Indium Corp Frame 80Au 20Sn Thickness:0.05mm (0.00197")

Preforms come in standard shapes such as squares,rectangles, washers, and discs. Typical sizes range from.010" (.254mm) up to 2" (50.8mm). Smaller and larger sizes,as well as custom shapes, are also available. Dimensionscan be held to tight tolerances to assure volume accuracy.Selecting AlloysA wide assortment of alloys is available in liquidustemperatures that range from 47–1,063°C. Alloys can beindium-contained, gold-contained, lead-free, fusible, orstandard tin-lead, as well as many others.1. Alloy selection should be based on strength andother required physical properties, as well as thepreferred soldering temperature and the operatingtemperature of the device being soldered. A generalrule is to select an alloy that melts at least 50°Chigher than the operational temperature of the partbeing soldered.2. Next, consider the materials being soldered and whichsolder is most compatible with them. For example,tin-based solders will scavenge the gold fromgold-plated parts, forming brittle intermetallics, soindium-based solders are generally recommended inthese cases.3. Metals and alloys have different characteristics thatcan affect the ease with which they can be made intodifferent shapes and thicknesses. It is important toconsider the shape of the final preform in the alloyselection process.4. The operating environment of the completedassembly is also an important consideration foralloy selection. Will it operate in very high or verylow temperatures, or be subjected to vibration? If so,an alloy should be selected that will stand up to theseconditions.5. Our Application Engineers will work with you todetermine the best alloy for your application.Selecting DimensionsThe location of the solder joint and the volume of solderneeded will determine the size and shape of the preform.Once the flat dimensions (diameter, length, and width) havebeen determined, the thickness can be adjusted to achievethe desired volume of solder. Generally, for through-holeconnections, add 10–20% to the calculated volume for a goodfillet. For pad-to-pad joints, figure about 5% less surface areathan the pad.Each solder preform should have a burr tolerance specified.Stay as close to standard tolerances as possible to avoidadding cost and lead time to your preforms.Indium Corporation has an extensive library of sizes and shapesfrom which to choose, or we can create a setup specifically foryour application. Using an existing preform size can eliminatethe additional time associated with creating a new setup.