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PCBpro - IPC Inspection

Index : PCB Library : PCB Glossary : IPC Inspection Guideline

In an effort to insure quality for our Customers, PCBpro has adopted an inspection program using the IPC-600F as its guide. The IPC-600F, which is the pictorial guide for the IPC-6012, is an industry standard for classification of the Printed Circuit Board quality level.

The following chart shows the IPC-A-600F (or its supporting document IPC-6012) inspection item and its call-outs. To the right shows how we have elected to inspect for those items *.

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

Characteristic	IPC-600F Guideline *	PCBpro Inspections
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-HAL and Final inspection
Dewetting	Ground planes and traces: allowed Solder connection areas: max. 5% (Class 2, 3)	Post-HAL 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-HAL 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 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-HAL inspection
Mask coverage	See 3.8.1	Post-HAL inspection
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-HAL inspection
Mask in holes	Allowed only in holes in which are not to be soldered.	Post-HAL inspection
Mask registration		Post-HAL inspection
Mask thickness	Visual coverage; no thickness requirement	Not checked unless specifically required by drawing
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 mask)
Min. ann. ring NPTH	Class 2: No breakout allowed. Class 3: annular ring not less than .006, isolated 20% reductions allowed (Table 3-5)	Final inspection
Min. ann. ring-internal	Class 2: 90° breakout allowed Class 3: .001 minimum annular ring (Table 3-5)	Process control using micro sections, design check at front end to ensure 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. Class 3: .002 minimum annular ring, except on vias (90° breakout allowed).	In-process inspection (after etch, before mask)
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-HAL 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-HAL 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-HAL 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

* We seek to use the standard’s classification and defect determinations to maintain a “Class II” quality level. Other aspects in the IPC-6012 have been deviated from in an effort to keep our internal costs down. We have elected instead to use our own system to maintain quality. Our quality program, sampling plans, coupon use, record keeping, and use of outside labs is different than the IPC-6012.