The Alpha LR721H2 is a low residue solder paste designed for stencil or screen printing in surface mounting processes and other demanding electronic assemblies applications which post-soldering removal of flux residues is not required. The features of Alpha LR721H2 solder paste are as follows:

• Barely visible flux residues
• Long stencil life time
• High reliability
• No solder balling after reflow
• Excellent printability
• Resistant to hot slump

The working life time of the paste on metal mask or mesh screen is eight hours or longer. Its tack time is eight hours under air-conditioned environment. LR721H2 paste is available in differen combinations of metal alloy, metal %, mesh size and viscosity. Typical paste configuration are as follows:

The residue of the Alpha LR721H2 is effectively cleaned by ordinary solvent, such as Alpha 565, non-CFC Ozone friendly BIOACT EC-7R semi-aqueous cleaner.

LR721H2 paste can be reflowed by a variety of equipment such as hot plate, IR, hot air, etc. in normal or inert atmosphere. The following temperature profile is recommended as reference to reflow this paste with 63/37 or 62/36/2Ag alloy.

Total heating dwell time may be varied depending on thermal inertia and component sensitivity.

LR721H2 is available in 500 gm/jar or in cartridge and syringes upon request.