This paper analyzes the bridging problem of circuit board components after reflow soldering in SMT chip production
Author:Peng Lei Time:2021-06-07 17:57 Browse(704)
Analysis of SMT chip production process after reflow soldering circuit board components bridging problem, touch screen and OLED forum
8 _! f/ U9 `+ U    W! ?* L" y7 N0 M* U) l# C: U4 x( J8 m; E&F3 R # D + H1 ^% A1, solder paste quality problems cause SMT reflow soldering components to bridge for 7 s    l1 L- B: a1 x( \       The metal content in solder paste is high, especially after printing for a long time; The solder paste has low viscosity and diffuses out of the pad after preheating; The solder paste has poor slump and flows out of the pad after preheating; All of these will cause IC pin bridging.
all of these will cause IC pin bridging1 I' q- d. P- o9 A- E7 I0 u. ~: l.
K9 Z9 p1 Q. ~: m& q2. SMT solder paste printing problems caused by SMT reflow soldering component bridging) R7 Y! o' J6 C$ [. X: v: p       The solder paste printing machine has poor repetition accuracy, uneven alignment, and solder paste printing is outside the solder pad, which can be seen in the production of QFP with fine spacing.

This paper analyzes the bridging problem of circuit board components after reflow soldering in SMT chip production

poor alignment of steel mesh, poor alignment of PCB, improper size / thickness design of steel mesh window and uneven alloy coating of PCB pad.
the amount of solder paste is too much, The solution is to adjust the solder paste printer and improve the coating layer of PCB pad.
3 W3?! t3 m/ d4 Z4 G" A1 C/ h2 o' N9 X. Q$ x6 v; Q "U3, SMT reflow component bridging caused by placement problem 1 ` 2 n3o0 F% U-V% s # J       The pressure of the placement machine is too highThe collapse of solder paste after being pressed is a common reason in production, so the z-axis height should be adjusted.
if the placement accuracy is not enough.
if the components shift and the IC pins deform, the causes should be improved.
)] 8 ^ 5 / A1 ~. P)} 7 {2 n}) G* u. V! P1 H: \4. Component bridging 1 t0 [* O + Q "] after reflow soldering due to insufficient preheating of reflow welder       The temperature of reflow soldering furnace is too fast.
the solvent in solder paste is too late to volatilize, resulting in component bridging. For this reason, the temperature curve of reflow soldering should be adjusted.
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