Hi George, Thank-you for your comments and feedback. The solderability test (Dip and Look) was done using flux. The solder paste intended for use in production is eutectic tin/lead. Noted your comments regarding dip and look test. We will follow up with surface mount simulation test.
Regards, Mumtaz
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Tuesday, June 21, 2016 5:31 PM
To: Forum, TechNet; Mumtaz Bora
Subject: Re: [TN] laminate package wetting issues on ENIG surface
Hi Mumtaz,
Your statements are a little confusing. You indicated you fail solderability when you Dip-&-Look test the QFN with Sn63/Pb37 solder paste but pass solderability when you Surface Mount Process Simulation test the QFN with SAC305 solder paste. The Dip-&-Look test is supposed to be conducted by applying flux to the QFN pads and then dipping it into molten solder. This test is not intended to be done using solder paste. If you really meant that the QFN fails Dip-&-Look testing with Sn63/Pb37 solder but passes Surface Mount Process Simulation testing with SAC305 solder paste then my comment would be that it is not surprising that the QFN fails the Dip-&-Look testing because this is an inappropriate test for QFN packages. If you look at Section 5.3 in the JEDEC standard you will see that it indicates "The Dip and Look test is also inappropriate for BGA’s." This section should really indicate that the Dip-&-Look test is inappropriate for BGS's, QFN's and similar surface mount components. The solderability failures of these packages is due to physical issues associated with the Dip-&-Look test and not necessarily because the interconnection parts are not solderable. What I would do is to perform a Surface Mount Process Simulation test on the QFN using Sn63/Pb37 solder paste and I think you will see that the results will be completely different then the Dip-&-Look test.
Regards,
George
George M. Wenger
Failure Signature & Characterization Lab LLC
609 Cokesbury Road, High Bridge, NJ 08829
(908) 638-8771 (Home) (732)-309-8964 (Cell)
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________________________________
From: "Mumtaz Bora" <[log in to unmask]<mailto:[log in to unmask]>>
To: [log in to unmask]<mailto:[log in to unmask]>
Sent: Tuesday, June 21, 2016 7:42:26 PM
Subject: [TN] laminate package wetting issues on ENIG surface
Hello Technet team,
We have a laminate based QFN package with ENIG plating on terminations. Using lead based paste Sn63/Pb37, we fail solderability test per JESD22B102E (dip and Look test) and also per J-STD-002 method B (dip and Look test). However, we passed reflow solderability test using lead free paste (SAC 305) per method JESD22B102E . Due to product requirements, we have to use eutectic Sn63/Pb37 solder paste. The reflow oven is convection air . If anyone had this issue and can share some insight or inputs will be much appreciated.
Thank-you,
Mumtaz
858-795-0112
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