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Leadfree component plating on Sn/Pb paste



Leadfree component plating on Sn/Pb paste | 21 June, 2003

Most of the capacitors & resistors supplier have implemented Leadfree finished on their components and like it or not, most of the PCBA house already using them in their process. I just got a notice from my component supplier telling me that they will start sending leadfree capacitors to us and I told them no problem as I see most of the time, temperature of these small caps and res always higher compare to those big components during reflow. Some of them can reach up to 235 - 250 Deg C.

Can someone tell me what is the problem I could potentially see, when running this using Sn63/Pb37 paste ? What is the different between reflowing NiPd plating versus Leadfree Sn/cu plating, be it wetting finished & reflow profile requirement ?

Thanks in advance.

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Leadfree component plating on Sn/Pb paste | 23 June, 2003


No Major issue using lead-free plated components in tin-lead as long as Sn/Bi is not the finish. I think some customer might be worried about low melting phase.

More voiding may be seen in case of ceramic capacitors used with tin-lead. It is well documented in published literature. Recommend spending some time on web based information. lot of it is available

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Leadfree component plating on Sn/Pb paste | 30 June, 2003

Any further input guys ? What is the effect of reflowing lead free component with eutectic solder paste, as far realiability is concerned ?

Input is very much appreciated.

thank you

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Leadfree component plating on Sn/Pb paste | 2 July, 2003

Title : SOLDER JOINT RELIABILITY OF Sn-Ag-Cu BGA COMPONENTS ATTACHED WITH EUTECTIC Pb-Sn SOLDER PASTE Author : Fay Hua et al. Author Company : Intel Corporation Date : 01/01/2003 Source : Journal Of Surface Mount Technology, Volume 16-1 Abstract : In transition to Pb-free electronics, component suppliers may need to carry dual- line production of Pb-free and Pb-containing components. This could cause extensive logistic problems in manufacturing. A total conversion to Pb-free components could be a solution for this problem. Therefore, solder joint reliability of Sn-Ag-Cu BGA components attached with eutectic Pb-Sn solder paste needs to be addressed.

This paper presents the results of solder joint reliability evaluation of VFBGA (very fine pitch ball grid array) and SCSP (stacked chip scale package) Pb-free packages attached to printed circuit boards (PCBs) with eutectic Pb-Sn pastes. The packages were assembled under various reflow profiles using standard Pb-Sn assembly conditions. Peak reflow temperatures of 208�C and 222�C with a soak profile or a direct ramp up profile was used. The assemblies were subjected then to board level temperature cycling (-40�C to 125�C, 30 minutes per cycle) and drop testing. Detailed failure analysis is also presented.

Key words: solder joints, reliability, BGAs, Pb-free, Pb-Sn and Sn-Ag-Cu solder compatibility

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Leadfree component plating on Sn/Pb paste | 8 July, 2003


The answer in general is no mixing of Lead Free with Sn/Pb solder. If you look at reliability data, failures after stress tests and then SEMs, failures occur at grain boundaries inside the joint. Lots more happens.

By the way this mixing happens sometimes by accident and it is an industry concern depending on reliability goals and stress tests.

For you case, I don't know, so I would have your reliability person, or your customer's reliability person examine the situation.

YiEngr, MA/NY DDave

This message was posted via the Electronics Forum @

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Leadfree component plating on Sn/Pb paste | 8 July, 2003

YiEngr, MA/NY DDave: Please excuse the coarse language ... horse patoey!!!

Companies been building reliable products with no-lead components and Sn/Pb solder for years. For example, TI has been shipping parts with leads whose solderability is protected with Pd for over ten years.

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