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April 2016

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From:
Lawrence Dzaugis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Lawrence Dzaugis <[log in to unmask]>
Date:
Wed, 13 Apr 2016 14:50:45 -0400
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When using lead HASL the critical dimension is the copper plated hole size. This can be held tighter than the finished hole size. The HASL can be deformed easily in comparison.

 I have not used lead free HASL for press fit. Immersion Sn and Ag can be used, ENIG was common, IBM used organic finishes. You must develop your own force profiles for insertion. I have used force controlled presses to arbor presses. It depends.

"Stadem, Richard D." <[log in to unmask]> wrote:
>Sn63 HASL coating is the best finish, provided you are allowed to use it. The lead is a lubricant.
>No matter what the chosen finish is, the most important variable to control is the finished hole size after plating and the tolerance.
>The ability to perform  the proper initial drill consistently and obtain the initial hole size within a tight tolerance after drilling (repeatability and control over drills), and obtain the final hole size after plating varies from PWB fabricator to PWB fabricator. The selection of the right fabricator is extremely important for PWBs that will use press-fit or compliant-lead connectors.
>The eyelid should be completely under the top surface of the hole. The connector design controls the depth of the eye with respect to the shut height of the connector, ie, if fully pressed in such that the insulators or connector body are fully seated to the PWB surface, the eye should be at least 95% fully into the hole. The ability to obtain that is affected by the resistance variable, the amount the pin is allowed to bend upwards during insertion, and this is an attribute of the press tooling and press setup. The amount of resistance brings into play the finished hole size, the surface hole finish, and how the stars line up on the day you decide to press them in, and the relationship of the press operator's mother to his/her father on the day of conception. So "Godd Luck" with that.
>Odin
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Mattix, Dwight
>Sent: Wednesday, April 13, 2016 11:59 AM
>To: [log in to unmask]
>Subject: Re: [TN] Press Fit Pins guideline, Second Time Around
>
>Realized long time ago, the only way out is to do your own due diligence. Good luck with getting funds approved for your own reliability demonstration, hole wall deformation x-section analysis and pin to pwb  insertion/retention force testing. 
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
>Sent: Wednesday, April 13, 2016 4:13 AM
>To: [log in to unmask]
>Subject: Re: [TN] Press Fit Pins guideline, Second Time Around
>
>I feel the pain......    There is not relief in sight.....
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Lum Wee Mei
>Sent: Tuesday, April 12, 2016 7:26 PM
>To: [log in to unmask]
>Subject: Re: [TN] Press Fit Pins guideline, Second Time Around
>
>I have been asking the same questions even directly to the press-fit manufacturer themselves and there is no conclusive answer. Except to drown myself in the piles and piles of information from their website and often end up going round and round.
>
>To quote from Gerry : " Godd hunting"
>
>Regards,
>~wee mei~
>________________________________________
>From: TechNet [[log in to unmask]] on behalf of Gerry Gagnon [[log in to unmask]]
>Sent: Wednesday, April 13, 2016 1:55 AM
>To: [log in to unmask]
>Subject: Re: [TN] Press Fit Pins guideline, Second Time Around
>
>Hi Victor,
>
>Second time is the charm.
>
>Press fit pins are highly engineered and have many specifications associated with them.
>Each press pin manufacturer's design tends to be unique as a lot of them are patented.
>
>The best answer to your questions is to tell you to find out the specific press pin manufacturer's part number for the pin that you are dealing with, go to their web site, and get the drawings and specifications for the specific pin you want to know about.
>
>I think you will be surprised at the level of detail you will receive for your questions plus the attributes you have not asked for ....... yet.
>
>Good hunting.
>
>Gerry
>
>________________________________________
>From: TechNet on behalf of Victor Hernandez
>Sent: Tuesday, April 12, 2016 11:59 AM
>To: [log in to unmask]
>Subject: Re: [TN] Press Fit Pins guideline, Second Time Around
>
>Fellow TechNetters:
>
>My initial inquiry, 2011, did NOT yield any useful information. Therefore, I pose the same question again in hope that additional reader will provide comments and/or their experience with Press Fit Pins.
>I look forward to hear from the readers.
>
>What is the acceptable depth of the main eye lid with regards to total board thickness? I have seen a variety of depths used.
>What is the preferred raw board surface finish? Again, I have seen a variety.
>
>Victor,
>
>From: Garcia, Rigo (GSFC-370.0)[ARES CORP] [mailto:[log in to unmask]]
>Sent: Wednesday, January 27, 2016 11:28 AM
>To: Hernandez, Victor G
>Subject: RE: Press Fit Pins guideline
>
>Thanks!
>
>Rigo
>
>"The future belongs to those who believe in the beauty of their dreams" - Eleanor Roosevelt
>
>From: [log in to unmask] [mailto:[log in to unmask]]
>Sent: Wednesday, January 27, 2016 12:21 PM
>To: Garcia, Rigo (GSFC-370.0)[ARES CORP]
>Cc: [log in to unmask]
>Subject: RE: Press Fit Pins guideline
>
>Rigo,
>
>I did NOT get any concrete guidelines and/or specification for Press Pin Fit leads. The specs that are out there are confidential.
>
>Victor,
>
>-----Original Message-----
>From: Garcia, Rigo (GSFC-370.0)[ARES CORP] [mailto:[log in to unmask]]
>Sent: Wednesday, January 27, 2016 11:08 AM
>To: Hernandez, Victor G
>Subject: RE: Press Fit Pins guideline
>
>Hi Victor,
>
>Did you get an answer to your question?
>
>I'm interested because we are looking into qualifying press fit connectors for flight hardware and don't know of any specs that provide requirements for the process.
>
>Best regards,
>
>Rigo Garcia
>
>"The future belongs to those who believe in the beauty of their dreams" - Eleanor Roosevelt
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
>Sent: Monday, January 25, 2016 1:40 PM
>To: [log in to unmask]
>Subject: [TN] Press Fit Pins guideline
>
>Fellow TechNetters:
>
>What is the current IPC guideline/specification for insertion depth of Press Fit Pins. I aware that the Press Fit Pins configuration might vary a little, just as well as board thickness. What is the acceptance criteria I should look for visually and during x-ray imaging.
>
>Victor,
>
>
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