PCB Assembly

A good electronics manufacturer tailors the reliability of his processes and assemblies to suit his customer base. AirBorn Electronics designs and manufactures Printed Circuit board assemblies to a standard compatible with professional quality equipment. Many of our customers sell expensive niche market equipment. They really do not want to have a breakdown caused by a manufacturers decision to use an economical 10c IC socket in place of a more reliable 50c part. We have other clients who sell into higher volume commodity-product markets, and different design rules apply to their work due to the economies of scale.

Our assemblies are designed to be maintainable, repairable, durable and easily installed. The difference between a printed circuit board that is easy to work with and a PCB which bedevils technicians can be as simple as proper labelling, connectors and sockets. At AirBorn Electronics we have developed some maxims which we try to work by -

AirBorn Electronics manufactures products to a professional equipment standard:
1. IC Sockets are gold plated (DIP type are Gas tight machine screw construction with 4 prong gold plated mating surfaces)
2. Data connectors have Gold plated mating surfaces
3. PCB Laminates are professionally manufactured using Fibreglass FR4 stock, soldermask over bare copper (top & bottom), PTH, solderable finish, and silkscreen encoded with a full component identification legend.
4. All connectors are polarised, with numbering clearly marked.
5. All interboard cabling is stranded. All light wire is tinned stranded.
6. Components subject to lowered MTBF due to external adverse factors (e.g. line drivers) are socketed.
7. All socketed components are identified, with orientation shown.
8. All parts used are first grade, new, manufacturers product meeting the full manufacturers specification.
9. All non-substitutable-at-repair components are clearly marked.
10. All parts & PCBs have been processed under anti-static conditions.

Quality is not goodness. -- Sandia National Labs document

Standards (a bit of a rant) Its all very well to have an ISO9000 Manufacturer produce your boards, but if the design is not up to scratch the end result may well be faithfully reproduced ISO9000 compliant junk. Standards rarely specify quality of design - indeed, when they try to do this they usually create such a rigid inflexible environment that nothing useful gets produced. Even with our "top ten" criteria above, there will be projects where the best design choice involves breaking one of the rules. It is fantastic to have a strong standards base for your products and designs, but by and of itself it is not the whole answer. Your most important resource in technical manufacturing are your People and your systems, and standards really seem to fit in to that mix as "codified systems."

By extending the engineering design into the specification of the manufacturing operation, AirBorn Electronics can increase the quality of the final product. By being available to respond to the changing engineering requirements that arise from time to time in manufacturing, we can help ensure the highest quality final product in the longer term.

Communicating manufacturing information is a critical issue. We now generate all manufacturing documents (Gerbers and BOM in particular) in house rather than forwarding CAD files. We have a standard method for transferring "miscellaneous notes" to third party manufacturers, we put the notes in the

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BOM either alongside the parts affected or as a note applying to the whole printed circuit board. The (realistic) rationale is that all subcontract assemblers have to reference the parts list to produce the board.

Previously (as soon as 5 years past) we relied on either marking up the board overlay (as pictured) or communicating the requirements directly to the manufacturer. However, as we have been told, english may not be the first language of many assembly staff. And communicating requirements ourselves is not always practical when the client deals directly with the manufacturer; so our system has adapted.

Most electronics manufacturers have converted their stocks of parts to Sn (Tin) finish parts that are Lead free and ROHS compliant. However, it is still the customers option to choose ROHS compliant production or to allow tin/lead solder and board finishes. The tin/lead solder and board finishes are required for most defence projects and are allowed for legacy production. There is a slight cost reduction in producing tin/lead finish PCB laminates. ROHS compliance must start at the design stage of your project with selection of ROHS compliant parts. This is not difficult and so we produce every design as ROHS compliant without being asked. If the client wants ROHS compliant production, they need to request it, but the design is ROHS compliant by default.

AirBorn Electronics' custom design does not carry with it an obligation to have us involved with the product manufacturing - the customer owns the design. The fact that many of our customers do choose to have us involved with the manufacture (and not just the design) of their PCBs perhaps illustrates that we have the quality/price tradeoff set at the right point for our market. Experience counts for a lot.

In theory, there is no difference between theory and practice. But in practice, there is. -- Yogi Berra (attributed to)

HW Doc Overview Custom Economies of scale