Description

<style>.e_editor{font:14px/24px Roboto,Helvetica,Tahoma,Arial,'Microsoft YaHei','b8bf53';}.e_editor div,e_editor p,e_editor td,e_editor th,e_editor li{font-weight:inherit;font-size:inherit;font-style:inherit;font-family:inherit;}.e_editor ul{margin:-10px 0 20px;}.e_editor li{padding:5px 0;}.e_table{width:96%;border-collapse:collapse;empty-cells:show;}.e_table th,.e_table td{padding:5px;border:2px solid #eee;}.e_img{padding:10px 0;text-align:center;}.e_p{line-height:20px;padding:0 0 20px;text-indent:0em;}</style> <div class="e_editor"> <div class="e_p"> we have a issue of post-reflow oven (SMT) soldering defects of blowholes and pinholes. Any suggestions or knowledge on root cause is appreciated to be share? </div> <div class="e_p"> BACKGROUND : </div> <div class="e_p"> we DI water wash and oven bake the PCB bareboards at 90deg-C for 60mins, to remove possible dust, volatiles and also thermal condition the PCB (polymide). </div> <div class="e_p"> The reflow oven profile plotting shows the profile to be within specs for the "supplier recommended specs". </div> <div class="e_p"> Preheat between 150-180degC is average 60-75sec. </div> <div class="e_p"> Reflow above 183degC is average 45sec. </div> <div class="e_p"> Ramp is 1.7degC/sec. </div> <div class="e_p"> Peak reflow temp averages 208degC max. </div> <div class="e_p"> The component solder fillet affected is a MLF. </div> <div class="e_p"> we control the environment to be 22-26degC at 40-60RH%. </div> <div class="e_p"> post-reflow inspection shows blowholes at solder areas near to the base of the PCB pad. Although it also manifests as a violent explosion appearance the the top of the solder fillet region. </div> <div class="e_p"> post-reflow inspection also shows pinhole in solder areas random in the solder fillets. </div> <div class="e_p"> we tried to increase reflow time, it appears to reduce the occurence of blowhole, and marginal helps in the pinhole reduction. Any ideas how to further eliminate the pinholes? </div> <div class="e_p"> we did try increasing the reflow peak temperature to average 215-218degC, but that just increased the rate of blowholes. </div> <div class="e_p"> Appreciate any ideas or suggestions, on how to eliminate this blowhole and pinhole issue. Thanks in advance! </div> </div>