1.First of all, the Specific adhesive should be one type and not mix up. Mix adhesive is not acceptable.
2.Dispens length: 25% to 35% of the package length.
3.Dispense width: In order to obtain the required dispense height below.
4.Dispense height: Minimum 25% of the BGA substrate. Not including the solder ball.
Maximum height: Not to exceed the top surface of the BGA package, exclude the heat-spreader.
5.No void or gap is permitted within the dispensed bead.
Post cure inspection:
1.Post cure inspection is required at 100 percent of every edge bonding.
2.Use pick instrument to test the material. Check for any uncured by pushing the tip of the pick against the material.It should not be deformed or soft/gel-like.
3.Provide failure analysis report for all edge bonding defects.
Edge bonding removal and rework:
1.Hot air rework system is set to 180 degrees heat for 3.5 seconds before attempt to remove the edge bonding material.
2.Use tweezers to peel off the edge bonding materials.
3.Re-edge follow acceptance criterion as above.
Below is the recommended cure parameters(Only apply to UV glue):
1.Cure tiem minimum 10 seconds.
2.UV wave-length 320~360nm
3.UV light source metal halide
4.Lamp intensity 250mw per cm2
5.UV measuring radiometer frequency: 1 per 2 days.