In SMT process, which will affect the welding quality of reflow furnace?
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In SMT process, which will affect the welding quality of reflow soldering furnace, Touch screen and OLED Forum
Reflow soldering is used to solder SMT components and circuit boards together by solder paste in SMT process.
reflow soldering is used to weld SMT components and circuit boards together by melting solder paste coated on circuit board pad.
SMT materials include SMT components, circuit boards and solder paste.

In SMT process, which will affect the welding quality of reflow furnace?

the quality of SMT materials is very important for reflow soldering quality The influence of SMT materials on the quality of reflow soldering.
8 d # U. \% D5 L: H) l / D6 P* x: t2 _' Influence of G & Y: y% H1 H - SMT components on reflow soldering quality5 Z + L # C) e / K when SMT components or pins are oxidized or polluted.
SMT reflow soldering will produce poor wetting, virtual soldering, voids and other welding defects.
coplanarity of components is not good.
it will also lead to virtual soldering and other welding defects.
SMT reflow soldering will produce poor wetting, virtual soldering, voids and other welding defects! Z8 b2 w' P    L& ~* P# F2 W% X. x) l / C. X4 S2 O8 V 2. Effect of SMT circuit board on reflow soldering quality o1 o6 G! V.
uThe assembly quality of SMT has a direct and very important relationship with the pad design of SMT circuit board.
if the pad design of printed circuit board is correct.
a small amount of skew can be corrected due to the surface tension of molten solder during reflow soldering; On the contrary, if the PCB pad design is not correct, even if the mounting position is very accurate, after reflow soldering, there will be welding defects such as component position offset, stele and so on: SMT assembly quality also has a certain relationship with PCB pad quality,The solder pad of printed circuit board is oxidized or polluted, and the solder pad of SMT chip printed circuit board is moistened, which will lead to poor wetting, false soldering, solder ball, void and other welding defects during reflow soldering.
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A0 m5 J3 u7 v2 z3、 Influence of solder paste printing on reflow soldering quality0 h% ^: j + ~ 4 N #, f / h4h - H solder paste has certain requirements on the content of metal powder, oxygen content, viscosity, thixotropy and printability of metal powder.
if the content of metal powder in solder paste is high.
when refluxing and heating up, the metal powder will fly with the evaporation of solvent. If the oxygen content of metal powder is high, it will aggravate the flying and form solder ball, In addition,
if the viscosity of solder paste is too low or the thixotropy of solder paste is not good, the solder scale pattern will collapse after printing, even cause adhesion, and solder ball bridging and other welding defects will be formed during reflow soldering.
if the printability of SMT solder paste is not good.
the solder paste only slides on the template during printing, In this case, the solder paste can not be printed at all.
improper use of solder paste.
if the solder paste is taken out from the refrigerator and used directly, water vapor will condense. When refluxing and heating up, water vapor will evaporate and bring out metal powder. At high temperature, water vapor will oxidize the metal powder, spatter and form solder ball, and cause poor wetting/ |7 c5 D8 H" g3 M$ o' b( N8 K- e9 R8 N9 B. A.
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