Solder Preform Technique

The solder EZREball™ preform technique used for reballing area array devices is one of the methods used at BEST for the attachment of solder balls. This patented process was developed primarily with the speed of attachment and simplicity in mind. The key to this method is the engineered polyamide and other polymer-based carrier ("preform") which holds the solder balls in place. After applying flux to the bottom of the part, the balls and part land patterns are aligned and “squared up”  the device by aligning the land patterns of the device on top of the perform ball locations. The assembly is then reflowed. After being cooled the perform is simply peeled away. (User Instructions) Finally the part is cleaned and inspected.

The major advantage of this technique is in its convenience as the solder balls are packaged inside a preform. Each unique solder alloy, ball size and grid pattern requires a new preform.

Materials Required

• EZReball™ solder preform
• Tacky flux
• “Square up” fixtures for preform
• Tweezers
• Cleaning brush
• Isopropyl alcohol
• Reflow oven
• Stereo microscope
• Soft brush

EZReball™ Solder Ball Preform Reballing Process Flow

Prepare Device - see section on device preparation

Insert Preform - The EZReball™ solder preform gets loaded first into the fixture. The device and perform are aligned by “squaring up” the device to the perform. The device to be reballed is placed face down and the perform balls are aligned over the top of the package.

Spread Flux on Part- see flux spreading discussion

Insert and Seat Package onto Fixture - The part can now be loaded into the fixture. Place the area array package into the fixture with the fluxed side of the package against the preform. Seat the package properly into the fixture making sure that the package sits flat against the preform.

Reflow Part - see reflow discussion above

Peel Back Carrier and Clean Off
After being cooled the EZReball™ preform can be pulled off of the package.
Using Isopropyl alcohol and soft brush the flux and adhesive residue can be clean off the package and  reflowed solder balls.

Rinse Package
The package can be either air dried using a static neutralizing gun or with nitrogen.

Cleaning - See cleaning discussion
Baking - See baking discussion
Inspection - See inspection discussion

General BGA/CSP Reballing Process
Handling of BGAs
StencilQuik™ Fixturing Technique
EZReball (TM) Preform Technique
Dry Packaging
Ceramic Package Reballing
Reballing Challenges
Optional Services