Electronics Forum | Wed Mar 28 11:29:49 EST 2001 | gcs
I've used below: WEIGTH OF COMPONENT IN GRAMS ---------------------------- TOTAL PAD MATING AREA IN SQUARE INCHES GRAMS PER SQUARE INCH MUST BE EQUAL/GREATER THAN 30 FOR SECONDARY MOUNTING.
Electronics Forum | Thu Oct 15 11:04:28 EDT 2009 | spitkis2
Thanks Jim. Pressing the QFN into paste was what I thought of, just wasn't sure if it would cause solder paste to be pressed outside the pad area and possibly bridge with an adjacent pad. Do you recall the ratio of paste coverage to the pad area?
Electronics Forum | Tue Sep 11 09:13:01 EDT 2001 | davef
Like most things in electronic assembly, this is not astrophysics. People have pasted boards, placed components, turned the board up-side down, run the board through a reflow oven, and generalized about which components: * Fall off the board. * Don
Electronics Forum | Mon Apr 28 09:34:37 EDT 2003 | davef
Double sided weight of component to total pad mating area ratio: 30 gm per sq inch (50 mgm per mm2) Go to the sites of these consultant-people for additional background [I'm not sure exactly where on these sites to look, but both are laden with goo
Electronics Forum | Mon Jun 30 16:35:13 EDT 2003 | davef
Hi Steve We don�t double reflow this part. We wouldn�t consider it without a fixture or some other support. You know that sound, the almost involuntary sound that patrons in a restaurant make when a waiter drops a glass or a tray? It�s kind of an
Electronics Forum | Sat Mar 21 12:19:51 EST 1998 | David Pick
I have read somewhere of a ratio of component weight vs. surace contact area rule for double reflow soldering. This ratio is the maximum weight vs. surface tension to hold a component on during the second reflow. With this number, a person could weig
Electronics Forum | Tue Jun 17 08:52:39 EDT 2003 | russ
Aspect ratio = width of aperture divided by height. E.G. 6 mil stencil at 9 mil wide = aspect ratio of 1.5. Value should be 1.5 min. Area ratio - use when length and width of pad are roughly same dimension like for BGAs and 0805 and smaller R-nets
Electronics Forum | Fri Dec 11 16:06:18 EST 1998 | Michael Allen
G, You'll find at least one old thread in this Forum on dual-reflow if you do a search. I found one dated April 7, '98 (searched on "reflow"); this particular thread includes a discussion about the maximum weight-to-surface_area for successful dual
Electronics Forum | Thu Jun 02 14:57:36 EDT 2011 | davef
We don't expect properly soldered first-side DPAKs to fall from the board during second-side reflow. The ratio of weight to solder surface area for a DPAK is 1.32 gm per in^2, which is well within the limit of 44 gm per in^2. [Search the fine SMTnet
Electronics Forum | Mon Oct 04 11:28:46 EDT 1999 | Mark D.
Does anyone have a list of component types that can be put on the bottomside of a doublesided reflow board that will not fall off during the second pass (Or on the otherhand, a list of components that will fall off)? This would be a list of parts tha
