koolkid731 said:
Paste can be a pain to dispense but if you can solder all the parts properly in one pass it's worth the effort. Normally parts stay in place fairly well unless you really whack the board or drop it. The tiny size and mass of SMDs means low inertia. You'd be amazed at how fast a pick and place machine operates at full speed and it just places the parts onto pads covered in solder paste without them falling off.
Some fluxes (and solders with flux cores) are designated as no clean, so you don't need to clean them off the PCB. Others can be toxic and even conductive if left on the board. Generally it just looks nicer if you clean the board off too. Here are a couple good articles to check out:
http://www.circuitnet.com/experts/EQ10123.shtml
http://www.logwell.com/tech/servtips/cleaning.html
As it says in the one article, cleaning flux with alcohol and brush is pretty worthless unless you remove the residue from the PCB. Lint free wipes such as Kimwipes are great for this purpose. Or you can find a good lint free resuable towel.
If you get really keen you can etch your own paste stencil in 0.005" brass sheet. I did this when I had a bunch of the same board to make. Its actually very easy.
Reflow can be done in a cheap toaster oven - just stick in a thermocouple, and run up from cold to about 205C then turn off and allow to cool slowly. My workmate successfully soldered a small BGA device on a homebrew pcb using this technique.
The nice thing about reflow is you don't have to be too precise with component placement - the surface tension of the molten solder pulls everything nicely into alignment.
Reflow can be done in a cheap toaster oven - just stick in a thermocouple, and run up from cold to about 205C then turn off and allow to cool slowly. My workmate successfully soldered a small BGA device on a homebrew pcb using this technique.
The nice thing about reflow is you don't have to be too precise with component placement - the surface tension of the molten solder pulls everything nicely into alignment.
Circuit Cellar had a toaster oven controller about 5 years ago -- this was surpassed by an article in Elektor with an oven controller which mimic-d the actual heating and cooling profile of the expensive reflow ovens. i just use a toaster oven purchased at a local bed and bath store and find it works well.TwoSpoons said:
if you get your workspace and work-chair at the right level you can hand solder SOIC's and 0603's by tacking one end down -- i use a very, very fine pair of tweezers from Italy.
I am quite an avid follower of goings on on the head-fi forum....
I have seen many people remark how much better their smd projects ended up sounding compared to the same item in leaded format... I think the headphone setups are ideal for hearing subtle diffirences like that.
I have yet to bite the bullet and buy enough SMD components to actualy build anything, but I do intend to move to SMD just for extending the lifetime of my hobby... I think at some point leaded will be very scarce...
I have seen many people remark how much better their smd projects ended up sounding compared to the same item in leaded format... I think the headphone setups are ideal for hearing subtle diffirences like that.
I have yet to bite the bullet and buy enough SMD components to actualy build anything, but I do intend to move to SMD just for extending the lifetime of my hobby... I think at some point leaded will be very scarce...
Nordeek -- i like smt 'cause i don't like drilling holes -- my surface mount super regulator works as well as the through-hole version (I did buy the Old Colony boards to compare the two devices) and the SMT version is about 1/2 the size so it's great for retrofits. If you are going to burn your own boards it is very simple to do so with these components.
SMT components are cheaper -- you can buy assortments of parts from folks like Jameco, Digikey, Mouser and the tolerances are also better.
of course you won't find polystyrene caps -- these would turn into goo in an a reflow oven.
SMT components are cheaper -- you can buy assortments of parts from folks like Jameco, Digikey, Mouser and the tolerances are also better.
of course you won't find polystyrene caps -- these would turn into goo in an a reflow oven.
I now do lots of SMD soldering. I use solder paste and a toaster oven converted into a reflow oven. For prototyping, I apply the solder paste with a syringe and a fine tip. For production, I use a stencil and squeegee (from Stencils Unlimited).
I was apprehensive at first, but now that I have been doing it for a while, I definitely prefer SMD to through hole. For building, it is much faster. For repair, I use hot tweezers. Repairing through hole is not any easier. With hot tweezers, you just grab the smd part and lift it off. You can use them to put the new part on as well, then touch up the joints.
I do all my part placement by hand with tweezers. For ICs I sometimes use a $7 vacuum pickup pen, then nudge the part with the tweezers. I have a hot air station but haven;t used it for anything in a long time.
I am a bit mystified about availability comments. I find it is getting harder to find good through hole parts (apart from MKP and MKT caps). Take a look at Susumu thin film resistors at DigiKey. I am switching over to their RR series for almost all of our stuff (0805). We will be using 0.1% parts everywhere because they are so inexpensive.
Vishay has some nice 1% 2W power resistors too. Between C0G ceramics and Panasonic PPS films, I can get just about anything I need. Panasonic FK SMD el caps are the same as their FM through hole series.
Transistors and IC packages are generally identical parts, just a smaller package. There are cases where you run into thermal issues with the smaller packages, but that is changing. Look at Zetex and others, the power ratings are creeping up. If it's really an issue, just add a through hole part where you need it, and do smd for the rest.
I was apprehensive at first, but now that I have been doing it for a while, I definitely prefer SMD to through hole. For building, it is much faster. For repair, I use hot tweezers. Repairing through hole is not any easier. With hot tweezers, you just grab the smd part and lift it off. You can use them to put the new part on as well, then touch up the joints.
I do all my part placement by hand with tweezers. For ICs I sometimes use a $7 vacuum pickup pen, then nudge the part with the tweezers. I have a hot air station but haven;t used it for anything in a long time.
I am a bit mystified about availability comments. I find it is getting harder to find good through hole parts (apart from MKP and MKT caps). Take a look at Susumu thin film resistors at DigiKey. I am switching over to their RR series for almost all of our stuff (0805). We will be using 0.1% parts everywhere because they are so inexpensive.
Vishay has some nice 1% 2W power resistors too. Between C0G ceramics and Panasonic PPS films, I can get just about anything I need. Panasonic FK SMD el caps are the same as their FM through hole series.
Transistors and IC packages are generally identical parts, just a smaller package. There are cases where you run into thermal issues with the smaller packages, but that is changing. Look at Zetex and others, the power ratings are creeping up. If it's really an issue, just add a through hole part where you need it, and do smd for the rest.
I've used my "dedicated" toaster oven for MSSOP parts, haven't done any BGA but I am game to try this.
The WIMA SMD parts aren't yet available at Mouser, but I will call their US Distributor after the New Year and see where we can get some. They've been helpful to me in the past (anyone who needs the Wima MK2S-XL 10u/16V let me know by PM).
The WIMA SMD parts aren't yet available at Mouser, but I will call their US Distributor after the New Year and see where we can get some. They've been helpful to me in the past (anyone who needs the Wima MK2S-XL 10u/16V let me know by PM).
Here is where I got the oven controller: http://www.thesiliconhorizon.com/reflow.htm
Here are the hot tweezers I use (incredibly good deal as well). I use the tweezers attached to my hot air station but same thing):
http://store.sra-solder.com/product.php?xProd=6370&xSec=22
SRA has good deals on solder paste as well, though I got mine from Stencils Unlimited:
http://store.sra-solder.com/section.php?xSec=15
http://www.stencilsunlimited.com/solder-paste.php?osCsid=1a0d004f1c650684e24a55eba1284ae8
I have been using the same syringe of paste for about 6 months now. I left if out in a warm room a few times and it started to separate, so I pulled the plunger out, stuck a tiny screw driver in and mixed it up. Been fine ever since. My New England basement workshop is generally cool enough these days to just leave it on the workbench.
Here are the hot tweezers I use (incredibly good deal as well). I use the tweezers attached to my hot air station but same thing):
http://store.sra-solder.com/product.php?xProd=6370&xSec=22
SRA has good deals on solder paste as well, though I got mine from Stencils Unlimited:
http://store.sra-solder.com/section.php?xSec=15
http://www.stencilsunlimited.com/solder-paste.php?osCsid=1a0d004f1c650684e24a55eba1284ae8
I have been using the same syringe of paste for about 6 months now. I left if out in a warm room a few times and it started to separate, so I pulled the plunger out, stuck a tiny screw driver in and mixed it up. Been fine ever since. My New England basement workshop is generally cool enough these days to just leave it on the workbench.
Mirand A1 i have made.
I Wonder what did go wrong with my design.
I believe that people was frightend by the number fo SMT parts on the board.
Even Hugh from AKSA said that the price was nearly to fair!
The swedish hififorum.nu did some comparison to valveamplifiers. And they where satisfied with it:
"Enligt mina öron lät det
Rytmniskt steg som levererat ett djup och en potent botten. Dessutom skall man komma ihåg att steget inte är inspelat än "
"Den spelade RIKTIGT bra!!! Skall se om jag kan få lite mer INTRYCK.
Det som jag kommer på nu är att den spelar djupt. HELA (?) basregistret är med."
Just to mention a two of the responses. So i was i bit pussled about only selling 10 units.
I will maybe start up making a second attempt as i have a SMT machine and oven. And then i will only produce them as preassembled board, then people can concentrate on making stunning enclousure instead...
The enclousure is the sign of a person DIY work.
So if it dies out again.... Then burn buren!!!
I Wonder what did go wrong with my design.
I believe that people was frightend by the number fo SMT parts on the board.
Even Hugh from AKSA said that the price was nearly to fair!
The swedish hififorum.nu did some comparison to valveamplifiers. And they where satisfied with it:
"Enligt mina öron lät det
Rytmniskt steg som levererat ett djup och en potent botten. Dessutom skall man komma ihåg att steget inte är inspelat än "
"Den spelade RIKTIGT bra!!! Skall se om jag kan få lite mer INTRYCK.
Det som jag kommer på nu är att den spelar djupt. HELA (?) basregistret är med."
Just to mention a two of the responses. So i was i bit pussled about only selling 10 units.
I will maybe start up making a second attempt as i have a SMT machine and oven. And then i will only produce them as preassembled board, then people can concentrate on making stunning enclousure instead...
The enclousure is the sign of a person DIY work.
So if it dies out again.... Then burn buren!!!
Once you get used to SMD it is all you will want to use. I use an OKi MFR series station with tweezers and it makes SMD a breeze. I am much faster both soldering and desoldering SMD components (0603 through big QFP packages) than I am with through-hole stuff.
The only exception to this is SMD devices with thermal pads meant to be attached to the board. Those are a serious pain unless you have a hot air machine / reflow oven / etc. And even then they can be very difficult.
The only exception to this is SMD devices with thermal pads meant to be attached to the board. Those are a serious pain unless you have a hot air machine / reflow oven / etc. And even then they can be very difficult.
SMD FTW!! indeed once you are used to working with SMD, you really find it difficult to justify using anything else. I need to build myself an oven with controller, love the links in here. tghinking i'll get that infraoven and then build a controller with it.
of course some devices are simply not available, but that list is becoming smaller and smaller, with Si fets available, zfoil resistors available (within a limited range of values) and pretty nice film caps too, really dont get this whole thing on here and other forums where people will simply replace or remove anything SMD, often without even knowing what its for; hell sometimes in spite of knowing what its for!! like a particular brand of fool that replaces ceramic decoupling caps in a clock circuit and replaces it with massive inductive airsculptures made of old nos oil caps or of course blackgates, you know that blackgate is great at everything, fantastic in the Mhz range too....
funniest thing ive seen I think was someone unknowingly replacing SMD oscons with leaded ones and using wima metalized film somewhere where an SMD PPS or pet would have fit quite easily. its too funny
of course some devices are simply not available, but that list is becoming smaller and smaller, with Si fets available, zfoil resistors available (within a limited range of values) and pretty nice film caps too, really dont get this whole thing on here and other forums where people will simply replace or remove anything SMD, often without even knowing what its for; hell sometimes in spite of knowing what its for!! like a particular brand of fool that replaces ceramic decoupling caps in a clock circuit and replaces it with massive inductive airsculptures made of old nos oil caps or of course blackgates, you know that blackgate is great at everything, fantastic in the Mhz range too....
funniest thing ive seen I think was someone unknowingly replacing SMD oscons with leaded ones and using wima metalized film somewhere where an SMD PPS or pet would have fit quite easily. its too funny
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