Electronics Forum | Wed Jun 13 15:56:35 EDT 2007 | ck_the_flip
I experienced this with a high-mass capacitor. I was able to turn down the bottom-side convection (around 50�C lower than each of the top-side heaters), and able to NOT lose any parts. I got the bottom-side part just slightly over liquidus, and min
Electronics Forum | Mon Apr 14 16:21:58 EDT 2008 | ck_the_flip
Bottom-side SMT parts CAN and DO go liquidus during the 2nd reflow cycle. It could be that there was enough variability between the 2 different lot code PCBs to cause the parts to fall off. Remember wetting force determines surface tension (the abi
Electronics Forum | Fri Mar 02 09:08:25 EST 2007 | samir
There is a formula that determines whether a component will fall off during a 2nd reflow. It takes into account the grams (weight) of the component and the total surface area of the solder joints. I don't know this off the top of my head, but it's
Electronics Forum | Mon Jun 19 18:17:43 EDT 2006 | PWH
We are now running SMT ROHS assemblies. We are losing some upside down parts in the reflow oven when running the 2nd side. These are parts that do not fall off the leaded version. Anybody else having problems with this? What are you doing to stop
Electronics Forum | Wed May 06 13:44:58 EDT 1998 | Chrys
| Dear Freinds, | DOES ANY ONE OF YOU WILL BE KIND ENOUGH TO GIVE SOME INPUT ON DOUBLE SIDE REFLOW OF COMPONENTS WHAT ABOUT BOTTOM SIDE COMPONENT HOLDING DURING 2ND SIDE REFLOW? ANY IDEA OTHER THAN USING SLDERPASTE WITH OFFSET MELTING POINT, EPOXY DI
Electronics Forum | Thu Jun 23 08:58:00 EDT 2005 | Irene Taylor
We are defining a new assembly process for a double sided card that has 26 BGAs on the top side and 14 BGAs on the bottom side. We currently have one double sided BGA board with one BGA per side and have to epoxy one BGA (35mm X 35mm - 352 ball count
Electronics Forum | Sat Aug 07 09:32:54 EDT 2010 | scotceltic
We have a Large LGA package (40mm X 40mm) that we are trying to process on a double-sided assembly. problem is the only space we have for it is on 1st side processing side. Therefore we have worries about falling off in the oven during the 2nd side
Electronics Forum | Wed Jun 16 15:44:52 EDT 1999 | Jagman
| WOULD LIKE TO DO RELOW OF 2 SIDED SMT BOARDS. USUALLY THE BOTTOM SIDE HAS RESISTORS AND CAPS ONLY. WHEN THE BOTTOM OF THE BOARD HEATS UP, THE PARTS ARE FREE TO MOVE AND ONLY SURFACE TENSION WILL KEEP THE COMPONENT FROM FALLING OFF. | CAN BOARDS BE
Electronics Forum | Tue May 24 13:18:43 EDT 2011 | leemeyer
We had a Quad 4C that was fitted with a dispensing nozzle. It was perfect for jobs like this. Place the 1st component in the paste, add a dot or 2 of paste to the top of that part and then place the 2nd component on top. I beleive that you may be ta
Electronics Forum | Mon Oct 15 08:15:41 EDT 2012 | scottp
Is the designer's concern that the parts will fall off when hanging upside down during reflow? We've been doing this for decades and our test if we think a part is marginal is to glue a 2nd (and sometimes 3rd) part to the back and send it through re
