What is acceptance criteria for PCBs?

Acceptance criteria for PCBs are specific characteristics, standards and requirements that PCBs must meet to achieve approval.

PCB acceptance criteria typically include- PCB thickness and dimension accuracy- PCB surface finish quality – PCB copper weight accuracy – PCB solder mask coverage, colour, and transparency – PCB silkscreen printing accuracy – Electrical performance testing, including continuity, isolation, and power integrity.

Meeting all PCB acceptance criteria is essential to ensure PCBs are of the highest quality and will perform as expected in their intended applications.  It will help minimize costly mistakes and redesigns while ensuring you get the most out of your PCB investment. A solid understanding of PCB acceptance criteria is essential for successful PCB production.

By far, the most widely accepted acceptance criteria for PCBs is IPC-A-600 standard. 

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    What is IPC-A-600 standard

    PC-A-600 is an international standard which outlines acceptable workmanship criteria for printed circuit boards.

    It is widely used across the PCB industry as a comprehensive set of requirements that must be met to ensure quality in the fabrication of circuit boards.
    IPC-A-600 is an essential guideline for ensuring that quality PCBs are manufactured and assembled every time. It is a critical resource in circuit boards and should be used by anyone involved in their production or inspection.

    IPC-A-600 is an invaluable tool for PCB fabricators, designers, assemblers and quality assurance professionals. The IPC-A-600 standard covers a wide range of topics, including bare material, copper plating, tolerances in PCB thickness & dimensions, any kinds of visual defects etc.

    What acceptance criteria for PCBs do we following in Viasion?

    Here in Viasion, we strictly follow IPC-A-600 Class 2 and Class 3 standards to make sure our PCBs are produces as the highest industry standards. Besides we will also inspect and delivery PCBs which meet customer’s special requirements, such as very tight tolerances in PCB dimensions, thickness, impedance etc.

    What are the main difference between IPC-A-600 class 2 and class 3

    The IPC-A-600 standard, developed by the IPC (Association Connecting Electronics Industries), is an internationally recognized standard for printed circuit boards (PCB).

    IPC-A-600 sets out requirements for accepting PCBs and defines a range of classes, from Class 1, Class 2, Class 3 to Class 3/A – based on the board’s visual and functional acceptability. 

    Aspects IPC-A-600 Class 2 IPC-A-600 Class 3
    Reliability
    Normal
    High
    Cost
    Normal
    High
    Copper Thickness
    >=20um
    >=25um
    Industry
    Normal industry and commercial products, such as consumer electronics, communications, LEDs,
    Highly reliable electronics such as automotive, medical, avionics, life support system
    Inspection Standard
    Lower standard in visual defects, such as voids, cavity inside the holes in holes, spot in solder mask, Conductor wire gap, ring around drill, etc
    High standard in visual defects, such as voids, cavity inside the holes in holes, spot in solder mask, Conductor wire gap, ring around drill, etc

    Generally speaking, IPC-A-600 Class 2 ensures that all customers can be confident that the IPC-A-600 class 3 boards they receive meet the highest levels of quality and safety.

    The edge/outline of the PCB

    Acceptance-criteria-for-PCBs-1 (1)

    Qualified:  Roughness of the board edge caused by burrs has not broken the edge.

    Acceptance-criteria-for-PCBs-2

    Qualified:  The inward infiltration distance of the notch/halo is ≤ 50% of the board edge spacing, and infiltration anywhere is ≤ 2.54mm.

    Acceptance-criteria-for-PCBs-3

    Unqualified:  The warpage of the board exceeds 0.75%.  

    Acceptance-criteria-for-PCBs-4

    Unqualified  There are continuous burrs on the broken edge.

    Acceptance-criteria-for-PCBs-5

    Unqualified  Halo and notch on the edge of the board is more than 50% of the spacing between the board edges, or more than 2.54mm.

    Acceptance-criteria-for-PCBs-6

    Unqualified:  Board edges and corners are damaged and delamination occurs.

    The surface of the PCB

    Unqualified:

    There are fingerprints on the surface of the board; corrosion of the copper surface affects the performance.
    Acceptance-criteria-for-PCBs-8

    Qualified:

    There is no indentation or indentation does not cause bridging between conductors; indentation does not make exposed burst fibers cause line spacing reduction to be less than 20%, media thickness to be equal to/more than 0.09mm.
    Acceptance-criteria-for-PCBs-9

    Unqualified:

    The distance between external inclusions, garbage particles and the nearest conductor has approached 0.125mm. The size has exceeded 0.8mm.

    Unqualified:

    The scratching of the solder mask causes copper exposed, beyond the above provisions.

    Acceptable:

    Non-sensitive scratching of the solder mask does not cause copper or metal exposed; the appearance is not obvious.
    Acceptance-criteria-for-PCBs-11

    Unqualified:

    The indentation makes exposed burst fibers cause line spacing reduction to be more than 20%, media thickness to be less than 0.09mm.
    Acceptance-criteria-for-PCBs-12

    Unqualified:

    There is cracking, delamination and blistering on the board surface.

    Solder mask

    Unqualified:

    The solder mask appears off-set. On pads with a pitch greater than 1.25mm, the solder mask appears to be more than 0.05mm off; on pads with a pitch greater than 0.65mm and less than 1.25mm, the solder mask appears to be more than 0.025mm off.
    Acceptance-criteria-for-PCBs-14

    Unqualified:

    There is wrinkling of solder mask ink which makes copper exposed.
    Acceptance-criteria-for-PCBs-15

    Unqualified:

    The solder mask exposure is poor; pads are less than 20% of the size.

    Unqualified:

    There is blistering and oil drop from solder mask, more than two sizes of 0.25mm per side or greater than 25% of the circuit spacing.
    Acceptance-criteria-for-PCBs-17

    Unqualified:

    The stripping of the solder mask makes the copper exposed; the solder mask ink is broken off more than 50% of the distance from the nearest conductor.
    Acceptance-criteria-for-PCBs-18

    Unqualified:

    Characters on the PAD are blurred and illegible.

    Copper trace

    Unqualified:  The gap in the circuit is greater than 20% of the width of the conductor; the circuit is scratched so that the copper is exposed.

    Acceptance-Copper-trace-2 (1)

    Unqualified:  The circuit is too thin, less than 20% of the width of the conductor.

    Acceptance-Copper-trace-3

    Unqualified:  The warpage of the board exceeds 0.75%.  

    Unqualified  The circuit has rough burrs which are greater than 20% of the conductor spacing.  

    Acceptance-Copper-trace-5

    Unqualified  There is a short circuit.

    Acceptance-Copper-trace-6

    Unqualified:  Poor circuit patching affects electrical performance.

    Vias/Holes

    Unqualified: The broken holes and solder rings are more than 90°.

    Acceptance-Vias-Holes-2

    Unqualified:

    Blocked holes make it impossible to mount components.
    Acceptance-Vias-Holes-3

    Unqualified:  The warpage of the board exceeds 0.75%.  

    Unqualified:

    There are lumps in the hole; the diameter of the hole is less than the minimum value specified in the procurement documents.
    Acceptance-Vias-Holes-5

    Qualified:

    The wrong property of the hole affects the assembly of the components.
    Acceptance-Vias-Holes-6

    Unqualified:

    There are missing drilling holes, extra drilling holes, and misplaced holes.

    Solder mask

    Unqualified:

    There is no tin on the solder pads; the dewetting area of the pads is greater than 5%.
    Acceptance-Solder-pads-2

    Unqualified:

    The indentation and edge defects of BGA pads are more than 10% of the pad diameter; defects are more than 20% of the circumference of the connection pad.
    Acceptance-Solder-pads-3

    Unqualified:

    There is ink on the pad, affecting the soldering performance.

    Unqualified:

    The scratch notch of the pad exceeds 20% of the size.
    Acceptance-Solder-pads-5

    Unqualified:

    There is oxidation, leakage of plating, dump plating, etc. on the pads, which affects the soldering performance.
    100

    Unqualified:

    Pads appear warped, defective.

    Carbon ink, blue peelable mask, high-temperature mask

    Unqualified:

    There is a short circuit of carbon oil, affecting performance.
    Acceptance-Carbon-2

    Unqualified:

    Blue glue covers other processing areas.
    Acceptance-Carbon-3

    Unqualified:

    There is a broken hole on the blue glue.

    Unqualified:

    There is leakage of high-temperature glue.
    Acceptance-Carbon-5

    Qualified:

    High-temperature glue covers the holes used for mounting components.
    Acceptance-Vias-Holes-6

    Unqualified:

    There are missing drilling holes, extra drilling holes, and misplaced holes.

    Outline/Shape

    Unqualified:  The size of the external dimensions exceeds the required value or tolerance of the procurement documents.  

    Acceptance-Outline-Shape-2

    Unqualified:  V-CUT causes damage to copper; V-CUT appears off-position.  

    Acceptance-Outline-Shape-3

    Unqualified:  The V-CUT is missed; the depth of the V-CUT does not meet the required value of the procurement documents.

    Unqualified  Extra slotted holes are drilled; the processing with CNC milling machine is missed in some parts of the board; the profile processing with CNC milling machine is not thorough; the profile processing with CNC milling machine causes copper to be exposed; the dimensions of the board do not meet the required values in the procurement documents.  

    Acceptance-Outline-Shape-5

    Unqualified  The V-CUT is too deep causing the board to break; the depth of the V-CUT exceeds the depth required by the procurement documents.  

    Acceptance-Outline-Shape-6 (1)

    Unqualified:  The beveled edge of the gold finger is missing; the beveled edge is damaged so that the copper of the gold finger is exposed; the depth and angle of the beveled edge do not meet the required value of the procurement documents.  

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