Quality Comparison Ranking of Soldering Processes

This topic is a purely hypothetical. The facts listed here are based on working in a perfect production environment, with pre-products that have no variations etc. it does not represent reality. Process variables in packaging and interconnection technology and the final soldering quality all depends on optimum layout geometries of the assemblies, pin-pad component geometries and wetting-friendly metallization of all components involved. Furthermore, the associated fluxes and soldering materials as well as the integrated soldering automation concept must be taken into account.

Nevertheless, which soldering process delivers the best results is a question we like to examine from the purely technical side. The following soldering process comparisons are based on a physical quality. The process capability index Cpk or the parts per million (ppm) values are initially evaluated independently and thus do not depend on the soldering automation manufacturer.

Whereby the actual ppm tolerance range very much dependents on the core competence and professionalism of the soldering automation manufacturer.

The quality key figures of Cpk, ppm and percentage waste are based on the following conversions:

1ppm=0.0001% 0.3 as Cpk value equals 32% equals 320,000 ppm

1.00 as Cpk value equals 2.7% equals 2700 ppm

1.33 as Cpk value equals 0.0063% equals 63 ppm

Ranking of the quality-comparative soldering processes:

Mini wave soldering process under inert gas: 0.01 to 0.05 %: 100 to 500 ppm

Laser soldering process: 0.1 to 3% = 1,000 to 30,000 ppm

Piston soldering process: 0.9 to 7% = 9,000 to 70,000 ppm

Thermode soldering process: 0.3 to 3% = 3,000 to 30,000 ppm

Induction brazing process: 0.3 to 3% = 3,000 to 30,000 ppm

For comparison:

Reflow soldering process: 0.005 to 0.030%: 50 to 300 ppm

With this approach, all selective soldering processes can be evaluated in relation to each other and put into an overall economic understanding including additional framework conditions. For a predictive quality assessment, process evaluation under real process conditions is therefore indispensable. This approach allows the possibility of the planned investment decision.