BGA rework process
The increased use of BGAs and the underlying trend of ever-smaller package sizes, finer pitches and their placement on to ever denser printed circuit boards has led to greater and greater challenges in BGA rework.
In addition to the equipment requirements for modern day BGA rework, the skill level, dexterity and process knowledge of the rework technicians working on BGA rework is even more demanding today. The BGA rework technician needs to understand reflow profiles in order to deal with printed circuit boards with a high density of ground planes.
The BGA rework technician must also understand flux chemistries and how this impacts the kind of cleaning which can be done underneath the device. The BGA rework technician must also be able to understand how a variety of conformal coatings can be removed from the PCBA as well as underneath the BGA. BGA rework technicians must also understand how device which neighbor the BGA to be reworked can or could be impacted by the BGA rework process profile.
Placement accuracies for today’s BGA rework need to be in the less than a 1mil tolerance range. In addition with the lead free packages the rework system now require sophisticated temperature control with programmable multi zone bottom heaters, nitrogen capability and low flow rates at the air nozzle.
In addition to the rework equipment set the inspection equipment needs to be of a higher capability. X-ray inspection equipment with very small spot sizes is a requirement for BGA inspection post BGA rework. The ability to measure the sphericity of the solder balls, the solder ball diameter, the ability to shoot through RF shields as well as higher density ground planes is now a necessity for the x-ray equipment requirements for BGA rework. Also the endoscope is a necessity for checking the ball collapse, the surface of the BGA ball post reflow, the wetting action as well as other attributes is important in BGA rework.