Mil/aero PCB applications continue to be largely leaded-based with virtually no movement toward RoHS. The main reason is those leaded PCB designs have passed stringent certifications and proven to be successful. So mil/aero equipment manufacturers are highly reluctant to do any re-designs. Like the old axiom states, ‘If it’s not broken, don’t fix it.’
Therefore, the burden falls on the EMS Provider and contract manufacturer (CM) to place special emphasis on the design, fab, and assembly of leaded-based PCB designs. However at times, a few projects call for hybrid leaded and RoHS lead-free assemblies. And that’s when extra special attention kicks in to assure each and every design, fab, and assembly step is precisely followed to ensure board reliability.
EMS Providers and CMs definitely need to know about leaded vs. RoHS and the possible pitfalls involved. But it’s also a good idea to be savvy about and either being certified or in the midst of AS9100 certification, as well as having bulletproof procedures for avoiding counterfeit components.
AS9100 is defined as the international management system standard for aircraft, space, and defense industries. It demands tightly and reliability controlled and repeatable processes. It’s targeted at having aerospace industry manufacturers produce world-class quality products at a reasonable cost. One example of the highly specific requirements of AS9100 is assuring that a certain specific amount of solder paste is dispensed on a specific SM pad, and a paste height inspection machine ensures that is done, Fig. 1.
Look for our article on these highly important mil/aero issues in the May online SMT Magazine issue. It’s important for mil/aero equipment OEMs and their sub-contractors to check on the following key points to assure they are getting the utmost reliability for their projects.
- Traceability of the BOM and each component covering lot code, date, year and manufacturing codes must be strictly applied by well-trained assembly personnel.
- A CM must demonstrate the highest levels of quality by clearly proving it has instituted and formalized critical verification steps at key design and manufacturing stages.
- Get assurances the CM has a lot of embedded QA and QC steps in manufacturing providing a self-correcting mechanism.
- Understand that when a component is damaged during manufacturing, the CM must remove it, label it, return it to you, and then get a new one from the OEM.
- Don’t be fooled into thinking a CM is authorized to consign any part of your AS9100 project to outside sub-contractors.
- Find out if the CM has internal control checkpoint loops assuring inaccuracies are immediately flagged.
- Ensure the CM is abiding by ESD Control Class 0 to ensure your assemblies are 100 % compliant to the highest degree.
Lastly, CMs must take extra care in avoiding counterfeit components. Critical procedures and processes should be in place to detect the counterfeit components, if and when they creep into the system. Establishing sound relationships with reputable distributors and value-added resellers is also extremely necessary to make sure that all the components that are procured there are original and not counterfeit.