DFN soldering process

Thread Starter

Janis59

Joined Aug 21, 2017
1,179
Nothing to ask guys, sorry, have only to tell.
So, today had to learn a DFN tablet soldering process. Damn tricky, but as technologies progress, must have to go along em.
Thus the biggest problem is that they arent solderable by normal methods.
They have a thermal pad in the middle, what must be well soldered without of any touch possibility.
They have a numerous contact feets covered completely by body, thus untouchable.
First I just applied an air solder (hot air blower) and failed of course. Tablet was dead after procedure.
So, after a bit reading how the things must be done I applied the thermoregulator to the 150 C, wait an about 5...10 seconds and then set the temperature above to 260 C, keep a 4...5 seconds and Voila!.
So, the 150 regime gives the time to tablet to warm up mildly to avoid the crystall thermal shock.
That is extra important.
Im happy with the result.
Use this experience if count it useful.
Thats all. How radio code says to say, Over! and then Out!.
 

jpanhalt

Joined Jan 18, 2008
9,413
Right, reflow soldering can be done by pre-tinning all the pads, but getting the right amount of solder on the pads by eye can be tricky. Solder paste with a stencil has proved to be more reproducible when several devices need to be so attached.
 

Thread Starter

Janis59

Joined Aug 21, 2017
1,179
DL324 - Yet with a difficulcy I would label me a hobbyist after my first pcb I produced somewhere around 1969, and about 50% of life had worked in this or that near the circuit fabrication/design/repair etc etc.
 

jpanhalt

Joined Jan 18, 2008
9,413
Unfortunately, very few hobbyists are going to have access to the equipment that makes rework easier.
My Wagner HT400 (about $25 now, lower when they sold the straight version) made such a repair possible. Not as easy as soldering an SOIC, but certainly not the hardest soldering job I have done. It's all a matter of protecting parts you don't want to remove or reflow (aluminum foil works great) and watching what you are doing. Steady hands are not required.
 
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