Although this yields effective cleaning results, process productivity may be compromised. Given the maximum allowable wash temperature, difficult cleaning applications are met by increasing the wash exposure time including reducing the conveyor speed of inline cleaners or extending wash time in batch cleaners. Building equipment out of stainless steel is an option, but one that may be cost prohibitive. In most cases, this is due to thermal limitations of the materials used to build the polymer-based cleaning equipment. Over time, cleaning agent formulations have advanced to match new solder paste developments, spray system configurations have improved, and wash temperatures (thermal energy) have been limited to a maximum of 160✯.
The pump system, which includes spray pressure, spray bar configuration and nozzle selection, is optimized for the specific process to create an efficient cleaning system.Īs board density has increased and component standoff heights have decreased, cleaning processes are steadily challenged. The chemical energy is derived from the engineered cleaning agent the thermal energy from the increased temperature of the cleaning agent, and the mechanical energy from the pump system employed within the cleaning equipment. Regardless of the type of cleaning process adopted, effective cleaning of post solder residue requires chemical, thermal and mechanical energies. For defluxing applications, the most common systems are spray-in-air, employing either batch or inline cleaning equipment and an engineered aqueous based cleaning agent. If a decision to clean substrates is made, there are numerous cleaning process options available. These failures have been well documented. If ionic residues remain on the substrate surface, potential failure mechanisms, including dendritic growth by electrochemical migration reaction and leakage current, may result. OEMs and CMs designing and building electronic assemblies for high reliability applications are typically faced with a decision to clean or not to clean the assembly. Higher Defluxing Temperature and Low Standoff Component Cleaning - A Connection?
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