In PCB assembly process, there are many steps and process is underway, the CM (contract manufacturer) want to make sure no may cause circuit board manufacturing (DFM) design problems, this is the CM should perform PCB DFM inspection, to ensure the right to make PCBA,

PCB DFM check: the first step in manufacturing PCB
When first received contract manufacturers design data, should be a thorough design review, CM will depend on how to deal with data designers choose to send data which format,
The received data in PCB design CAD database format will directly into the engineering review, the received data in other format must be imported or converted into CM tools, this process takes longer and lower reliability, which is why CM would rather get the cause of the original CAD database, but if the CM used the PCB design file format is compatible with all tested HuaQiu DFM, designers do not need to consider issues, in addition, if the CM eventually made any design change, they can more easily in the raw data format,
CM component engineer will check bom, find not recommended for manufacture, delivery time is long or the end of life (EOL) parts, at the same time, CM problems DFM design engineer should check whether the data, including the signal integrity, manufacturability and testability,

Potential problems and solutions of DFM
In CM of the component during the inspection, the inspection sheet on the parts with the main component matching supplier inventory database, the database will be constantly updated, and provide real-time data for parts availability for a component engineer, according to their conclusion, they will spare parts to replace any Suggestions, if can't find an exact match parts (such as the production has been halted parts), they will recommend functionally similar parts,
At the same time, the function of the design engineer is reviewing the design performance, if can improve impedance control wiring, for circuit board materials and the change of the layer stack Suggestions, they will also check the placement of components and wiring, to improve the signal integrity,
At the same time, CM manufacturing engineers check the assembly and testing of the circuit board, these problems may affect manufacturing, they are looking for some items include:
? Parts spacing: too close to the distance between the components to automatically take put the machine problems, and make the rework is difficult, in wiring connector placed incorrectly can lead to system is difficult to use,
? Position and rotating components: parts placement will affect circuit board welding, before the wave, the larger parts will be ahead of smaller parts, and lead to bad solder joints,
? Chip components pad size: incorrect chip components pad size or due to line with wider and bonding pad size may lead to different reflow soldering during these uneven heating pad, this may lead to erect, chip components in the end this situation is called "made a hit,"
? Acid trap: when cleaning from the board, the chemical etching, the walk line with acute wiring can be hard, lead to the line width is smaller than expected width,
? Use too much drill bit optimization: certain design size, should be combined to reduce the cost of PCB manufacturing,
? Bonding pad between the lack of resistance welding layer: this can lead to solder bridge, and could make should not connect two solder short circuit together,
? Testability: it covers many fields of PCB design, from the edge of the component to the plate spacing, for on-line testing of spot welding plate full coverage, if required, it also includes for PCB build or modify test fixture,
Upon completion of all design reviews, CM will prepare a report on the board by DFM check, at this point, the designer can correct on your own, also can ask CM's engineering personnel to assist to finish the work,
Because of the above projects can all through the HuaQiu DFM testing and obtain the relevant optimization advice, therefore, the proposal before send design documents to CM, design engineers can advance through HuaQiu DFM software testing of DFM and optimize the problems in design documents, it can greatly reduce the time cost of communication with the CM loss, so as to improve the efficiency of the entire development project,