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Questions relating to designing PCBs
By JoeHinkle
#165957
I've got my toaster oven and preparing to do my first board build.

I have some bypass caps on the bottom side.

Using the toaster oven --- I can reflow both top and bottom at the same time? Right??

Any comments or suggestions before my first attempt would be appreciated.

Thanks in advance.

Joe
By techy101
#165960
I've read opinions that the surface tension will hold the bottom components in place, though I've not had that work. On my first attempts with my oven I just did those by hand, but have now purchased some Loctite 3621 Chipbonder, which is a heat-curing adhesive made for the purpose. You put a dab along with the solder on those caps and reflow just that side. Once the oven activates the glue it will stay bonded when you flip the board over and reflow the other side.

I haven't actually had a chance to try it out yet though, so I can't vouch from actual experience.

Here's the product:
http://www.digikey.com/product-detail/e ... ND/2486663
By JoeHinkle
#165961
I've got 6 0805 caps under the micro.

Putting the bypass caps on the top side destroys any chance of doing a compact pin route. Micro is 1440 LQFP.

The surface tension of the solder is suppose to adhere them in place.

I am going to monitor and control both top and bottom heating elements independently to make sure both side flow at the same time.

If they fall off -- then I do them by hand.

I was hoping someone had some experience in this area.

Joe
By techy101
#165962
I wasn't saying to move them to the top side of the board. I was saying to reflow the board twice. Do it first with the side that the caps are on facing up, but add a bit of the chipbonder. Then do the other side; the epoxy will have already activated, and the components which are now facing down will be glued in place.
By waltr
#165963
techy101 wrote:I wasn't saying to move them to the top side of the board. I was saying to reflow the board twice. Do it first with the side that the caps are on facing up, but add a bit of the chipbonder. Then do the other side; the epoxy will have already activated, and the components which are now facing down will be glued in place.
And that is typically how commercial board assembly houses do it.