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Inspection Guidelines

In an effort to insure quality for our Customers, Sunstone has adopted an inspection program using the IPC-A-600 Rev F as its guide. This industry specification is the pictorial guide for the acceptability of printed boards.

The following chart shows the IPC-A-600F (or its supporting document IPC-6012) inspection item and its call-outs. The Sunstone inspection column gives the Sunstone method of compliance.

IPC (Institute of Interconnecting and Packaging Electronic Circuits) publishes the IPC-A-600 Rev F pictorial guide.

*** Please note that the asterisk items are not rejectable if design review plus is not selected.

* We seek to use the standard’s classification and defect determinations to maintain a “Class II” quality level. We have elected to use an adapted inspection system to maintain production quality. Our quality program, sampling plans, coupon use, record keeping, and use of outside labs is different than the IPC-6012.

Characteristic IPC-600F Guideline * Sunstone Inspection
Board edges
  • Haloing and nicks maximum .100" or 50% of distance to nearest conductor, whichever is less.
  • No metal burrs; must be clean cut.
  • Final inspection
Bow and twist
  • General 1.5% max.
  • SMT boards 0.75%. max.
  • Final inspection
Conductor thickness
  • Table 3-9 (external)
  • Table 3-8 (internal)
  • One coupon per multilayer job micro sectioned
  • Sample of panels PTH copper thickness after copper plating (surface plating inferred from PTH plating)
Copper plating thickness, minimum in holes
  • Class 2, avg. .0008" , thin spots .0007"
  • Class 3, avg. .001", thin spots .0008" (Table 3-2)
  • Sample of panels PTH copper thickness after copper plating
Copper plating voids
  • Class 2 - One Cu void allowed per hole in not more than 5% of the holes.
  • Class 3 - No Cu voids allowed.
  • Shall not exceed 5% of hole length or 90° of circumference (Table 3-3)
  • 100% visual inspection after etching·
  • One coupon per multilayer job micro sectioned
Delamination/blisters
  • Evaluated in accordance with IPC-A-600
  • Class 1 now same as Class 2, 3 (2.3.3)
  • Evidence of delamination in micro section now refers to 2.3.3 instead of being automatically nonconforming (3.1.4)
  • Post-final surface finish inspection
Solder Dewetting
  • Ground planes and traces: allowed
  • Solder connection areas: max. 5% (Class 2, 3)
  • Post-final surface finish inspection
Finish plating voids
  • Class 2 - Three solder voids allowed per hole in not more than 5% of the holes.
  • Class 3 - One solder void per hole in not more than 5% of the holes.
  • Shall not exceed 5% of hole length or 90° of circumference (Table 3-3)
  • Post-final surface finish inspection
Foreign inclusions
  • Evaluated in accordance with IPC-A-600, except no maximum dimension specified (3.3.2.1)
  • In-process inspection (after etching, before mask)
Gold thickness
  • Class 2 - min. 30µ"· Class 3 - min. 50µ"· Solderable gold - 30µ" maximum.
  • Beta-backscatter or XRF measurement on sample after gold plating
Hole location
  • As specified on procurement document.
  • Not specifically checked, unless critical dimensions are noted on the master drawing; controlled by PM on drill machine
Hole sizes
  • ±.004" for plated through holes, ±.003 for non-plated through holes, +.003 / - hole size for vias, unless otherwise specified by customer
  • Sample at Post-final surface finish inspection
Solder Mask coverage
  • See 3.8.1
  • Post-final surface finish inspection
Solder Mask cure & adhesion
  • No tackiness
  • Blisters/delamination: 2 per side, max. .010 in, does not reduce spacing by more than 25%
  • Soda-strawing is now defined as applying to DFSM only (2.9.9)
  • Post-final surface finish inspection
Solder Mask in holes
  • Allowed only in holes in which are not to be soldered.
  • Post-final surface finish inspection ***
Solder Mask registration  
  • Post-final surface finish inspection
Solder Mask thickness
  • Visual coverage; no thickness requirement
  • Not checked unless specifically required by drawing
Solder Mask touch-up
  • Touch-up material specified (IPC-A-600F 2.9.1)
  • Final inspection
Measles/crazing
  • Evaluated in accordance with IPC-A-600
  • Measles acceptable for all except high voltage applications [not defined] (2.3.1)
  • Crazing spec. now same as delamination except 50% of distance between conductors may be spanned; also now shows pictures of crazing (2.3.2)
  • In-process inspection (after etch, before solder mask)
Min. ann. ring NPTH
  • Class 2: No breakout allowed.
  • Final inspection ***
Min. ann. ring-internal
  • Class 2: 90° breakout allowed
  • Process control using micro sections (selecting the design review option ensures design is within capability). ***
Min. external ann. ring - PTH
  • Class 2: 90° breakout allowed except at junction of pad and trace, where .002" minimum is allowed.
  • In-process inspection (after etch, before mask). Selecting the design check option ensures design is within capability). ***
Nomenclature (silkscreen)
  • Refers to IPC-A-600 for legibility requirements Marking ink on surface mount lands no longer nonconforming (IPC-A-600F 2.8.3)
  • Final inspection ***
Nonwetting
  • None allowed
  • Post-final surface finish inspection
Pink ring
  • Acceptable (3.3.2.6)
  • In-process inspection (after etch, before mask)
Pits and voids in base material
  • Acceptable if no larger than 0.8 mm [.03 in] and no more than 5% of board area
  • In-process inspection (after etch, before mask)
Plating adhesion
  • Tape test required (slivers coming off with tape is not cause for rejection)
  • In-process inspection (after etch, before mask)
Plating cracks
  • See Table 3-7 (basically none allowed)
  • In-process inspection (after etch, before mask); One coupon per multilayer job micro sectioned
Resin fill of blind/buried vias
  • Buried vias shall be at least 60% filled with resin (3.3.14)
  • One coupon per multilayer job micro sectioned
Routing tolerances
  • As specified on procurement document.
  • Final inspection; sample checked per customer drawing or default to ±.010
Spacing reduction
  • When not specified on the customer's documentation, 30% allowed for class 2; 20% allowed for class 3.
  • In-process inspection (after etch, before mask)
Tenting (via holes)  
  • Post-final surface finish inspection (when required) ***
Tin/lead, solder coat
  • Unfused tin-lead: min. .0003"
  • Fused or HAL: coverage and solderable.
  • Sidewalls do not have to be covered.
  • Post-final surface finish inspection; solderability process control on multilayer coupons
Trace width
  • Class 2, 3: When not specified on the customer's documentation, 20% max. line loss, additional 20% for isolated defects
  • In-process inspection (after etch, before mask)
Weave exposure and exposed/disrupted fibers
  • Acceptable for Class 1, 2, 3 as long as minimum conductor spacing is met.
  • In-process inspection (after etch, before mask)
Weave texture
  • Not addressed
  • N/A