Analysis of causes of incomplete melting solder paste in reflow soldering by reflow soldering manufacturer
Author:Shi Mingyue Time:2021-06-07 17:57 Browse(884)
Reflow soldering manufacturers analyze the causes of incomplete melting solder paste, touch screen and OLED forum
Reflow soldering equipment is used in reflow soldering technology. There is a heating circuit inside the equipment, which heats the air or nitrogen to a high enough temperature and then blows it to the circuit board that has been attached to the component, so that the solder on both sides of the component will melt and bond with the motherboard.
the advantage of this process is that the temperature is easy to control.
oxidation can be avoided during soldering, The manufacturing cost is also easier to control.

Analysis of causes of incomplete melting solder paste in reflow soldering by reflow soldering manufacturer

however, due to some reasons, the solder paste reflow soldering may not completely melt.
Zhichi technology reflow soldering is here to share with you the reasons.
this paper introduces the current situation of Zhichi technology reflow soldering8 Y- r: x9 d) R' [) K) m9 \$ E; d$ f- T/ E.
_ 4 r. P6 G( H* w9 I' f3 E0 _( i" i7 J0 A$ Y1. When all or most of the solder joints of the surface assembly board have incomplete melting of solder paste, it means that the peak temperature of reflow soldering is low or the reflow time is short, resulting in insufficient melting of solder paste* X7 O7 F/ i% T% s$ l) P4 s4 Y# X1 A* B1 [! q9 ? 2. When large size PCB is welded, the solder paste is not completely melted on both sides of the transverse direction, which indicates that the transverse temperature of reflow soldering furnace is uneven.
this situation generally occurs when the furnace body is narrow.
the insulation is poor.
because the temperature on both sides of the transverse direction is lower than that in the middle;" a7 u6 z+ o+ g0 MWhen the incomplete melting of solder paste occurs in the fixed position of the surface assembly board.
for example, when large solder joints, large components, and the surrounding of large components, or when it occurs in the back of the printed circuit board where the large heat capacity devices are attached, the components absorb too much heat or the heat conduction of reflow soldering is blocked0 Z5 v0 {/ W7 g- `: C7 {- Y7 S1 f (z1 V3 R% H4) and reflow soldering equipment itself.
during infrared furnace welding, because dark color absorbs more heat, black devices are about 30 ~ 40 ℃ higher than white solder joints, so the temperature of devices on the same PCB is different due to different colors and sizes.
the temperature of devices on the same PCB is different* Z% ?; V5 i" o   }  ^. E; @) w.
n7 r1 f4 K% y+ W! F5. Solder paste quality problems, high oxygen content of metal powder, poor performance of flux, or improper use of solder paste: if the solder paste is taken out from the low-temperature cabinet and used directly, because the temperature of the solder paste is lower than the room temperature, water vapor condensation occurs, that is, the solder paste absorbs the water in the air, mixes the water vapor in the solder paste after stirring, or uses the recovered and expired solder paste.
9 w% J - [& H% J $Q + I1]: A6_ 9 a+ o2 @* v    i- V. T6 Y$ V+ b   ] 3 D' k+ u5 j: r8 ^! N; e0 V8 `; x% X( c5 t* C+ R/ E5 A) f.
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