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I’m trying to solder my TSSOP-16 chip to the DIP adapter. I’m planning to apply solder paste to the adapter’s pads, put the chip on the adapter and then use my kitchen oven to melt solder paste and connect those two together. I have a few questions:

  1. Should solder paste be precisely applied to each of adapter’s pads without going over to neighboring pad or is it okay to just smear solder paste on all pads?

  2. Should solder paste completely cover adapter’s pads or should i put just enough paste so that SMD chip’s leg om adapter-pad is covered?

  3. At what temperature and for how long should I keep this in my kitchen oven?

Here’s an image of my adapter, little smd chip and solder paste: enter image description here

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    \$\begingroup\$ Don't use your kitchen oven. Get a toaster oven and use it for reflowing solder and never use it for food. \$\endgroup\$ – DKNguyen Oct 22 '19 at 19:07
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    \$\begingroup\$ I wouldn't use the kitchen oven - lead contamination. \$\endgroup\$ – Leon Heller Oct 22 '19 at 19:08
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    \$\begingroup\$ Those are pretty easy to solder by hand with an iron, a little flux and some skill with "drag soldering" and you should be able to get it on there pretty easy without the paste. \$\endgroup\$ – Ron Beyer Oct 22 '19 at 19:39
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    \$\begingroup\$ @RonBeyer Yeah I would just solder those by hand with drag soldering. Probably with a 2-3mm chisel or hoof tip. \$\endgroup\$ – DKNguyen Oct 22 '19 at 19:46
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    \$\begingroup\$ And not only is your kitchen oven unsafe from a food-safety standpoint, most ovens don't get as hot as you need them, they heat unevenly, and the temperature can vary wildly (since ovens are on-off control). If you really want to use solder paste, you can still use a hand-iron to do it, I'd avoid the oven altogether, otherwise you need to worry about ramping, soak times, and let-down times. \$\endgroup\$ – Ron Beyer Oct 22 '19 at 19:51
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As others have said, don't use an oven that you put your food in!! Lead poisoning is no joke.

If you are looking for the easiest and cheapest way to do reflow soldering at home, I recommend getting a cheap hot air gun with adjustable airspeed and temperature control. They can be had on amazon for less than $50, and allow you to repair existing boards as well as reflow new ones.

When applying the solder paste for this package, a single thin bead vertically across all of the pads should be fine. Once you heat things up, the solder will flow to the pads and shape up nicely. If you apply too much solder, bridges will form between the pads; you can clean those up with a soldering iron and some solder wick.

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  • \$\begingroup\$ The proper tool is NOT a "hot air gun" but rather a "hot air rework tool". If it looks like an evil hair dryer, it is for stripping paint, not soldering. Something made for soldering has a base with controls, a handpiece, and a cradle for the handpiece to rest in which has a magnet/reed switch to put it in cool down mode when placed back in the cradle. \$\endgroup\$ – Chris Stratton Oct 22 '19 at 22:35
  • \$\begingroup\$ Yes, my bad--that's what I meant. Thanks for the correction! \$\endgroup\$ – CoolNamesAllTaken Oct 24 '19 at 0:46
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That chip would be far more easily soldered with an iron, not to mention doing so avoids all the issues with contaminating your food oven and work area.

Tin one one paid in a corner. Heat that pad and place the chip. Use an eye loupe to verify alignment.

Solder the opposite corner, and verify alignment again.

Now solder all the pins. Don't worry about the fact that the iron is bigger than the pin spacing, you'll probably be heating several at once, but surface tension and perhaps extra flux will take care of making the right connections.

If you get a bridge that won't clear with flux and re-heating, use ultra fine solder braid (or larger braid cut down).

If you really don't want to do this with an iron (or need to fix a mistake), use a hot air tool. They are quite inexpensive now, and far more controlled than an improvised reflow oven. When used on gentle flow without a reducing tip they won't even blow away 0402 components (though used with a reducer, they sure will!).

If you have to use solder paste, use only lead free. Leaded wire solder may be one thing, but solder paste just sticks to things. Even with lead free paste, use disposable gloves and alcohol wipes for cleanup. To use paste properly you would need to start with a blank board and a stencil for the part footprint. Anything you do without that is likely to be inferior to careful use of wire solder and an iron. Even replacing a previously installed chip is likely to go better by using an iron to get an even amount of solder on the pads (a binocular microscope is a huge help), fluxing, placing the new chip in the flux, and heating with a hot air tool.

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  • \$\begingroup\$ The flux in lead free solders (at least the SAC variety) is very aggressive (far more than the flux in SnPb solders) and effective fume extraction is more important than ever. \$\endgroup\$ – Peter Smith Oct 28 '19 at 12:03

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