MELF component short togehter

After reflow, Are the end terminals of the melf packages touching or is it a paste bridge? What type of reflow are you using? IR?... Convection?

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Good job clarifying things.

So, your MELF are just rolling off the pads. So much for the rocket scientist that talked you into those �V� shaped apertures, eh? [Or taking it the other way: Wow, just think how bad it would be if they weren�t working so wonderfully.]

Every stinking one of those stupid MELF has a mind of its own, anywho. Feeble though it may be. They just wander around. They end-up here. They end-up there. Not a care in the world. For the two micocents that your buyer saves in material cost, you end-up repaying 200 times over in heartache.

Here�s what�s happening: * Paste melts first at the corners [In your case, the �apexicies� of your triangular paste deposits.] * Edges of your paste deposit melt next. * No wetting action gets going on the MELF teminations to overcome any surface tension with the molten solder, because it�s too early in the process. * Ball bearings on the surface, round component, domed shape of the HASL, and no paste on the outer edge of the pad to slow anything down; you got whoops. [The component does not have to move very far before it is no longer contacting the stickiness of the paste.]

Consider: * Using a �U� shaped aperture. * Turning down the blowers in your oven. * Convincing yourself that your transport is running smoothly. * Determining that you are placing components properly. * Making sure the in-bound and out-bound curtains on your oven are not dragging across the board. [Although, you would have noticed this previously, wouldn�t you? Sorry. Hey, when you do this stream of conscious thing, sometimes it works sometimes it doesn�t.] * Gluing the rotten little @#%## in place. [Although, this may not be the smartest thing you could do, depending on the subsequent processing and product use.] * Using a board fabricator with a flatter HASL process. * Relaying-out the MELF pads to compensate for the doming of the HASL. * 0.8mm clearance between two MELF SB plenty of room.

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