises the following steps: s1, preparation before welding: placing the surface mount type shunt in a reflow furnace, adjusting the furnace temperature parameter setting, prolonging the time of a preheating area of the reflow furnace, removing metal oxides of the surface mount type shunt and gas generated by soldering flux before welding, and reducing the generation of bubbles in the welding process; s2, designing a steel net: designing a bonding pad in the shape of an opening of a steel mesh, wherein the opening of the steel mesh is provided with holes according to the ratio of 1:1, and gaps are reserved among the bonding pads; s3, proportioning solder paste: designing a new solder paste proportion, wherein the proportion of Tin is set to be 80-90%, the proportion of Silver is set to be 1-5%, the proportion of Cooper is set to be 0.1-1%, and the proportion of Flux is set to be 5-15% according to the metal content preparation proportion. According to the method for improving the welding reliability of the surface mount type shunt, the problem of bubble rate is effectively improved through the optimization of the proportion of the solder paste and the optimization of the shape of the opening of the steel mesh, and the influence of the problem of bubble rate on the welding reliability is solved.
Description
Technical Field
The invention relates to the technical field of SMT, in particular to a method for improving the welding reliability of a surface mount type shunt.
Background
The shunt is a short conductor, can bear and measure a large direct current, can be made of various metals or alloys, and has the direct current resistance which is strictly adjusted; the direct current flows through the shunt, millivolt direct current voltage signals are generated at two ends of the shunt, meter pointers connected in parallel at two ends of the shunt swing, and the reading is the current value in the direct current circuit. So-called shunting, i.e. dividing a small current to push the meter to indicate, the smaller the proportion of the small current (mA) to the current in the large loop (1A-tens of a), the better and more accurate the line of the current meter indicating the reading.
The shunt needs to carry and output a large current, and the requirement on the welding reliability of the shunt is high, which means that the bubble rate which is the most important factor influencing the welding reliability is managed by the requirement in the welding process. In the process flow of the surface mount type shunt, the welding conditions can not be selected, and the problem of bubble generation in the welding process is difficult to avoid due to the fact that impurities or oxides exist in elements and welding materials in the SMT reflow welding process. The bubble rate of the flow divider is generally controlled by setting a furnace temperature curve of the reflow furnace, but the control method cannot effectively prevent the generation of bubbles, and the change of the bubble rate is large due to the change of other factors, so that the problem of the bubble rate cannot be strictly controlled. Too much air bubbles may affect the welding reliability, thereby having a great influence on the safety of the battery pack.
At present, the welding of current SMD shunt has following problem: in the welding process, bubbles cannot be avoided, only the furnace temperature curve is controlled, when other interference factors are changed, the bubble rate is also changed, when the welding shunt has more bubbles, the reliability is poor, large current cannot be continuously and stably output, and when the shunt falls off from a substrate due to poor welding reliability and factors such as vibration and temperature and humidity change brought by a new energy automobile application environment, the safety problem of a battery pack can be caused; because the new energy automobile battery package needs to bear and output a large amount of current, if the problem of shunt welding reliability is not solved, the reliability of the new energy automobile battery package parts and the reliability of the whole automobile are affected very adversely. For this reason, a corresponding technical scheme needs to be designed for solution.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a method for improving the welding reliability of a surface mount type shunt, which solves the technical problems of improving the welding reliability of the surface mount type shunt, and simultaneously solving the instability of the bubble rate and improving the bubble rate reduction on the premise of not changing the layout and the process flow of a PCB (printed circuit board).
(II) technical scheme
In order to achieve the purpose, the invention is realized by the following technical scheme: a method for improving the welding reliability of a surface mount type shunt comprises the following steps:
s1, preparation before welding: placing the surface mount type shunt in a reflow furnace, adjusting the furnace temperature parameter setting, prolonging the time of a preheating area of the reflow furnace, removing metal oxides of the surface mount type shunt and gas generated by soldering flux before welding, and reducing the generation of bubbles in the welding process;
s2, designing a steel net: designing a bonding pad in the shape of an opening of a steel mesh, wherein the opening of the steel mesh is provided with holes according to the ratio of 1:1, and gaps are reserved among the bonding pads;
s3, proportioning solder paste: designing a new solder paste proportion, wherein the proportion of Tin is set to be 80-90%, the proportion of Silver is set to be 1-5%, the proportion of Cooper is set to be 0.1-1%, and the proportion of Flux is set to be 5-15% according to the metal content preparation proportion.
Preferably, in step S1, a purification fan is installed at a side of the reflow oven, an air suction port is arranged at a front end of the purification fan, and a filter screen is installed inside the purification fan.
Preferably, in step S2, the pad is a ladder steel mesh, and the steel mesh opening thickness of the pad is different from that of other components.
Preferably, in step S3, the ratio of Tin paste is set to 90% in proportion to Tin, 1% in proportion to Silver, 1% in proportion to Cooper, and 8% in proportion to Flux.
Preferably, in step S3, the ratio of Tin paste is 80% in the metal content, 4.5% in Silver, 0.5% in Cooper, and 15% in Flux.
Preferably, in step S3, the ratio of Tin paste is 85% in the metal content, 3.5% in Silver, 0.5% in Cooper, and 11% in Flux.
(III) advantageous effects
The method for improving the welding reliability of the surface mount type shunt can effectively improve the bubble rate problem by optimizing the proportion of solder paste and the shape of an opening of a steel mesh on the premise of not changing the design of a PCB and the shunt, solves the influence of the bubble rate problem on the welding reliability, and also solves the influence of the change of the bubble rate possibly caused by the change of other welding conditions, so that the bubble rate can be stably controlled in a safe range, and has great promotion significance on the welding reliability of the surface mount type shunt and the reliability improvement of the whole vehicle.
Drawings
FIG. 1 is a schematic top view of the shape of the opening of the steel net according to the present invention to solve the problem of improving the bubble rate;
FIG. 2 is a schematic cross-sectional view illustrating the shape of the opening of the steel net according to the present invention to solve the problem of improving the bubble rate;
FIG. 3 is a schematic view of solder paste dispensing ratio data for solving the problem of improving the bubble ratio according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-3, an embodiment of the present invention provides a technical solution: a method for improving the welding reliability of a surface mount type shunt comprises the following steps:
s1, preparation before welding: placing the surface mount type shunt in a reflow furnace, adjusting the furnace temperature parameter setting, prolonging the time of a preheating area of the reflow furnace, removing metal oxides of the surface mount type shunt and gas generated by soldering flux before welding, and reducing the generation of bubbles in the welding process;
s2, designing a steel net: designing a bonding pad in the shape of an opening of a steel mesh, wherein the opening of the steel mesh is provided with holes according to the ratio of 1:1, and gaps are reserved among the bonding pads;
s3, proportioning solder paste: designing a new solder paste proportion, wherein the proportion of Tin is set to be 80-90%, the proportion of Silver is set to be 1-5%, the proportion of Cooper is set to be 0.1-1%, and the proportion of Flux is set to be 5-15% according to the metal content preparation proportion.
In a further improvement, in step S1, a purification fan is installed at a side of the reflow oven, an air suction opening is arranged at a front end of the purification fan, and a filter screen is installed inside the purification fan, so that the purification and filtration of the gas generated by the metal oxide and the soldering flux of the patch type shunt are facilitated.
In a further improvement, in step S2, the pad is a stepped steel mesh, and the thickness of the steel mesh opening of the pad is different from that of other components, so as to avoid the problem of bubble rate caused by the fact that the pad cannot be completely filled with tin.
Example 1
In step S3, the ratio of Tin paste is prepared according to the metal content, where Tin is 90%, Silver is 1%, Cooper is 1%, and Flux is 8%.
Example 2
In step S3, the ratio of Tin paste is prepared according to the metal content, where Tin is 80%, Silver is 4.5%, Cooper is 0.5%, and Flux is 15%.
Example 3
In step S3, the ratio of Tin paste is set to 85%, the ratio of Silver is set to 3.5%, the ratio of Cooper is set to 0.5%, and the ratio of Flux is set to 11% in the metal content preparation.
In summary, the solder paste ratio of example 3 was used as best.
Under the prerequisite that can not make the change to the design of PCB and shunt, through the ratio optimization to the tin cream, steel mesh opening shape optimization, the effectual bubble rate problem that has improved, solve the influence of bubble rate problem to welding reliability, and also solved probably because the change of other welding conditions, and cause the influence that the bubble rate changes, the management and control that makes the bubble rate can be stable is in a safe within range, to SMD shunt welding reliability, whole car reliability promotion has great promotion meaning.
The surface mount type shunt is an indispensable procedure through reflow oven welding, bubbles are inevitably generated in the reflow oven welding shunt process, the quantity of the bubbles and the stability of the bubbles are directly in a linear relation with the welding reliability, and the welding reliability problem is directly related to the reliability of the whole vehicle.
According to the invention, through designing the shape of the opening of the steel mesh, gas is conveniently discharged in the gas welding process, and designing a novel solder paste proportion, the activity of the solder paste is enhanced, the porosity is ultralow, the pore size of the element with a large contact area is reduced, the welding reliability of the shunt is obviously improved, the breakthrough of the bubble rate technology of the patch type shunt is realized, and the safety problem caused by the welding reliability of the patch type shunt is solved.
According to the scheme, the shape of the start of the steel mesh shaped like the Chinese character 'tian' is designed, the welding quality requirement in the SMT process is guaranteed, holes are formed in the mesh opening according to the ratio of 1:1, gaps are reserved among the small welding pads, gas can be discharged in the welding process, and the problem of bubble rate caused by the fact that gas cannot be discharged in the welding process is solved.
The novel solder paste proportion is designed, the activity of the solder paste is increased, the ultralow porosity and the pore size of the element with the large contact area are reduced, the influence of other factors on the bubble rate in the welding process can be reduced, and the bubbles can be stably kept in a safe range.
The design of this scheme can realize that the shunt accomplishes the paster welding in SMT technology section, guarantees the problem of shunt welding reliability, ensures that the shunt can be continuously stable bear and export the high current, even under the abominable condition of operational environment, also can normal work.
The novel process is designed on the premise that the original product is unchanged in design, the reliability and safety of the product are improved, the scheme is simple and reliable, and the method is easy to realize and popularize in mass production.
While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (6)
1. A method for improving the reliability of welding of a surface mount type shunt is characterized by comprising the following steps:
s1, preparation before welding: placing the surface mount type shunt in a reflow furnace, adjusting the furnace temperature parameter setting, prolonging the time of a preheating area of the reflow furnace, removing metal oxides of the surface mount type shunt and gas generated by soldering flux before welding, and reducing the generation of bubbles in the welding process;
s2, designing a steel net: designing a bonding pad in the shape of an opening of a steel mesh, wherein the opening of the steel mesh is provided with holes according to the ratio of 1:1, and gaps are reserved among the bonding pads;
s3, proportioning solder paste: designing a new solder paste proportion, wherein the proportion of Tin is set to be 80-90%, the proportion of Silver is set to be 1-5%, the proportion of Cooper is set to be 0.1-1%, and the proportion of Flux is set to be 5-15% according to the metal content preparation proportion.
2. The method of claim 1, wherein the method comprises: in the step S1, a purification fan is installed on the side portion of the reflow oven, an air suction opening is formed in the front end of the purification fan, and a filter screen is installed inside the purification fan.
3. The method of claim 1, wherein the method comprises: in step S2, the bonding pad is a stepped steel mesh, and the thickness of the opening of the steel mesh of the bonding pad is different from that of other components.
4. The method of claim 1, wherein the method comprises: in step S3, the ratio of Tin paste is prepared according to the metal content, where Tin is 90%, Silver is 1%, Cooper is 1%, and Flux is 8%.
5. The method of claim 1, wherein the method comprises: in step S3, the ratio of Tin paste is prepared according to the metal content, where Tin is 80%, Silver is 4.5%, Cooper is 0.5%, and Flux is 15%.
6. The method of claim 1, wherein the method comprises: in step S3, the ratio of Tin paste is set to 85%, the ratio of Silver is set to 3.5%, the ratio of Cooper is set to 0.5%, and the ratio of Flux is set to 11% in the metal content preparation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110619556.9A CN113395840A (en) | 2021-06-03 | 2021-06-03 | Method for improving welding reliability of surface mount type shunt |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110619556.9A CN113395840A (en) | 2021-06-03 | 2021-06-03 | Method for improving welding reliability of surface mount type shunt |
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| Publication Number | Publication Date |
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| CN113395840A true CN113395840A (en) | 2021-09-14 |
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| CN202110619556.9A Pending CN113395840A (en) | 2021-06-03 | 2021-06-03 | Method for improving welding reliability of surface mount type shunt |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05291314A (en) * | 1992-04-10 | 1993-11-05 | Fujitsu General Ltd | Soldering of bare chip |
| CN101072886A (en) * | 2003-11-06 | 2007-11-14 | 铟美国公司 | Anti-tombstoning lead free alloys for surface mount reflow soldering |
| CN101925262A (en) * | 2010-08-02 | 2010-12-22 | 深圳和而泰智能控制股份有限公司 | Steel mesh and PCB (Printed Circuit Board) |
| CN102166689A (en) * | 2011-03-30 | 2011-08-31 | 浙江强力焊锡材料有限公司 | Halogen-free lead-free soldering paste and soldering flux used by same |
| CN109874237A (en) * | 2019-03-11 | 2019-06-11 | 深圳市海能达通信有限公司 | SMT welding procedure and steel mesh for SMT welding procedure |
| CN112040669A (en) * | 2020-09-15 | 2020-12-04 | 扬州海科电子科技有限公司 | SMT (surface mount technology) welding process for PCB (printed circuit board) in shell |
-
2021
- 2021-06-03 CN CN202110619556.9A patent/CN113395840A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05291314A (en) * | 1992-04-10 | 1993-11-05 | Fujitsu General Ltd | Soldering of bare chip |
| CN101072886A (en) * | 2003-11-06 | 2007-11-14 | 铟美国公司 | Anti-tombstoning lead free alloys for surface mount reflow soldering |
| CN101925262A (en) * | 2010-08-02 | 2010-12-22 | 深圳和而泰智能控制股份有限公司 | Steel mesh and PCB (Printed Circuit Board) |
| CN102166689A (en) * | 2011-03-30 | 2011-08-31 | 浙江强力焊锡材料有限公司 | Halogen-free lead-free soldering paste and soldering flux used by same |
| CN109874237A (en) * | 2019-03-11 | 2019-06-11 | 深圳市海能达通信有限公司 | SMT welding procedure and steel mesh for SMT welding procedure |
| CN112040669A (en) * | 2020-09-15 | 2020-12-04 | 扬州海科电子科技有限公司 | SMT (surface mount technology) welding process for PCB (printed circuit board) in shell |
Non-Patent Citations (1)
| Title |
|---|
| NING-CHENG LEE: "《Reflow Soldering Processes and Troubleshooting: SMT,BGA,CSP and Flip Chip Technologies》", 31 December 2002, 《NEWNES》 * |
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Application publication date: 20210914 |