| hello...can somebody help me regarding the POPCORN at Reflow. What is this POPCORN at reflow, what it looks like, its cause and corrective action if there is... | | your help is greatly appreciated...thanks | | omat marasigan | | Omat baby,
Moisture sensitivity is becoming a popcorning issue with more of us. It is so much so with us now, we may prematurely release a process without our usual exhaustive evaluation and qualification.
Mostly, this phenomonon involves moisture sensitive parts. These parts encompass many varieties and styles, though mostly BGA types. Most all popular BGA's, and many other leaded/plastic parts (in particular) are moisture sensitive requiring special attention before soldering operations.
Included in popcorning prevention is a specified process involving buying parts presealed and certified safe from various suppliers. Inside moisture sensitive/ESD protective bags are certs, dessicants, and moisture sensitive labels. Assurance must be provided, first, from the supplier their moisture sensitive parts are moisture protected.
Next, upon opening your prize parts, you must continue moisture sensitive assurances. This is done using IPC/supplier specifications concerning how long parts may be left exposed to the environment, under what conditions, before they must be rebaked/resealed and reused.
IPC has pretty good guidelines supporting most supplier moisture sensitive requirements. They range from 1 through 6 classes of sensitivity. This means some parts are less/more sensitive than others and require more/less attention to use/time factors.
Anyway, if your parts are moisture sensitive and you do not pay attention to moisture sensitive requirements, and you solder them in reflow or over the wave, you will blow the little bastards apart. Any more questions?
I wish you the best while hoping you don't end up eating some of the results,
Earl Moon
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