SMT chip manufacturer introduces lead free reflow soldering temperature adjustment method
Author:Li Li Time:2021-06-07 13:34 Browse(78)
SMT chip manufacturers introduce lead-free reflow soldering temperature debugging method, touch screen and OLED forum
3 f1 j9 T* t- \- H+ }9 g1 j: ]2 p+ h* G3 U' B8 Q; ^ 4 y8 v( o/ B1 F3 N" nFor lead-free solder paste, the temperature difference between components must be as small as possible.
this can also be achieved by adjusting the reflow temperature.
using the traditional temperature curve.

SMT chip manufacturer introduces lead free reflow soldering temperature adjustment method

although the temperature difference between components is inevitable when the plate forms the peak temperature, it can be reduced by several methods:0 N0 q4 @7 z    y+ |) r, e! \ 8 u+ X! k2 _" b    Q4 h # T - C I. lengthen the preheating time.
this greatly reduces the temperature difference between the components before the peak reflow temperature is formed.
most convection reflow furnaces use this method.
however.
because the flux may evaporate too fast through this method, it may cause poor wetting, due to the oxidation of the pin and pad.
this method can be used in many convection reflow furnaces+ B4 {5 t( c1 Q2 Q6 n6 k: \; v.
?) The traditional preheating temperature is generally 140 ~ 160 ℃ ° C.
it may be necessary to increase the lead-free solder to 170 ~ 190 ° C.
increasing the preheating temperature reduces the required peak temperature.
this in turn reduces the temperature difference between the components (pads).
however.
if the flux can not accept higher temperature levels, it will evaporate, resulting in poor moisture, because the pad pins are oxidized.
; h( v" `8 y3 V' V$ k! {' [% P9 B! p7 R3、 Trapezoidal temperature curve (extended peak temperature).
the results show that the temperature curve is linearProlonging the peak temperature time of small heat capacity components will allow the components and large heat capacity components to reach the required reflux temperature and avoid overheating of small components.
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