As a leader in soldering technology, Indium Corporation offers a number of solder pastes for Pb-free assembly. Indium offers many different alloy choices and flux technologies to solve many of your process challenges.

Indium Corporation’s Pb-free solder pastes are ideal for miniaturized components and fine-pitch assembly. They provide first-class printing and robust reflow performance and are all designed to AVOID THE VOID®.

Avoid the Void

Avoid shortened product life; avoid field failures; avoid customer dissatisfaction, plus a whole lot more with Indium Corporation’s advanced solder paste technology.

Indium Corporation’s suite of solder pastes offers formulations designed to deliver low-voiding, plus enhanced benefits such as improved response-to-pause, stability, HiP minimization, reliable in-circuit testing, and enhanced SIR performance.

Indium10.1HF Solder Paste minimizes solder beading and offers outstanding performance compared to the competitive material.

The solder beading test is designed to be a worst-case scenario and uses pad designs that aggravate solder beading.

Indium10.1HF is an air reflow, no-clean, halogen-free, Pb-free solder paste specifically formulated to have ultra-low voiding, especially for designs that incorporate large ground pads otherwise known as bottom termination components (BTCs). BTCs include packages such as QFNs, DPAKs, and MOSFETs. The flux chemistry is specifically engineered to improve reliability by minimizing voiding and maximizing ECM and head-in-pillow performance while also providing excellent wetting, solder beading, solder balling, and slump to meet IPC specifications. It is compatible with lead-free alloys such as SnAgCu, SnAg, and other alloy systems favored by the electronics industry.

Indium Corporation manufactures low-oxide spherical powder composed of a variety of Pb-free alloys that cover a broad range of melting temperatures. Types 3 and 4 powders are standard offerings with Pb-free alloys. The metal percent is the weight percent of the solder powder in the solder paste and is dependent upon the powder type and application. Standard product offerings are detailed in the specifications table.

Refrigerated storage will prolong the shelf life of solder paste. Solder paste packaged in cartridges should be stored tip down.

Solder paste should be allowed to reach ambient working temperature prior to use. Generally, paste should be removed from refrigeration at least 2 hours before use. Actual time to reach thermal equilibrium will vary with container size. Paste temperature should be verified before use. Jars and cartridges should be labeled with date and time of opening.

Stencil Design:

Electroformed and laser cut/electropolished stencils produce the best printing characteristics among stencil types. Stencil aperture design is a crucial step in optimizing the print process. The following are a few general recommendations:

•  Discrete components—A 10–20% reduction of stencil aperture has significantly reduced or eliminated the occurrence of mid-chip solder beads. The “home plate” design is a common method for achieving this reduction.
•  Fine-pitch components—A surface area reduction is recommended for apertures of 20mil pitch and finer. This reduction will help minimize solder balling and bridging that can lead to electrical shorts. The amount of reduction necessary is process-dependent (5–15% is common).
•  For optimum transfer efficiency and release of the solder paste from the stencil apertures, industry standard aperture and aspect ratios should be adhered to.

Cleaning

Indium10.1HF is designed for no-clean applications; however, the flux can be removed, if necessary, by using a commercially available flux residue remover.

Stencil cleaning is best performed using isopropyl alcohol (IPA) as a solvent. Most commercially available non-water-based stencil cleaners work well.