IPC J-STD-004B Requirements for Soldering Fluxes

The IPC J-STD-004B standard published by the Printed Circuits Institute (IPC) describes general requirements for the classification and characterization of fluxes for high quality solder interconnects. This standard is generally used for quality control and purchasing purposes.

The purpose of this standard is to classify and characterize tin/lead and lead-free solder paste materials for use in electronic metallurgical interconnects for printed circuit board assembly. Soldering flux materials include: liquid flux, paste flux, solder paste, solder cream, as well as flux-coated and flux-cored solder wires and preforms.

It is not the intent of this standard to exclude any acceptable solder or solder material. However, these materials have to produce the desired electrical and metallurgical interconnection.

Flux requirements are defined in general terms for standard classification. Additional information to help users understand some of the requirements of this standard is included in the annex to the standard (Appendix B). In practice, where stricter requirements are required or other production processes are used, the user must define them as additional requirements.

For order purposes and assignment according to other specifications, the flux definition system presented in the standard is mainly used (Table 1-1).

For the purposes of this standard, flux refers to a chemically and physically active formula that promotes wetting of the metal surface by the molten solder by removing oxides or other surface films from the base metals and solder. Flux also protects surfaces from re-oxidation during brazing and changes the surface tension of the molten solder and base metal.

In general, fluxes are used for the following purposes:

• Aiding the wetting process by removing oxidized layers from metallic surfaces and changing their surface tension.
• To protect the surfaces of both the solder and the parts to be soldered from oxidation during the soldering process.
• To aid heat transfer between soldered parts and thus try to equalize their temperature.

Among the numerous tests, measurements, analyses, and evaluations our organization provides for businesses in various sectors, we also offer testing services for soldering flux requirements under the IPC J-STD-004B standard, utilizing a trained and expert staff and advanced technological equipment.