Hello Christopher, IPC-4552, Specification for ENIG process does not specify a value for your question below. IPC suggests a minimum of 2 uin at four sigma below the mean; the typical value is 3 to 5 uin to provide good solderability to the Nickel layer within 1 year after the PCB fabrication. In the past, we experienced brittle solder joints with gold that was 12 uin thick. The parts fell off the assembly when it was knocked against a rigid surface such as the top surface of a table. If you can not find a good answer to your question then you may decide to create a DOE to model the relationship between the gold thickness and the hardness of the solderjoint. This would be a good project for an undergraduate engineering student! Hope this helps, Paymon Sani -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Christopher Nash Sent: March 26, 2007 11:42 AM To: [log in to unmask] Subject: [TN] Gold % Hello all, what is the IPC standard for the acceptable level/percentage of gold that can be consumed into a solder joint before gold embrittlement becomes an issue? Christopher J. Nash Mid-West Technical Support Engineer Indium Corporation of America Phone #: (315) 853-4900 x7521 Fax #: (315) 853-1000 www.indium.com -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Monday, March 26, 2007 11:33 AM To: [log in to unmask] Subject: Re: [TN] Press-fit Soldering Jumper mods can be made to standard compliant press-fit pins. However, unlike conventional pin-through connectors, you may not be able to rework (to remove) the connector should you ever need to. This is because standard solder removal methods such as wicking or solder suckers will not be able to remove every bit of solder where the compliant pin makes contact with the hole wall. Do not think that if you apply solder sparingly, you will not fill the hole and thus will not solder the compliant pin to the hole wall. If either the connector pin or the hole has any tin or tin/lead finish, simply touching a solder iron to the pin will be enough to solder the pin to the hole wall by reflowing the plating finish. But if you have to add the jumper, make sure the assembly has passed all electrical testing first. I am assuming you wish to put the jumpers on the solder side of the assembly. If, however, you wish to solder to the top side, then wrap and solder around the pin up away from the pad (if possible), and perform soldering only to meet the wrap-and-solder criteria, where the wrap must be a minimum of 3/4ths of the way around the pin, the soldering must be such that the lead contour is visible, and the insulation of the jumper begins a maximum of one wire diameter from the solder joint. A heatsink clip should be positioned where the pin enters the pwb to prevent the plating from getting hot enough to reflow, if needed. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Barr Sent: Monday, March 26, 2007 11:07 AM To: [log in to unmask] Subject: [TN] Press-fit Soldering Hi All, Engineering wants to solder a few jumper wires to press-fit pins on production boards. I am not completely comfortable soldering to press-fit pins and want to get input from others because there appears to be conflicting information between previous posts on this subject and IPC-610. I have read concern that the heat from soldering (hand soldering in this case) may compromise the press-fit connection - the theory being that the hole is already physically deformed and under some degree of stress by design of the press-fit pin and that heat may produce additional unintended stress. Since we are soldering a jumper wire the entire hole will not be filled and there will be a limited amount of heat introduced. Having never seen rework wires soldered to press-fit pins on production boards, I don't know if this is really a risk. Has anybody done this? The connector vendor is not willing to comment because they don't have information about this, so that adds to the unknown. The second issue I have read about is that the design of the press-fit connection prohibits the formation of a properly wetted solder interface between the pin and plated through hole. Since we are talking about a solder connection to connect a jumper wire to end of the pin and not for an electrical connection of the pin to the board I don't think this applies to our case. On the other hand, IPC-610 does have a section (4.3.2.1) that gives criteria for soldering press-fit pins so they must think it is OK. It states that press-fit pins are not intended to be soldered, but if soldering is required it gives criteria. So, my quandry is...is soldering jumper wires to press-fit pins a risk or not? Thanks in advance for any and all help. 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