There is a wide range of EMS companies, of all sizes and with very scope of activities. Different type of EMS can be divided by their size:
-Top Tier manufacturers
-Mid Tier manufacturers
-Bottom Tier local manufacturers
There are several other aspects to consider when selecting an EMS, including:
-The scope of activities offered by the electronic manufacturing services company;
-The range of certifications they secured;
-The areas where they are able to provide competitive costs;
-The technical capabilities they have;
-The strength of their production, procurement and quality assurance processes.
Scope of Activities
Some client will only need a printed board assembly (PBA) to be populated with components and soldered. Others will be seeking a full turn key service from sourcing of component to final assembly and testing. It is important to evaluate the scope of activity each EMS can offer reliably.
All EMS will offer some or all of the following activities:
-Sourcing of components as specified by customer (electronics, enclosures, wires and harnesses);
-Sourcing or fabrication of PCBs;
-Assembly of Printed Board Assemblies (PBA) with SMT or PTH/DIP;
-Testing of board (SPI, AOI, ICT, FT)
-Conformance coating and other special treatment;
-System assembly and testing
-Technical work such as cost improvement, ODM or variant management.
There is a wide range of standards and certification EMS companies can have. The most current are:
Areas where China EMS provide competitive costs
The total cost of PBA is mainly related to the cost of the Bill of Material (BOM). Only large EMS has strong cost advantages on component because of their purchasing power. Smaller companies do not always have the best component prices.
Still, China EMS have strong cost advantages in these areas:
-DIP/PTH manual insertion
-Testing of PBA and Systems, especially when tests require many steps like for mobile phones
System assembly using PBAs and plastic or metal enclosure
-Lower setup costs for small production batches
All these steps require skilled labor and China offers good value for buyers. It is important to understand where each supplier can bring cost advantages in the long run in order to develop a stable supplier-buyer business relationship.
We touched upon this a little in the scope of activity. Different suppliers will have different capabilities and it is important to ensure that they really master the techniques they claim to have:
-Precision of component placement on PCB;
-Type of components that can be placed and soldered (SMT, COB, Flexible PBA . . .)
-Type of test they can run: x-ray tests, fast in-circuit tests, advanced functional and environment tests ï¿½
-Number of PCB layers
-Range of instruments in the factory for specific tests
Strength of production, supply chain and quality processes
Capabilities need to be evaluated like for any supplier, as we described in a previous post: What should I look for during my visit? In particular, a few areas are really important to evaluate:
-Component sourcing, incoming inspection and storage
-Inventory and forecast balancing: some components have long lead time and it is important to understand how much of the balancing can be done by supplier and how much must be kept in house by the buyer
-QC records and analysis for each test and monitoring done.
Some suppliers also provide advanced capabilities such as
-Bar-code control process
-Full traceability from a specific delivery to production batch and incoming goods order.
This is clearly not an exhaustive list, but considering all these items will prevent buyer from making the wrong decision when selecting a Chinese electronic manufacturing services company.