The Superconductive Circuit Board

    What You Should Know About Immersion White Tin PCB Manufacturing

    If you work with printed circuit boards or the PCBA industry, then you have probably heard of immersion white tin, but may have questions about how it actually works and whether it's a process that you should care about.

    Given that we are leaders in immersion white tin PCB fabrication here at Omni, it goes without saying that we are heavily in favor of its use. To understand why, you first have to understand the reason behind our preference for white tin in the first place. Traditionally, circuit boards have been finished with a coating of material, usually containing lead, as part of the soldering process. That's great for the functionality of printed circuit boards, but less friendly for the environment since these metals (and the byproducts created) can be extremely toxic.

    Understanding PCB Manufacturing: Silk-Screening

    One of the more artistic processes in a PCB manufacturing facility is the application of Silkscreen known in the old days as Ident layers.

    Silkscreen is usually white and human readable letters, normally used to identify components, test points, PCB and PCBA part numbers, warning symbols, company logos, date codes and manufacturer marks.

    Silk-screening requires specially formulated inks. The standard colour is white, but you can also select red, blue, black, yellow, etc.

    Understanding PCB Manufacturing: Electrical Testing

    PCB manufacturing facilities routinely perform Electrical Testing with “Flying Probe” testers which are well suited to smaller production runs.

    For short runs, the flexibility of quick set-up ensures cost effective Flying Probe tests outperform the lead-time, cost and fixed designs of dedicated test beds. With Flying Probe tests, no fixtures need to be prepared, only data files.

    Flying Probe tests are able to reveal not only shorts and opens produced by the manufacturing process but have also been known to expose design errors.

    Understanding PCB Manufacturing: Multilayer Assembly

    One of the more interesting activities routinely associated with PCB manufacturing is the process of assembling multilayer circuit boards.

    At any given time 40% of our PCB manufacturing at Omni is producing multilayer circuit boards, so understanding the process is important. Layers of copper foil, prepreg and core material are sandwiched together under high temperature and pressure to produce multilayer assemblies. Pressure is needed to squeeze out air while heat is required to melt and cure the thermosetting “prepreg” adhesive which holds the multilayer PCB together.

    Understanding PCB Manufacturing: CNC Drilling

    One of the key processes in a PCB manufacturing facility is the CNC Drilling Department.

    Holes are drilled in PCBs for two main reasons:

    Customer requirements.- component mounting and to promote conductivity between Cu layers (vias)

    Manufacturing requirements.- to ensure precise registration and to help the operator ensure each drill has successfully completed the tool path. 

    PCB Finishes - White Tin, Immersion Tin, Immersion White Tin and Whiskers

    Mention Immersion White Tin around sales people from PCB shops and Tin Whiskers will inevitably be part of the topic.

    They may not feel comfortable down mouthing the competition in public but a process? Well that’s fair game. What the salespeople don’t know or won’t tell you is the Immersion Tin used as a finish for circuit boards completely dissolves in the solder used in the circuit board assembly process.