Intrusive Reflow Process (侵入式回流過程) [复制链接]

I have seen the following disscussion in some SMT forum, perhaps we could have further discussion

Question:
What are the limitations of the intrusive reflow process?

Replied:
The amount of solder that the process is capable of applying is the biggest limitation. I believe that solder paste is only approx. 50% metal by volume. When connectors are soldered in intrusive reflow, often the stencil is "overprinted" to get more solder. In certain applications such as multi-row (3 or 4 rows)or if the connector is very close to another component, overprinting of the stencil is not an option. The connector lead pitch is also a very important factor in the intrusive reflow process. Solder preforms or solder flux bearing connectors will deliver more solder volume than the intrusive reflow process.

Intrusive Reflow Process is take the PTH component to the SMT process.
This is very useful. But how can we make enough solder paste for the component?  

This topic recall my memory and bring it back to 10 years ago ... ever provided such a Pin in Paste DFM proposal for a very popular financial calculator at US called HP 12C, you'll find an intrusive reflow process builds in the keyboard PCA for the only one through hole component - battery clips if you have chance disassemble a HP 12C calculator, the pattern is designed by Sky :)

Introduce intrusive reflow process, the big concern like sofa floor bro mentioned: the solder paste volume! Insufficient solder paste volume will bring you big headache, solution is simple, DOE, engineers always do DOE, and you need find your way out, right? Lots of factors we need care about: through size vs pin size, annul ring pattern vs stencil opening/thickness, a step up and step down stencil is highly recommended, you may also have chance to face other issues like paste drop when printing/flux drop when reflow if solder paste volume not well optimized, etc... however, when all of these negative problem solved, it will become very stable, and less operations! Less costs!

Another better solution is introduce solder preform for intrusive reflow process, now lots of soldering company provide solder perform total solutions, it's simple and stable but expensive :)

I can't remember more as it really past too long time, here's a good stuff from Cookson Electronics for your guys reference, enjoy: Intrusive reflow Process.pdf

There's an expert of Pin in Paste in our forum, who is named 阿红, the moderator of SMT123 column, he has rich experience on intrusive reflow process as it once run on IBM riser card for several years at his previous served company, he will be a very good consultant on this topic.

Oh My God!

Bro, you have been designing in xx since 10 years ago, but still remember the 12C calculator

This is  very good information which will be important for me to learn intrusive reflow process.
Thank you for your generosity.

引用第4楼水之缘于2010-01-27 22:49发表的 :
This is  very good information which will be important for me to learn intrusive reflow process.
Thank you for your generosity.

Hello! This is not only for you to learn, but also for discussion!
haha....

SKYLEE:
There is question about your information. It's about how do you calculate "Solder fillet volume". Where is  the data(0.215/0.2234 )come from? And what is meaning for?

Vf = Solder fillet volume
• Vf = (0.215r2) x (0.2234r + ra) x 2π
– r = (solder pad diameter - pin diameter) / 2 = 0.787 mm
– ra = (length x width/π)0.5 (for rectangular pin), Radius of
pin (for round pin), = 0.254 mm.

tks.

Bro, Sky do not be a good data champion for many years :)

Sorry for I can't answer your question in such details, you may want approach to golden333 for more details of the document since it was quoted from his attachment in this thread: http://bbs.smthome.net/read-htm-tid-77200.html, maybe he has the contact of the author.