“DFM” is the abbreviation of design for manufacturing. PCB design for manufacturing refers to the design of PCBs need to ensure that products are functionally good firstly, and at the same time, the fabrication process is simple, fabrication efficiency is high, fabrication quality is high, fabrication defect rate is low and PCB cost is low.
“DFA” is the abbreviation of design for assembly. PCB design for assembly refers to the design of PCB Assembly need to ensure that products are functionally good, and at the same time, the assembly process is simple, assembly efficiency is high, assembly quality is high, assembly defect rate is low and the overall cost is low.

Why do we need DFM/DFA

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    What free DFM do we offer


    There are many types and brands of material in the world, so we are not not possible to prepare all the material in advance. So we will suggest suitable alternative to our customers if we do not have specified material in stock. But if customer can not acceptable any kind of alternatives, we can also buy specified types/brand as customers’ design.


    We will produce as customer’s stack-up normally, but sometimes we had to suggest another stack-up. There are three main reasons: firstly, we do not have the specified core/prepreg thickness or copper thickness; secondly customer specified stack-up cannot meet controlled impedance volume; thirdly customer specified stack-up has failure risk. Of we will only start production as the new stack-up under customers’ approval.

    Panel Design

    Although most of the times, customer will supply panel drawing or advise. But sometimes, customers do not give us any clue for panel panel. As an one stop PCB and PCB assembly supplier, we know PCB with panel frame is very difficult to assembly. So we also also advise customer a suitable panel drawing.

    Improper panel since the edge connectors are inside of the panel which is not good for chamfer on the gold connectors.


    In PCB manufacturing, there are some critical tolerances, such as overall thickness tolerance, outline tolerance, copper trace width/space tolerance, impedance value tolerance, copper plating thickness tolerance, surface finish thickness tolerance. Our CAM engineer will carefully all these tolerances in the drawing and ask questions if we cannot meet. If there is no tolerance in your drawing, we will also produce as IPC-A-600 Class 2 standards.

    CAM Design

    Copper trace

    Broken trace
    The etched characters are reverse characters. For example, the bottom layer is positive and the top layer is negative. In some cases, the pros and cons of etching are a basis for judging the wiring level.
    The distance from pad to board edge is too small, which may lead to damage to pads in profiling process.

    The thermal pad overlaps with the isolating pad, and the continuity cannot be determined.

    Isolation area of The power and ground layer are too small, the connecting line of the same network.

    Distance between the circuit is too small.

    The distance betwen the inner layer isolation pads is too small.

    Dummy copper pads should be added on big area free from copper, to avid bow & twist.
    Drill on the separate area

    Solder Mask

    Forget to keep ficucial marks free from solder mask.
    Solder mask opening on fiducial is too big.
    Extra solder mask opening on pad/trace.
    Edge connectors are not fully free from solder mask.


    Although silkscreen errors are very critical, but they may brings us troubles in PCB assembly process. Besides, unclear, incomplete or crowd silkscreen is not good in appearance. So our CAM engineers will also check and raise questions if there is any errors. The normal errors are: silkscreen on pad, crowd together, out of board edge, size too small, overlapped, negative words on top side etc.


    Vias and PTH holes overlap. The hole attribute is NPTH in drawing, but there are pads/ring around the drill.

    No relative notes for special holes. Some times specials holes can be be imported by EDA software, so the should be marked in the drill drawing.

    The drill size is the same size as the pin of the PTH components.

    Blind and bured vias

    Blind and buried are designed to reduce the PCB size and enhance the function of the PCBs. Although we are capable to produce any layer via HDI PCBs, but we always advise symmetrical structure which is easier to produce, and also reduce the possibility of bow & twist.

    What free DFA do we offer


    We will do a thoroughly DFM for PCB before productions, mainly including the file check for the following aspects.
    • Material
    • Stack-up
    • PCB panel
    • Holes: PTH, NPTH,
    • Tooling hole, Mounting hole
    • Fiducial marks
    • Solder side clearance
    • Component clearance
    • Copper connection
    • Solder mask color
    • Silkscreen
    • UL logo/PCB vendor
    • PCB panel
    • Surface finishes advise

    BOM Check

    Stated roughly, the important functions of PCBA are described below.

    The parts on the BOM do not fit the foot pad or drill on the PCB.
    components part number is not clear or not complete, we will ask customer and suggests the correct part number if possible.

    Alternative advise

    Some times there are parts which are obsolete or very long lead time, we will suggest alternative if possible, and will only use them in production when customer approved.
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    Viasion Technology is your trusted partner & one-stop shop for PCB fabrication, components sourcing, PCB assembly and electronic manufacturing. With more than 16 years of experience, we have been supplying high-quality PCBs with competitive pricing for 1000+ customers worldwide. Our company is ISO9001:2015 Certified & UL Listed, and all our products are 100% E-tested and inspected by AOI & X-RAY to meet the highest industry standards. So please get an instant quote from our sales team now, and we will take care of the rest.