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PIHR Inspection Criteria

Bob Willis

#6625

PIHR Inspection Criteria | 17 May, 2001

Here is a copy of a draft document on PIHR Inspection I have jotted down on a flight to Scotland yesterday, any comments suggestions etc ? I have already most of the photos for the standard but as you know there is nothing in the IPC document it just says make up your own criteria so here we go. Which was what they decided to do when I first raised the issue with the new IPC610 document two years ago. As many people expressed an interest some time back on PIHR this may be of interest.

Look forward to your comments suggestions. Pin In Hole/Intrusive Reflow Inspection Standards Solder Paste Deposit

Satisfactory

Solder paste deposit is complete and conforms to the same size as the stencil aperture dimensions and may be printed onto the surface of the solder mask and over the through hole

Acceptable

Solder paste deposit conforms to the aperture in the stencil design there is some evidence of minor paste displacement

Unacceptable

The solder paste deposit is incomplete and does not conform to the designed aperture in the stencil. There is evidence of paste smudging on the surface of the board.

Pin-In-Hole/Intrusive Reflow Inspection Standards Component Pin Insertion

Satisfactory Component pins have been inserted through the solder paste with the body of the component seated on the board surface with no paste displacement

Acceptable

Component pins have been inserted with minor lead displacement, this is acceptable provided that the minimum 1mm lead protrusion on the base of the board is visible.

Unacceptable

Component pins have been inserted but leads have failed to be inserted with the minimum lead protrusion on the base of the board. Pin-In-Hole/Intrusive Reflow Inspection Standards Component Pin Insertion

Satisfactory

Component pins have been inserted through the solder paste. Paste is visible on the tips of the pins prior to reflow

Acceptable Solder paste is visible on the tips of component pins and in adjacent through holes. The filling of adjacent holes where pins are not included on the component are not mandatory.

Unacceptable

Component pins are not visible on the base of the board after assembly of the component pins Pin-In-Hole/Intrusive Reflow Inspection Standards Component Pin Insertion

Satisfactory

Component pins have been inserted through the solder paste. Paste is visible on the tips of the pins prior to reflow. Paste may also be visible around the pad this is dependent on which side the paste is applied.

Acceptable

Solder paste is visible on the tips of component pins and in adjacent through holes. Minor evidence of paste displacement from the print deposit is possible when component pins are inserted from the opposite side of the board Unacceptable

Complete displacement of the solder paste deposit from the board due to poor paste tack is unacceptable

Pin-In-Hole/Intrusive Reflow Inspection Standards Soldering Standards Satisfactory

Soldering of the through hole pins shall show satisfactory wetting between both the land and termination Acceptable

The degree of hole filling varies on the pins but meets the minimum hole fill of 75% of the plated through hole board thickness. Evidence of base material on the pads or pin is acceptable Unacceptable

The minimum hole fill of 75% of the board thickness has not been achieved Pin-In-Hole/Intrusive Reflow Inspection Standards Soldering Standards Hold Down Features Satisfactory

Soldering of the location/hold down pins shall show satisfactory wetting between both the land and termination. Base material on the non paste side of the board may be seen Acceptable

Soldering of pins show wetting between the pin and land. The hole is not completely filled with solder and base material on the pad is visible Unacceptable

Pin-In-Hole/Intrusive Reflow Inspection Standards X-Ray Inspection of Solder Joints Satisfactory

The x-ray image shows a complete fill of the plated through hole with positive solder fillets around the component pins Acceptable

The image shows a reduced hole fill but still exceeds the minimum requirement of 75% fill of the plated through hole. There is evidence of minor voiding in the solder fillet Unacceptable

The x-ray image shows excessive voiding in the barrel of the hole, although unlikely to cause failure it illustrates the reflow profile/process is unacceptable.

Pin-In-Hole/Intrusive Reflow Inspection Standards Assembly and Soldering Defects

Unacceptable

Solder balls on the surface of the resist after reflow are normally associated with the compatibility of the solder resist. Unacceptable

Solder ball of solder build up on the tips of component pins is normally associated with incorrect profiling of the printed board assembly Unacceptable

Incorrect insertion of the component pins is normally associated with damage to the leads or inappropriate component packaging Unacceptable

No or incomplete reflow of paste is normally associated with incorrect profiling of the board or excessive time/ temperature during preheat of low ultra low residue pastes Unacceptable

No or incomplete reflow of paste is normally associated with incorrect profiling of the board or excessive time/ temperature during preheat of low ultra low residue pastes

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#6633

PIHR Inspection Criteria | 17 May, 2001

Hi Bob

Still getting the cushy jobs, eh? [Tennent's and McEwans are two of my favorites. "Ahh, Beer! My one weakness...my Achilles Heel, if you will..." Homer J Simpson Quote 89/114]

Under "Acceptable" for "Pin-In-Hole/Intrusive Reflow Inspection Standards Component Pin Insertion", what do you mean by "minor lead displacement"?

On the second "Pin-In-Hole/Intrusive Reflow Inspection Standards Component Pin Insertion", can we have a different title?

On the second and third "Pin-In-Hole/Intrusive Reflow Inspection Standards Component Pin Insertion", can these be combined?

On "Satisfactory" for "Pin-In-Hole/Intrusive Reflow Inspection Standards Soldering Standards", shouldn�t there be a minimum hole fill statement? Or are you thinking that it�s not required because of "satisfactory wetting between both the land and termination" statement? If so, it should be clearer.

On "Pin-In-Hole/Intrusive Reflow Inspection Standards Soldering Standards Hold Down Features", "Unacceptable" would be expected to address now-wetting and poor hole fill situations, of course.

On "Pin-In-Hole/Intrusive Reflow Inspection Standards Assembly and Soldering Defects", are you really bringing anything to the party here? Shouldn�t these connections meet the requirements of the assembly?

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Michael Parker

#6637

PIHR Inspection Criteria | 18 May, 2001

I will start with the statement that I think it is great that we have the ability to solder SMT components that emulates wave soldered components. With that in mind, I would want to find acceptance criteria to be similiar, regardless of the solder media source.

I am a bit unsure why you spent so much effort on pre-reflow acceptances. It seems that a majority is meaningless if the final result is OK. I am believing that pre-reflow inspection is primarily used for process engineering, it would not be practical for production.

Your post reflow criteria all sound reasonable. I would like to suggest that you expand on the barrel fill and voiding. You stated: "The x-ray image shows excessive voiding in the barrel of the hole, although unlikely to cause failure it illustrates the reflow profile/process is unacceptable."

There are more valid causes than the reflow profile, although the major cause may be in fact the reflow profile.

Otherwise, this is a good draft and should prove useful if adopted by the community at large.

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