Okay, I need some way to get the SX52 to PCB mount. I tried to get a custom fab board through Spark Fun but they have a minum lide width of 10cm and other sites cost in the triple digits. I need an SX 52 or otherwise I will be forced to split the program into 5 SX-28s, which would be a nightmare to debug.
There is a special solder that you can buy form Digi-key [noparse][[/noparse]requires refrigeration and is shipped by courier]. You buy an adapter board, coat with this solder paste, stick the Sx-52 on the board, pop it in a cheapie toaster oven and the paste beads up and fuses to the appropriate places.
I believe I read all that at Seattle Robotics site.
Of course, don't eat toast out of that oven.
And, you are still going to pay out quite a bit for the special solder [noparse][[/noparse]$50USD] and the adapter boards. But, you might stay under $100USD dependent on how many u need.
Of course, the Proto Board at less than $10USD look mighty interesting after considering all that. [noparse][[/noparse]I bought 8.}
Min spacing for sparkfun is 8 mil, this is 0.2032 mm. The pin spacing for the SX52 is 0.65mm, this means the PQFP footprint can be used in submissions to sparkfun, it is the SX48 with it's 0.50mm spacing that cannot be used with sparkfun's fab service. Use 0.4mm wide pads spaced 0.65mm apart and this will conform to sparkfun's min spacing requirements.
There are ZIF sockets for the 52PQFP package, they are designed for programmers and cost ~$500 a peice.
Also Howard Electronics sells solder paste in small syringes, that can be shipped standard mail (without refigeration) as long as the period that it is unrefrigerated is 3 days max (send it 2nd day air) the paste will be fine, and its <$20. I have tried the paste method and was unhappy with the results, I use low temp solder and flux with a small tipped iron and it works like a charm.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔ ·1+1=10
Post Edited (Paul Baker) : 9/1/2005 4:38:30 PM GMT
Try these out, I've been using them on a regular basis for quite a while on projects around the house and at work. Just recently picked up my first set of sx supplies but I was succesful in printing and mounting for the SX/48 which is the smaller of the 2 packages using a decent cad package, ink jet printer, transparencys and photo etch boards. I·expose under a 50 watt halogen desk lamp 6" away·for 12 minutes and make sure your developer is warm, seems to help. It takes a little while to get used to but they give great results. For putting the chip down, I pre tin the pads with Kester rosin core, remove solder with solder solder wick, remove flux with alchahol. This leaves a very light "film" of solder sufficient to "tack" the sx on a few leads. The last steps are to go back, add solder using a fine tippped iron, then I apply a 50% alchahol diluted mixture of of kester acid flux and reheat with the iron. The solder flows out great leaving a nice clean well soldered chip install. Last step is to very thouroughly flush and brush the acid flux away. Usually several cleanings with alchohol. It sounds very drawn out and complicated but with a little practice you can apply a 48 package in 10 minutes or so. investment cost is minimal and for me its been a great way to come up with very clean prototypes.
The boards can be found here, price is reasonable, only part of the system that seems wasteful to me is the developer as it loses potency rather quickly once mixed.
DO NOT USE ACID FLUX! If you find it necessary to use acid flux on a circuit board, you are doing something very wrong or you have a very oxidized board. On unoxdized boards with new parts, thinned rosin flux will work fine.
To each their own Rick, I picked the method up from a local board fab house, as well as the flux. Its not necesary just very easy to work with. Maybe I was wrong in assuming that someone producing thousands of assembled boards knew what they were doing. If you have a serious thing against using a mild acid flux try this.
MFlux AR, thinned activated rosin flux complete with solvent. I think the kits are around $30 2 bottles of flux and 2 bottles of flux remover. We use them at work for applying strain gauges in wheatstone bridge circuits. Works great, ignore the acid flux listed there with it.
You are correct ChrisP that an experienced developer can use mildly acidic flux and actually get better results when doing mass production. But unless you know what you are doing, you should always stay away from acid based products when working with electronics, the potential downside is much worse than the potential upside. For a novice its best to stick with no-clean or water-clean fluxes.
Acid flux is typically used by plumbers when soldering pipes. It's NEVER, EVER used in electonics assembly. Trust me, I've been an engineer in the electronics assembly business for quite a few years. Rosin activitated flux (RA) or Rosin mildly activated flux (RMA) are sometimes used in the electronics assembly business, but the chemicals needed to remove the flux residue properly are pretty nasty to your health.
Thanks Paul, and now that this thread has totaly been hijacked from its original purpose.... I apologize to those I offended by the mention of acid based flux, still... to each their own but yes, if not carefuly, and properly used you can actually be missing traces come the next day. So I was probably very wrong in recommending the process to someone without having a very good idea of what their skill level and understanding were...Now back to our scheduled programming.
Armored Cars
Posts: 172
Comments
·· Since the SX chips do not come in a PLCC-compatible package, they will not directly plug into the socket.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com
I believe I read all that at Seattle Robotics site.
Of course, don't eat toast out of that oven.
And, you are still going to pay out quite a bit for the special solder [noparse][[/noparse]$50USD] and the adapter boards. But, you might stay under $100USD dependent on how many u need.
Of course, the Proto Board at less than $10USD look mighty interesting after considering all that. [noparse][[/noparse]I bought 8.}
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
G. Herzog in Taiwan
There are ZIF sockets for the 52PQFP package, they are designed for programmers and cost ~$500 a peice.
Also Howard Electronics sells solder paste in small syringes, that can be shipped standard mail (without refigeration) as long as the period that it is unrefrigerated is 3 days max (send it 2nd day air) the paste will be fine, and its <$20. I have tried the paste method and was unhappy with the results, I use low temp solder and flux with a small tipped iron and it works like a charm.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·1+1=10
Post Edited (Paul Baker) : 9/1/2005 4:38:30 PM GMT
The boards can be found here, price is reasonable, only part of the system that seems wasteful to me is the developer as it loses potency rather quickly once mixed.
Boards·· http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=055-108
Developer· http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=340-144
Radio shack sells the etchant.
This is VERY bad advice!
Rick
That's what I do. I found some solder flux at RadioShack and it worked great. The surface has to be pre-tinned with solder first.
Also, get a flat tip and use low heat...works well.
cbmeeks
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
http://metroidclassic.com
=========
DMCA Sucks
RIAA Sucks
http://www.vishay.com/brands/measurements_group/guide/a110/acc/so_sf.htm
MFlux AR, thinned activated rosin flux complete with solvent. I think the kits are around $30 2 bottles of flux and 2 bottles of flux remover. We use them at work for applying strain gauges in wheatstone bridge circuits. Works great, ignore the acid flux listed there with it.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·1+1=10