PCB Manufacturing - Assembly

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Electronic Contract Manufacturing (ECM) is a is term used for companies that offer contracts for electronic assembly for another company. For instance, instead of attempting to manufacture complex circuit boards themselves OEM companies often outsource their manufacturing operations to ECM companies. In effect Contract manufacturing providers do not post their brand name on any product, and both design and the brand name belongs to the OEM.

The birth of the CM industry was marked by IBM's entry into the PC market in 1981, which started a trend to outsource what was considered outside core competence. This sparked a feedback cycle of outsourcing, giving the ECM companies a way to obtain better economies of scale. Also, many OEMs sold off their production units to ECMs. For instance Swedish telecommunications manufacturer Ericsson sold seven plants in Sweden to Flextronics and Solectron in 1997. It is believed that this development has in general led to a shift in market power from OEMs to large ECMs, and has led to a rapid centralization of the CM industry. The key ECM companies today are Foxconn, Solectron, Flextronics, Tresmine (Australia), Sanmina-SCI, Celestica, EE Technologies, Jabil Circuit, and Benchmark Electronics mainly operated from North America and Taiwan.

As ECMs grew larger, many of them developed into EMS (Electronic Manufacturing Service) companies to offer a broader spectrum of services in addition to manufacturing. Today the trend continues even further, with many EMS becoming what are now called Original Design Manufacturers, offering complete electronic products for companies such as Wal-Mart, skipping the OEMs altogether.



Baking is a bit more complicated than many people realize. There are
baking recommendations for pre- and post-dry pack based on level and
package thickness. Pre-baking is used to prepare components for dry
packing, while post-baking is used to recondition components after floor
life expiration. Review and follow the time/temperature recommendations
for baking in J-STD-033. Baking temperatures can decrease lead
solderability by oxidizing the leads or causing excessive intermetallic
growth. Do not store components in an oven at baking temperature.
Remember, high-temperature trays can be baked at 125ÂC, while
low-temperature trays cannot be baked at temperatures higher than 40ÂC.

IPC post-bake recommendations after floor life has expired are: 

Package thickness less than or equal to 1.4 mm: For levels 2a through
5a, bake time ranges from 4 to 14 hours at 125ÂC, or 5 to 19 days at 40Â

Package thickness less than or equal to 2.0 mm: For levels 2a through
5a, bake time ranges from 18 to 48 hours at 125ÂC, or 21 to 68 days at

Package thickness less than or equal to 4.0 mm: For levels 2a through
5a, bake time is 48 hours at 125ÂC, or 67 or 68 days at 40ÂC.