Hoping to try soldering VQFN package TPS7A regulators using this very cheap mini hotplate, reviews on the tube seem ok just for single small PCBs.
Any one have experience with hotplates like these?
Also recommendations for 138 C paste and no clean flux, leadfree is the main option it seems at the temp range.
Any one have experience with hotplates like these?
Also recommendations for 138 C paste and no clean flux, leadfree is the main option it seems at the temp range.
My suggestion is to hand solder but the lands/pads need to be large enough to put the iron tip on without disturbing placement.
The other option is stencil/ paste/ hot air
The problem I see with a hot plate is the dwell time being way too long and possibly damaging the device
The other option is stencil/ paste/ hot air
The problem I see with a hot plate is the dwell time being way too long and possibly damaging the device
use the hotplate to support and preheat the board till 100degrC. then manually solder with leaded solder and tip temp at 340degrC. use flux
That's a good tip about the pads, thanks. Will try to implement that into the layout. The other option is obviously a hot air rework station, the hotplate was a cheap looking method.
Thanks for the suggestions chaps.
Dynalo Mini? Good luck. The boards I built were done with 3oz. copper. There were enough of the pads going to the ground plane that I never was able to successfully solder these, but I didn't have a hot plate. I also didn't have a stencil for that package, but did try hot air as well. I know a couple of guys on HC were able to get them soldered on, but I used Amb's TO-220 style regulators instead on the ones I built. Doing them with the board pre-heated would give you a shot at it though.
You definitely should use a stencil for VQFN or you'll just fail and get disheartened - anything at 0.5mm or finer pitch is best done properly too, even with gull-wing leads... An oven will outperform a hotplate if any components are large, as the hot plate can't heat the components directly. A hot plate can't do double sided either. I converted a cheap sandwich toaster by moving the under-side element to the top side to give more heat and more even heat.
Thanks Mark, will look at JLCPCB doing the work or a hot airgun.
That's some proper DIY with the toaster, good job. I guess you can dial it in once you get familiar with the timing.
We had an applications engineer at TI who was pretty good at hot plate soldering of 48-pin QFN/LLP packages. I think he used a combination of the hot plate and a hot air tool. Of course, the temperature is basically uncontrolled and there was some concern about that. Then one day he forgot to turn off the hot plate and absolutely cooked a board. It delaminated completely and the lab stunk of burnt PCB for a good two weeks. Our lab manager was displeased. Soon thereafter we took delivery of a $20k METCAL reflow system.
I would not use a hot plate for reflow. You'd get better control over the temperature with a toaster oven. Get the most powerful one you can find. I use a 1200 W Black & Decker one. Use a thermocouple thermometer to track the temperature. I use one by AMPROBE (= Fluke). I'm able to get reasonably close to the target temperature curve for 63/37 Sn/Pb solder by unplugging/replugging the oven at strategic times. It's pretty easy.
Adding a controller would kinda/sorta make for a "set and forget" setup. You still need to be available to open the oven door for the cool-down, though. So I'm not sure I see a huge advantage of using a controller.
And do get a solder paste stencil. OSH Stencils is your friend in need. Many of the overseas PCB outfits will also ship a stencil with the PCBs for not much extra.
Tom
I would not use a hot plate for reflow. You'd get better control over the temperature with a toaster oven. Get the most powerful one you can find. I use a 1200 W Black & Decker one. Use a thermocouple thermometer to track the temperature. I use one by AMPROBE (= Fluke). I'm able to get reasonably close to the target temperature curve for 63/37 Sn/Pb solder by unplugging/replugging the oven at strategic times. It's pretty easy.
Adding a controller would kinda/sorta make for a "set and forget" setup. You still need to be available to open the oven door for the cool-down, though. So I'm not sure I see a huge advantage of using a controller.
And do get a solder paste stencil. OSH Stencils is your friend in need. Many of the overseas PCB outfits will also ship a stencil with the PCBs for not much extra.
Tom
In the FA lab where I worked we used a hot plate all the time for soldering QFN packages. We used eval boards to test and analyze parts so we did it ALL the time. The QFN style of package exposes the package pins on the sides of the package so we pre-tinned them, in case the bottom-side didn't properly wet. Going in afterwords to address problems with a fine-tipped soldering iron would do the trick. That was done under a stereomicroscope, and we used plenty of flux because it prevented solder bridges from forming.
To prevent the solder holding other parts down from melting we used aluminum blocks strategically placed between the board and hot plate. Obviously, we place one where the DUT was going to be attached. The others were around the perimeter of the board.
One important thing to keep in mind is moisture absorption. A PCB or part that has been sitting around awhile in a relatively-high humidity environment will absorb moisture, and when heated to soldering temperature it will turn into steam and delaminate an IC package or your multilayer board. An open via won't be obvious from the outside but could play hob with your board's functionality. I know, I experienced it! So we always baked our boards and IC's @50-80C before soldering. BTW, this problem bit my company HARD, to the tune of millions of dollars, before we figured out what was going on. That's why I am preaching about it now.
Those little desiccant packages you find along with your parts in those sealed bags are there for more than just feel-good purposes.
To prevent the solder holding other parts down from melting we used aluminum blocks strategically placed between the board and hot plate. Obviously, we place one where the DUT was going to be attached. The others were around the perimeter of the board.
One important thing to keep in mind is moisture absorption. A PCB or part that has been sitting around awhile in a relatively-high humidity environment will absorb moisture, and when heated to soldering temperature it will turn into steam and delaminate an IC package or your multilayer board. An open via won't be obvious from the outside but could play hob with your board's functionality. I know, I experienced it! So we always baked our boards and IC's @50-80C before soldering. BTW, this problem bit my company HARD, to the tune of millions of dollars, before we figured out what was going on. That's why I am preaching about it now.
Those little desiccant packages you find along with your parts in those sealed bags are there for more than just feel-good purposes.