Although most of PCBs are produce and assembled as IPC-A-600/IPC-A-610 Class 2, such as consumer electronics, computer peripherals, telecommunication & wireless, IoTs, robotics, LED & lighting, test & measurement, industrial controls. But for same special area, IPC-A-600/IPC-A-610 Class 3 must be applied, such as automotive, medical, military, aeronautics, life support systems., etc. Military and aeronautics even requires IPC Class 3/A which is a higher standard than Class 3.

Here in Viasion, we can supply PCBs produced according to IPC Class 3 and IPC Class 3/A, to meet the highest standard in PCB industrial.

The main acceptance criteria for IPC-A-600 Class 3 PCBs

  • The minimum copper plating thickness in PTH wall are different:

IPC Class 2 PCB acceptance criteria:  PTH wall thickness>=20 um.
IPC Class 3 PCB acceptance criteria:  PTH wall thickness>=25 um.

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    • Minimum ring of PTH:

    IPC Class 2 PCB acceptance criteria:  Broken ring at 90 °or less.
    IPC Class 3 PCB acceptance criteria:  Min. Ring size: 0.05mm.

    • Copper conductor width

    IPC Class 2 PCB acceptance criteria:  Gap not over 30% of the minimum wire spacing
    IPC Class 3 PCB acceptance criteria:  Gap not over 20% of the minimum wire spacing

    • Hole wall copper plating voids:

    IPC Class 2 PCB acceptance criteria:  Cavity inside the hole wall acceptable under certain conditions. 
    IPC Class 3 PCB acceptance criteria:  Not accept any cavity inside the hole wall. 

    • Soda strawing in solder mask:

    IPC Class 2 PCB acceptance criteria:  Straw gap acceptable under certain conditions. 
    IPC Class 3 PCB acceptance criteria:  Straw gap is not allowed.  

    • Maximum wicking allowed in copper plating.

    IPC Class 2 PCB acceptance criteria:  Wicking not over 100 um.
    IPC Class 3 PCB acceptance criteria:  Wicking not over 80 um.

    The main acceptance criteria for IPC-A-610 Class 3 PCB Assembly

    • Hole wall filling by tin in PTH holes
    As for PTH holes, the main point is hole wall filling amount by tin. Hole wall filling amount required for through-hole pins, IPC class 2 are 50%, but for IPC class 3 will need 75%. Because the solder paste may be fragile when placed in small copper plated holes (PTH), so we advice the PTH size over 15 mils of components pins when you do the design. Then, there will have 7.5 mils space each side, that make the solder paste fill the hole wall more easier. Anyhow, PTH leads should be always needed be perfectly soldered, and always need to follow customer’s standards and requirements.

    IPC Class 2 PCB assembly acceptance criteria:  Hole wall filling amount over 50%.
    IPC Class 3 PCB assembly acceptance criteria:  Hole wall filling amount over 75%.

    • Wetting on SMT components

    IPC Class 2 PCB assembly acceptance criteria: tin is evident on the vertical surface of the SMD components
    IPC Class 3 PCB assembly acceptance criteria: min. Fillet height is 0.5mm, or 25 % solder + SMD component height 

    • Side overhang on SMD components

    IPC Class 2 PCB assembly acceptance criteria:  side overhang less than 50% of the component/pad area 
    IPC Class 3 PCB assembly acceptance criteria:  side overhang less than 25% of the component/pad area 

    • End joint width on SMD pads

    IPC Class 2 standard:  end joint width is min. 50% of the SMD component/PAD
    IPC Class 3 standard:  end joint width is min. 75% of the SMD component/PAD  

    • Side overhang on IC pins

    IPC Class 2 standard:  side overhang less than 50% of the pin with or min.0.5mm (whichever is less) 
    IPC Class 3 standard:  side overhang less than 75% of the pin with or min.0.5mm (whichever is less) 

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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.

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