What does Electronics manufacturing services (EMS) mean?

- Apr 10, 2017-

Electronics manufacturing services (EMS) is a term used for companies that provide PCB Assembly, Box Build, test, and return/repair services for original equipment manufacturers (OEMs). The concept is also referred to as electronics contract manufacturing (ECM). Due to maintenance cost, availability of materials, quality, and speed, many companies in EU, North America, choose to build electronics in China, where Shenzhen is a center.

 PCB Assembly

 The process to populate / stuff a bare printed circuit board with electronic

components to form a functional printed circuit assembly(PCA), sometimes called a "printed circuit board assembly" (PCBA). 

In through-hole technology, the component leads are inserted in holes surrounded by conductive pads; the holes keep the components in place. 

In surface-mount technology (SMT), the component is placed on the PCB so that the pins line up with the conductive pads or lands on the surfaces of the PCB; solder paste, which was previously applied to the pads, holds the components in place; if surface-mount components are applied to both sides of the board, the bottom-side components are glued to the board. In both through hole and surface mount, the components are then soldered. In both component leads are then mechanically fixed and electrically connected to the board by soldering. 

Often, through-hole and surface-mount construction must be combined in a single assembly because some required components are available only in surface-mount packages, while others are available only in through-hole packages. Another reason to use both methods is that through-hole mounting can provide needed strength for components likely to endure physical stress, while components that are expected to go untouched will take up less space using surface-mount techniques. 

  High volume production is usually done with a "Pick and place machine" or SMT placement machine and bulk wave soldering or reflow ovens to achieve high efficiency and consistency. 


During and after the PCB assembly, a variety of tests may be executed at Maxway to ensure high quality and consistency:

SPI - Short for Solder Paste Inspection, a test for solder paste volume, critical step to prevent solder errors in PCB assembly.

Pre-Reflow AOI - Automated Optical Inspection (AOI) before reflow process, a system to identify component and solder joint defects.

Post-Reflow AOI - AOI after reflow process

FAI - Short for First Article Inspection, at Maxway, FAI is a must before mass production, when there is engineering change or change of production lines.

In FAI, the AXI - Automated X-Ray Inspectiontest could be required. AXI inspects structural solder faults of non-visible joints such as area-array packages (BGA, CSP, Flip Chip), parts under RF shielding, and some special connectors.

ICT - Abbreviation for In-circuit Test, which checks and detects current leakages in the circuitry, defective components and manufacturing defects.

FCT - Short for Functional Test, a test to identify functional defects within a printed circuit board assembly.

At Maxway, the AOI and FCT coverage is 100%.

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