Author Topic: Show us your SMD stuff.  (Read 30603 times)

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wavley

Re: Show us your SMD stuff.
« Reply #60 on: October 02, 2015, 01:33:45 PM »
^

I am surprised conductive epoxy would provide a good enough contact with low enough resistance to be usable for an RF amplifier.  It certainly does overcome the problems of excessive soldering heat.

It's actually quite great stuff =84]http://www.epotek.com/site/component/products/productdetail.html?cid[0]=84

It's really the only reliable way to assemble cryogenic chip and wire or MMIC components, a lot of components we use are only about 10 mils (the thousandth on an inch mil) square.  Because of it's relatively low frequency (we consider anything with a coax input low frequency, above that is waveguide) I could get away with a PCB design, but usually we glue components straight down to a gold plated chassis or CuFlon substrate with epoxy and wire bond the components.  I've built amps up to 120 GHz, above that the SIS Mixer guys come in.  Recently I've mostly been prototyping either low frequency (1-2 GHz) Phased Array Feed stuff, new ways of phase stable local oscillator distribution, some photonics stuff, and some 60-90 GHz amps.  When I first started 8 years ago I was just in low noise amp production for the VLA in New Mexico, but now I'm really enjoying R&D.  You'd be surprised how much my audio experience comes into play.

A lot of information about my lab is here: https://science.nrao.edu/facilities/cdl
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Cozybuilder

Re: Show us your SMD stuff.
« Reply #61 on: October 02, 2015, 02:16:02 PM »
Just wondering if this conductive epoxy will work as well with copper PCBs? It might open up a whole new way of building for those of us still in through-hole land.
Some people drink from the fountain of knowledge, others just gargle.

wavley

Re: Show us your SMD stuff.
« Reply #62 on: October 02, 2015, 03:30:59 PM »
Just wondering if this conductive epoxy will work as well with copper PCBs? It might open up a whole new way of building for those of us still in through-hole land.

The stuff is great and easy to work with once you get used to dabbing it on with a pin vice (I have needles bent, flattened, and sharpened all sorts of ways to get down into RF channels, but for regular PCB work a sewing needle or syringe would be just fine, you can even stencil it on for big operations)  I find it's a lot easier to epoxy some things because you can put the put the epoxy on the pad and drop the components in with tweezers and make sure it's settled in.  For me it's better than tweezers in one hand, soldering iron in the other.

Keep in mind, there is no cleaning action of the flux so whatever you're working on needs to be very clean, the Enepig board in the picture doesn't oxidize and takes solder, epoxy, gold wire, and aluminum wire equally as well which makes it great to work on.  When I use it on a copper board I make sure it's nice and shiny, then I keep a ceramic IC next to my microscope and I scrub all the tinned components on it before I place them, gold plated stuff is fine the way it is.

The other part to remember is that it shears pretty easy, if you have a nice stable substrate it will cool down to 15 Kelvin hundreds of times, no problem, but if you are going to flex or bend it at all it will break which is why my power connector is soldered and then glued with non-conductive epoxy.

And lastly, you need an oven or hot plate to cure it properly, otherwise you will have to wait a week for it to cure at room temperature, generally I do 20 minutes at 120C.   
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Cozybuilder

Re: Show us your SMD stuff.
« Reply #63 on: October 02, 2015, 05:07:54 PM »
Thank you,very informative  ;D

I think this is something worth pursuing.
Some people drink from the fountain of knowledge, others just gargle.

alexanderbrevig

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Re: Show us your SMD stuff.
« Reply #64 on: October 20, 2015, 08:24:57 AM »
Not a guitar pedal, but it's definitely SMT:


Several 0402 parts, I'll think twice before using that for hand assembly again.

pickdropper

Re: Show us your SMD stuff.
« Reply #65 on: October 25, 2015, 08:28:50 PM »
Very nicely soldered.

I'm surprised you found the 0402 resistors more difficult than the higher pin count chips.

0402s are fairly easy to get used to.  0201s on the other hand are really really small.  I haven't tried 01005s yet.

Ice-9

Re: Show us your SMD stuff.
« Reply #66 on: October 31, 2015, 06:13:22 PM »
Not a guitar pedal, but it's definitely SMT:


Several 0402 parts, I'll think twice before using that for hand assembly again.

Great job on the hand soldering, I agree that I find it easier to solder the IC's over the ting resistors. Tack one corner then the opposite and the rest of the pins are easy.

Next time I get a PCB made with that much SMD though I think it worth while getting a solder paste stencil included. 

Nice job. :)
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pickdropper

Re: Show us your SMD stuff.
« Reply #67 on: October 31, 2015, 10:18:00 PM »

Next time I get a PCB made with that much SMD though I think it worth while getting a solder paste stencil included. 


I think I'm weird.  I actually find it more difficult to apply solder paste evenly (with or without a stencil) than to solder by hand.  Reflowing does save a good chunk of time, however.

Obviously, if there are BGAs or QFNs or components with thermal pads, then hand soldering isn't an option.

duck_arse

Re: Show us your SMD stuff.
« Reply #68 on: November 11, 2015, 08:59:59 AM »
ONLY for rough-hacking, slash-and-burn clots like me, or if you get depressed by winter:

shown is not really an smd build, but for build helping. it's my new heat-soaker, boasting a MASSIVE 1.2 WATTS OF PURE ... erm .... warmth. it consists of a 7805 reg and 47R load resistor (shoulda used that 10R) mounted under an intel-style pentium heatsink, all clamped up in a lump of wood.




turn it over and you see how it [is intended to] works. double sided tape yr board to the black, tastefully arrange yr parts about the place, place another heatsink on top and do something else for 20 minutes. when you come back, the parts and board have some preheat/soak to them, so you spend less iron-time soldering them.



it even has some bishops graphics taping-tape around the edges to stop runaways. it does work/warm, but is yet to be used in anger. it could have temp-sense/comparator/mosfet controller added (greaser_au - different, but same principle), but switching it off if it gets too hot will work as well.

[edit :] oops.
« Last Edit: November 11, 2015, 10:56:41 AM by duck_arse »
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alanp

Re: Show us your SMD stuff.
« Reply #69 on: February 18, 2017, 10:21:46 PM »


Mutable Instruments Elements. Another great Olivier Gilette design!

The biggest issue I had was getting the firmware to upload, until I realised that the TX and RX wires were crossed.