Components - In the Air Challenge

Wow, apart from the TMP112 everything listed here is in QFN or BGA package. If its really a requirement for the challenge this will be fun for everybody. Or will there be evaluation boards available (the LMP910x0 ones look interesting)?

Hi!

I think solder paste will be mandatory as one of the component purchases. Either that, or use evaluation boards. Will be interesting to see what methods people use to solder these. michaelkellett has mentioned using a hot plate to solder these. Another method I've heard is a hot air gun, but that sounds more difficult to get right without toasting the chip, but I could be wrong.

Flux would be another good thing to purchase (and tweezers, and a magnifier and very fine solder, and desoldering braid, and spare chips to experiment with) and then they may be hand-solderable with a fine tipped soldering iron (some youtube videos show a few procedures), if the pads are created with space to place the soldering iron tip right up against the edge of the ic and exposed copper on the pcb.

(There is an SMT discussion here that may help people).

Here's a picture of the processor on the board, I won't have time to do some step by step video or pictures for a couple of weeks.

The chip is a bit hidden by the test connector. You can see the sparse pinning on the two Lattice 132 pin footprints. The pads are about 0.27mm diameter.

MK

element14 have one of these.

Pre HeaterPre Heater which I'm told makes it a lot easier when you use a Hot Air reworking station and are soldering parts on.

Mark

Hi Mark,

Thanks for finding this. I've just ordered one, it's a good price It might need some sort of jig made to position the PCB over the hot spot, but I can manage that.

It's so low cost it's worth the attempt anyway, even if I can't get used to this method. I I have some thermocouples so I can measure the temperature as Michael mentioned,

and also ordered a few of the the cheapest QFN parts with a center pad too, to practice with.

Now I'm really looking forward to trying this out.

It comes with two magnetic board holders, so save the looking.

I haven't used mine, but the person I suggested it to (he got tired of waiting for a cheap chinese version), said its brilliant for desoldering parts, since you preheat from the bottom, and a bit more on top, and its off.

Yes it's a very cheap tool to add to your collection at NZ $93.

Mark

I think this preheater can be used as hot plate soldering for smd parts as it support 350C temperature... With this preheater We need solder paste and stencils for different smd footprints....

I think this preheater can be used as hot plate soldering for smd parts as it support 350C temperature... With this preheater We need solder paste and stencils for different smd footprints....

I have one of these and it's quite useful but it heats up much too fast for reliable soldering of parts using solder paste. The temperature control is very rough and ready. If you are trying to use it for re-flowing paste then initially set the temperature quite low - (check up the paste spec) to drive off the volatile stuff. Then turn the temperature up to the reflow  temperature. Using  a thermocouple to monitor temperate is a really good idea if you can. I get better results with the big iron hotplates because they heat up more slowly. If you don't drive the volatile stuff out of the paste it can end up boiling away under the chip for ages and you get voids or even unsoldered pins.

MK

I would agree that it would be too fast.

I'm wondering if a project to alter its characteristics could be worthwhile, using a Hotplate as the interface to the board.

There is a very good profile in the EnOcean specs (TCMxx from memory) which is probably a good starting point.

Regardless it's certainly a very good starting point, and is priced right.

mark

I hadn't thought about controlling the temperature - I have a salvaged temperature controller somewhere - I must dig it out.

You can buy a name brand controller from Farnell for £100 - £150, or one from ebay for £30 - I wonder if you can build one for less, ST Nucleo board, solid state relay, display, box, thermocouple and input amp - it would be very tight and a lot of effort - I'll look for the old one.

MK

MK

I was thinking about interfacing a simple temperature probe, to some form of micro and controlling the heating element.

I haven't opened up the one linked above, so I'm not sure if it has any sort of feedback loop, or the method used to interrupt the element (if at all).

Surely an SSR, Micro and Temperature Probe isn't going to add very much at all to the build, and could even be a standalone device.

I've seen some of the ovens, and while I'm not suggesting this is for large boards or BGA's, its probably suitable for a few one off situations.

Like it or not SMD is here to stay, so we better get the tools to deal with it.

Mark

It's more the time it takes to get such things going. I've found the reclaimed controller - it's a CAL9500 - can work with PTR or thermocouples. One SSR output and two relay outputs. I've often found the least cost route (including the cost of time) is to use an old PC as the controller - I have a PC controlled fridge.

MK