Apple Systems and some of the more popular clone copies
Over the production life of the Apple II series, more than eight countries and twenty or so leading edge PCB manufacturing plants were contracted to create Apple's product backbone, the Printed Circuit Board. It is the custom PCB that represents the foundation the design is built on, providing the electrical connectivity between the circuits and the mechanical support required to deliver reliability.
As the popularity and demand grew for Apple's products, their business model did as well. Maintaining PCB quality while successfully supplying demand and leveraging scale of economies were key, and Apple sought various PCB manufacturers around the world to produce this highly unique PCB component for each of its product's manufacturing lines. Each plant, although producing a technically compliant PCB part, has minor discrepancies that almost act as a signature to each plant's particular PCB manufacturing process. Each plant also places a unique identifier, manufacturing batch code and date on to every PCB they make. Differences, although very minor, are typically associated with characteristics such as a solder mask colour (dark green, light green or yellow), finish (gloss or matt), legend colour (white or yellow), HASL (the silver or gold finish on non-populated parts) and finished copper colour (traces being dark green [black oxide] or yellow [brushed copper]). All of these characteristics can actually make one Apple logic board appear significantly aesthetically different to another (although both assemblies are electrically and functionally identical). Even before popular IPC specifications had been set, Apple placed very high quality requirements on their PCB manufacturers. Presentation was paramount in Apple's eyes. The logo, printed on Apple boards from 1983, still exceeds the standard PCB production quality of silkscreening on boards by even today's standards, more than 30 years later. In this example, the high resolution silkscreen printing on the board would have been state of the art for PCB production in 1983. Many Apple collectors and enthusiasts can tell the difference and even have a preference for which finish and aesthetic look they prefer most. Listed below are examples of PCBs from Apple products, which detail their build spec and plant origins.