Image credit: BTW | RezTron | Communication Systems Solutions
Electronic manufacturing services (EMS) are companies that design, assemble, produce, and test electronic components and printed circuit board (PCB) assemblies for original equipment manufacturers (OEMs).
Electronic Manufacturing Services - How It Works
EMS companies may provide a variety of manufacturing services, including design, assembly, and testing. EMS companies may be contracted at various points in the manufacturing process. Some companies require only a design file from the customer before proceeding to develop the product, source the components from a trusted distributor, and assemble and test the product. Alternatively, EMS providers who specialize in assembly may require the customer to provide the design, the components necessary for manufacturing, and an assembled sample. EMS companies may provide additional onsite services, such as PCB etching, or provide these services through another contractor.
Electronic manufacturing involves different levels of automation, depending on the company and project. Companies that produce large runs of products typically use heavily automated manufacturing. Providers who specialize in prototypes or small production runs typically assemble PCBs manually to save the time and cost involved in setting up automated assembly equipment.
This video details one manufacturer's automated assembly process.
Video credit: Clear Automation
Design and Testing Services
Many service providers design and test electronic products in addition to manufacturing them.
Design services encompass several related actions that occur after determining a customer's specifications or product needs and before manufacturing or assembly takes place. The EMS company may first provide a product concept detailing the main objectives of the project and preliminary specifications. The company may do research by interviewing product users, consulting experts, and exploring existing related products. After these two steps occur, the product is then developed, visualized, and tested, and a prototype is sent to the customer for approval.
EMS companies may provide one or more types of product testing after completing a prototype or product run.
Agency compliance testing ensures that the product meets the safety and quality guidelines of a certain agency's standards.
Analytical laboratory testing assists in quality control, failure investigation, and research and development.
Automated optical inspection uses a computer to analyze a PCB to locate defects, including broken traces, excess solder, etching problems, or improper hole registration.
Environmental testing simulates a product's intended environment. Environmental tests may vary the environment's temperature, humidity, and vibration to test the product's resistance.
Functional testing simulates the assembly's normal function to test its overall operational characteristics.
In-circuit testing involves probing individual components within the circuit to test their operation.
X-ray testing uses non-destructive imaging techniques to provide a thorough analysis of an assembly.
Manufacturing and Production Capabilities
Electronic manufacturing companies may specialize in one or more areas of manufacturing technique and production size.
Electronics manufacturing encompasses several different types of electronic products.
Printed Circuit Boards
Printed circuit boards, or PCBs, are flat boards that hold electronic components. EMS providers populate PCBs with components to create printed circuit assemblies (PCAs), and may have the capability to work with several different types of boards. PCBs are assumed to be rigid and manufactured as a hard, inflexible board. Flexible PCBs can bend and accommodate flexible circuits used in instrumentation, automotive, and medical applications. Rigid-flexible PCBs are rigid boards with flexible interconnects.
EMS companies may also specialize in one of two types of PCB technology: through hole (THT) and surface mount (SMT).
Through hole technology involves mounting components by inserting their leads through holes drilled in the board. The leads are then soldered into place on the opposite side of the board. THT components are typically hand-soldered or wave soldered to a PCB in a production line.
Surface mount technology components are soldered to the top of the board, and are usually smaller and less expensive than THT components. From a manufacturing standpoint, modern pick-and-place equipment can mount SMT components quickly and accurately.
Left to right: through-hole connectors, SMT component on a PCB. Image credit: Samtec; Custom electronics
For more information about PCB fabrication, visit PCB Fabrication Services on GlobalSpec.
As its name implies, microelectronics deals with the manufacture of very small semiconductor components and includes flip chips and chip on board devices. Flip chips are integrated circuits (ICs) that connect to external circuitry using solder bumps deposited on the chip. They are often used in cell phones, pagers, and other small electronics. Chip-on-board (COB) devices involve bonding bare dies to PCBs.
Optoelectronic devices involve sourcing, detecting, or controlling light. EMS companies may assemble optical switches, fiber optic transmitters and receivers, and laser modules.
Radio frequency (RF) or wireless devices are frequently used in telecommunications and data transfer applications. EMS providers may assemble radio frequency identification devices (RFID) and other telecommunication and wireless technologies.
EMS companies may specialize in several different production levels and speeds, depending on their available equipment and capabilities.
Some providers build prototypes, which are early samples made to test a product's concept, following the design phase. Prototyping ensures that the product will serve its intended purpose after it is manufactured as part of a larger production run. Prototypes are often built with cheaper materials than those used in the production process. In the past, electronics manufacturers produced prototypes using breadboards and THT components, but the widespread availability of custom prototype PCBs now allows manufacturers to produce prototypes that closely mirror the intended product. Prototyping may occur multiple times at various points in the design and planning stages of a project.
EMS companies often specify their production volume capabilities. Although production volume statistics are relative, general guidelines can be specified:
Low volume providers produce small quantities, typically 1 to 100 products. Low volume is often similar to or synonymous with prototyping.
Medium volume providers are able to produce around 100 to 10,000 products annually.
High volume providers can produce more than 10,000 units annually.
Electronics manufacturers may also specify specialty production techniques, including quick turn production and cabling services. Quick turn manufacturers can assemble PCBs within a short time, usually 48 hours, after receiving all components. Cabling manufacturers attach cables to electronic assemblies.