This column contains key topics that I included in my PCBA Manufacturing Requirements document. Commonly used industry standards are referenced and used wherever possible.

After working with our EMS partners for several years, I have discovered that it is not good to take things for granted; language and cultural differences can cause misunderstanding. Manufacturing expectations should be documented clearly and discussed with your EMS partners to ensure that there are no misinterpretations of what is expected.

Requirements

ESD Handling: Electrostatic sensitive devices shall be handled in accordance with ANSI/ESD-S20.20, “Protection of Electrical and Electronic Parts, Assemblies and Equipment.”

MSDs: Moisture sensitive device handling is governed by J-STD-033, ”Handling, Packing, Shipping and Use of Moisture/Reflow Sensitive Surface Mount Devices.”

Component Packaging: Partial reels, trays, and tubes are acceptable when the original packaging (tape, reel, trays, and tubes) is being used. Split — i.e. one reel has been split into two reels — reels, trays, and tubes are not acceptable. Tape and reel materials shall meet the requirements of the EIA-481 standards.

Component Solderability: All components shall meet requirements of J-STD-002, “Solderability Tests for Component Leads, Terminations, Lugs, Terminals and Wires.” Components more than five years old must be recoated. Those 2?5 years old shall be checked per J-STD-002, recoated if necessary. Components 0?2 years old are considered acceptable unless otherwise noted.

PCBs: All PCBs shall meet the solderability requirements of J-STD-003, “Solderability Tests for Printed Boards.” Shelf life limitations for HASL and ENIG are date code plus 12 months; shelf life for OSP and ImmAg are date code plus 9 months. Baking is required if the shelf life is exceeded. OSP and ImmAg PCBs must be re-coated after baking. Only one bake cycle should be performed. If the PCBs are not used within the noted shelf life after baking and recoating they are to be scrapped.

Flux: All fluxes shall be tested and classified by the manufacturer with J-STD-004, “Requirements for Soldering Fluxes.” Water-soluble fluxes shall be cleaned to manufacturer’s recommendations. No-clean flux shall be cleaned when the residue has not been exposed to peak soldering temperatures. The primary concern is wave and hand soldering flux that did not contact molten solder.

Solder: All solder pastes shall be tested and characterized by the manufacturer according to J-STD-005, “Requirements for Solder Pastes.” All solder alloys shall meet the requirements of J-STD-006, “Requirements for Electronic Grade Solder Alloys and Fluxed and Non-fluxed Solid Solders for Electronic Soldering Applications.”

Workmanship Standards: PCBs must be inspected and accepted or rejected using IPC-A-600, “Acceptability of Printed Boards.” PCB assemblies (PCBAs) shall be inspected and accepted or rejected using IPC-A-610, “Acceptability of Electronic Assemblies.” IPC-7095, “Design and Assembly Process Implementation for BGAs,” shall be used as a reference for BGA solder joint voids.

Rework and Repair Standards: PCBs and PCBAs are to be reworked and repaired in accordance with IPC-7711 and IPC-7721, “Rework, Repair and Modification of Electronic Assemblies.”

Stencils: Stencils for solder paste printing shall be designed and fabricated in accordance with IPC-7525, “Stencil Design Guidelines.”

First Article Inspection Record: A first article inspection (FAI) record is required for each PCBA. The FAI record should be completed during the first prototype build in accordance with the PCBA First Article Inspection procedure. The finished FAI record shall be submitted to the on-site quality engineer.

Quality Metrics: Key quality metrics should be measured, documented, and reviewed on a weekly basis in accordance with the External Quality Metrics Guideline procedure. IPC-7912, “End Item DPMO for Printed Circuit Board Assemblies,” shall be used for defects per million opportunities (DPMO) calculation. The finished metrics package then should be submitted to the on-site quality engineer.

Root Cause and Corrective Action: Structured problem solving and failure analysis techniques are used to identify the root cause of PCBA quality problems. Short- and long-term corrective actions must be implemented to contain and fix problems. Problem solving, failure analysis, and corrective action reports are to be provided when requested by quality engineers.

Reliability Testing: Solder joint reliability testing is not required unless requested and specified in writing. Reliability testing shall be based on IPC-SM-785, “Guidelines for Accelerated Reliability Testing of Surface Mount Solder Attachments,” and IPC-9701, “Performance Test Methods and Qualification Requirements for Surface Mount Solder Attachments.”

Conclusion

I rely heavily on industry standards, mostly from IPC. After creating and releasing this document for your own company, review it with your EMS partners so they understand what is expected. I recommend auditing each EMS site at least once every 12 months to ensure your requirements are being followed.

Robert Rowland is an SMT Editorial Advisory Board member, instructor, and co-author of Applied Surface Mount Assembly. He is process engineering manager at RadiSys Corp., Hillsboro, Ore.; technical conference director of SMTAI; and recipient of the SMTA Founder’s Award. Contact him at (503) 615-1354; rob.rowland@radisys.com.