i do the toaster oven method -- now probably on my 20th project -- I use a ultrafine tweezer to apply the solder paste -- I have a loupe which, when reversed, magnifies beautifully -- then carefully place the resistors, caps and IC's onto the pads -- of course it helps if you don't drink a lot of coffee.
they take about 2 1/2 to 3 minutes in my special purpose toaster oven - the board will start to fry if you go any longer. obviously, since there are lead fumes involved you don't want to use the toaster oven for any purpose dealing with food.
quite frankly, smt's make it a lot easier to work and the precision of the parts is excellent -- typical matching of resistors on the same reel is usually around 0.1% to 0.5% for resistors -- as if you are making your own filters or differential amplifiers -- are a boon. further, smt opamps, voltage regulators, gate-drivers even the high quality items, seem to be much less expensive and more plentiful on EBay.
they take about 2 1/2 to 3 minutes in my special purpose toaster oven - the board will start to fry if you go any longer. obviously, since there are lead fumes involved you don't want to use the toaster oven for any purpose dealing with food.
quite frankly, smt's make it a lot easier to work and the precision of the parts is excellent -- typical matching of resistors on the same reel is usually around 0.1% to 0.5% for resistors -- as if you are making your own filters or differential amplifiers -- are a boon. further, smt opamps, voltage regulators, gate-drivers even the high quality items, seem to be much less expensive and more plentiful on EBay.
The "toaster oven" method is´nt really right for smd soldering, for reflow soldering You need an extremely tight control of heat curve: preheating to activate flux in paste- reflow- rapid cooling.
Precision in chipresistors is good but it is still lousy resistors, You can find metalfilm resistors in melfpackages but nothing close to the quality of even the most comon through hole metal film resitors. SMD/SMT is all about producing high volume cheaply.
SMD semiconductors are as good as throug hole types, but filmcapacitors, for instance, are rotten and seldom survive soldering. Drill holes, if You´re not into making cellular phones
Precision in chipresistors is good but it is still lousy resistors, You can find metalfilm resistors in melfpackages but nothing close to the quality of even the most comon through hole metal film resitors. SMD/SMT is all about producing high volume cheaply.
SMD semiconductors are as good as throug hole types, but filmcapacitors, for instance, are rotten and seldom survive soldering. Drill holes, if You´re not into making cellular phones
hello,
I want to know how to tell the anode from the cathode for a surface mount eleclytic cap....
I just recieves a bunch of surface mount sanyo os con. I don't understand the marking on them. It's my first time to use them.
If i use my DMM to test its voltage for both ends, I probably can see which one is the cathode. In case that the caps are too old, this method could be indeterministic. Just give me a hint!
CC
I want to know how to tell the anode from the cathode for a surface mount eleclytic cap....
I just recieves a bunch of surface mount sanyo os con. I don't understand the marking on them. It's my first time to use them.
If i use my DMM to test its voltage for both ends, I probably can see which one is the cathode. In case that the caps are too old, this method could be indeterministic. Just give me a hint!
CC
contaxchen said:hello,
I want to know how to tell the anode from the cathode for a surface mount eleclytic cap....
I just recieves a bunch of surface mount sanyo os con. I don't understand the marking on them. It's my first time to use them.
If i use my DMM to test its voltage for both ends, I probably can see which one is the cathode. In case that the caps are too old, this method could be indeterministic. Just give me a hint!
CC
There should be a marking of a darkened BAR on the top of the cap to indicate the negative side of the leg at the bottom.
Hope this help.
Chris
HELLO,
Darkened bar? There is a darked side on the top of the caps.... But it gives postive voltage...
What should I do?
I think the SMD caps follow the same tradition as conventional ones, but... most of my caps' darked side shows they are anode...
I will just follow what you said.
Thanks
lhchen
Darkened bar? There is a darked side on the top of the caps.... But it gives postive voltage...
What should I do?
I think the SMD caps follow the same tradition as conventional ones, but... most of my caps' darked side shows they are anode...
I will just follow what you said.
Thanks
lhchen
Speaking of drilling holes unless it's for cell phones... I just read an article in a trade magazine discussing relative merits of bonding wire to terminals on the ICs that are stacked FOUR and FIVE tall inside cell phones 
anyhow- On some of our PCBs here at work, the surface mount caps have a stripe on one side that is oriented toward a "+" printed on the PCB.
HTH
anyhow- On some of our PCBs here at work, the surface mount caps have a stripe on one side that is oriented toward a "+" printed on the PCB.
HTH
hello,
Their quality seems better than the ones with soldering lugs. I am surprised by it superb metal finish. Nice sense of touching.
It's useless to tear them apart.... I have checked out the structure diagram. The anode is almost symmetric to its cathode. really!
Also, I don't think it gonna blow up if you reverse the positive and it negative. At most, the wrong positioning shorten the cpas life.
That's it.
CC
yes, but for sanyo OScon, you can pull its twe legs straight and solder the cap on PCB.
Their quality seems better than the ones with soldering lugs. I am surprised by it superb metal finish. Nice sense of touching.It's useless to tear them apart.... I have checked out the structure diagram. The anode is almost symmetric to its cathode. really!
Also, I don't think it gonna blow up if you reverse the positive and it negative. At most, the wrong positioning shorten the cpas life.
That's it.
CC
For SMD rework at work we use a hot-air heat gun at about 400°C with special flux. This method makes out beautiful shiny melted tin. Just place the parts into the paste and look the melting tin. Remove the hot air if the tin is melten completely. You can solder part by part with this method.
You can also solder SMD parts per hand - 0,2mm pitch is possible - although i got an hurting red eye after 500 pins
.Greetings Ralphono
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.