Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


gift

Views: 1360

RusH

#44370

Lead free parts on a leaded assembly | 5 October, 2006

We are having significant issues with lead free parts on leaded assemblies. Particularly grainy and non-wetted solder joints. Does anyone have any solutions.

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

#44371

Lead free parts on a leaded assembly | 5 October, 2006

Good afternoon.

From what it sounds like is that the solder joins are not getting hot enough or if it Au, then the increase in the Au content of the joint is increasing the melting point of the final solder joint. To some extent, this will also happen if the leads are pure Sn.

Grainy appearance can also be caused by an extended cool down. A quicker cool down will cause the formation of a smaller grain structure of the alloy.

I'd be interested in more details about your process and project. Such as surface finish, component finish and profile. If you could provide me with these details, we can solve this together.

Should you have any further questions, please contact me. My contact information is below.

Regards,

Mario Scalzo, SMT CPE Technical Support Engineer - Southwest Region mscalzo@indium.com 315-797-0253

reply »

RusH

#44373

Lead free parts on a leaded assembly | 5 October, 2006

Mario,

Thanks for your response. We are building a leaded assembly with hot air leveled Sn/Pb pads on the PCB. In one case the component is a 7.5X5.2X1.8 wire wound ferrite inductor with Au/Sn leads. The second component is an 0808 Tantalum cap, again Au/Sn. The assembly contains a few BGA processor chips with limited reflow temperatures of about 220C. The solder is an Alpha 63/37 OA paste.

Robert

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

#46633

Lead free parts on a leaded assembly | 12 January, 2007

Several things to check. Are you reflowing towards higher temps for the no-lead parts? If so are you using a 63/37 paste? If so you are buring your flux off too early. Get a solder paste designed for lead free parts on a leaded baord. There are several out there. The solder still melts at 183 C but the flux is designed for higher temps.

reply »

StikNPeel™ Rework Stencils

 Reflow System