| chris ma |
I have tried surface mount polar caps and my experience with them was not very good. The flimsy little flaps are too fragile and broke off very easily. And they are really too small for hand soldering.
Please tell us what you experience with them. What is the best way to solder them?
Chris |
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| azira |
Are you talking like chip capacitors/resistors? Tin the pads first then place the cap/resistor/chip on the pad. Apply heat to the pad/device and when the solder heats up, the device will "sink" into the pad.
Same trick works for SMD ICs too.
--
Danny |
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| jackinnj |
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. |
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| chris ma |
| One advantage with the surface mount caps is that no holes are needed to be drilled on the pcb. |
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| Stocker |
| what sort of temperature do you use in the oven? I guess it would depend on the solder. |
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| jackinnj |
| quote: | Originally posted by Stocker
what sort of temperature do you use in the oven? I guess it would depend on the solder. |
425 F -- or so the setting says on the dial
i've only turned one board to "goo" |
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| ingvar ahlberg |
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 |
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| contaxchen |
hello,
I want to know how to tell the anode from the cathode for a surface mount eleclytic cap....:dead:
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! :dodgy:
CC |
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| chris ma |
| quote: | Originally posted by contaxchen
hello,
I want to know how to tell the anode from the cathode for a surface mount eleclytic cap....:dead:
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! :dodgy:
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 |
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| contaxchen |
HELLO,
Darkened bar? There is a darked side on the top of the caps.... But it gives postive voltage...:whazzat:
What should I do?:confused:
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 |
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| Peter Daniel |
| quote: | Originally posted by contaxchen
What should I do?:confused:
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Just connect two of them to PS. One cap with dark bar on positive, one cap with dark bar on negative. The one that explodes wasn't connected properly;) You might put them in some container to avoid any risk.
On tantalum caps dark bar means + |
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| peranders |
Why don't you look in the datasheet?
Normally the plastic foot has two cut corners = plus
some sort of stripe at the can = negative
Let me also point out that SMD parts are made for machine soldering. |
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| Stocker |
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 :bigeyes:
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 |
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| ingvar ahlberg |
| quote: | [i]
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 [/B] |
That is a tantal cap, electrolytics are always marked on negative side, some oscon types marked with + and -. |
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| Stocker |
| :dead: what a headache! at least it's possible to tell them apart. |
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| contaxchen |
hello,| quote: | | Let me also point out that SMD parts are made for machine soldering. |
yes, but for sanyo OScon, you can pull its twe legs straight and solder the cap on PCB. :cool: 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! :bawling: :bawling:
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:dead: |
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| contaxchen |
OK!!
The marked side is the cathode! This is the final conclusion after reviewing several SMD caps manufaturer's website.
C.C. |
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| jackinnj |
| quote: | Originally posted by ingvar ahlberg
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. |
Well, it might not be "right" but it works, saves a lot of time and real estate. It's much easier to remove smd parts, and it's easier to prototype. |
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| Ralphono |
| quote: | | Originally posted by ingvar ahlberg The "toaster oven" method is´nt really right for smd soldering |
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 :D .
Greetings Ralphono |
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| djQUAN |
I also use the hot air soldering equipment. comes useful for shrink tubing too. :D
I only use hot air for resistors, IC's, transistors, ceramic caps. I always think electros and tants hate high temps. |
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| gmarsh |
| quote: | Originally posted by ingvar ahlberg
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 |
so what makes a resistor "lousy" and a capacitor "rotten"?... reliability? unexplainable sonic differences?
SMD/SMT is all about :
- making products smaller - try making a handheld MP3 player using 40 pin DIPs :D
- improving the electrical performance of things. Lead inductance on a SMT IC package can be an order of magnitude better than that on an equivalent SMT package, and the lead inductance of the capacitor you decouple with it is going to be far less too. This is never a bad thing. And of course, any resistor/capacitor/transistor/etc in SMT form will have less series inductance.
- since a board made with SMT components can be made considerably smaller than one made with through-hole components, track lengths tend to be a lot shorter, radiate less EMI, pick up less ****, etc.
- Try designing a high frequency, high-performance, broadcast-quality PLL using through-hole resistors and capacitors. I dare you.
- reducing waste. When you buy SMT resistors, you don't cut the ends off them and throw them out. Much less solder is required to attach them to a board.
And reliability isn't an issue, provided that proper procedures are taken when SMT assembly is done. Mind you, SMT films and large (eg, 2512) SMT ceramics tend to thermal shock and crack way too easily during reflow. And hand-soldering can destroy a SMT capacitor in no time... so I agree with the "can't survive soldering" comment you made. |
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| djQUAN |
| quote: | | - making products smaller - try making a handheld MP3 player using 40 pin DIPs |
with SMT, I was able to make an electret mic buffer fit inside a 3" long 10mm dia aluminum tube. I don't think I could have done that with throughhole components. and the SQ is still good. very quiet too. |
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| peranders |
| quote: | Originally posted by chris ma
I have tried surface mount polar caps and my experience with them was not very good. The flimsy little flaps are too fragile and broke off very easily. And they are really too small for hand soldering.
Please tell us what you experience with them. What is the best way to solder them? |
They are pretty easy to solder by hand.
1 Wet the cap's connections with fresh tin.
2 Put fresh tin on one pad.
3 Warm this pad and slide the capacitor into it's place.
4 Warm the other pad and maybe add some more tin and burn good for a while because you have a very little connection which can be reached by the soldering iron.
Pretty easy! |
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| gmarsh |
| quote: | Originally posted by djQUAN
with SMT, I was able to make an electret mic buffer fit inside a 3" long 10mm dia aluminum tube. I don't think I could have done that with throughhole components. and the SQ is still good. very quiet too. |
Since we're talking small... attached is one of the latest things I've designed - a 60W complimentary feedback BJT amplifier, built primarily using 0603 SMT parts on a 1.5" by 3.25" PCB. |
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| peranders |
Looks very good! :nod: Care for to show us more? (in case of yes, please start a new thread)
I'm also into surface mounted as you may have noticed. I persnally realy like it but mostly for it's coolness, maybe also for it's good properties.... them somebody amy ask: how does it sound compared to holemounted parts? I don't know.... because I don't. The only thing I know is that I like it. |
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| djQUAN |
| quote: | Originally posted by gmarsh
Since we're talking small... attached is one of the latest things I've designed - a 60W complimentary feedback BJT amplifier, built primarily using 0603 SMT parts on a 1.5" by 3.25" PCB. |
I assume the output stage is not yet installed? if it's onboard, how do you heatsink it? |
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| peranders |
| Every part has impact on the sound but the question is how much. Jam, have you tested many different SMT parts? |
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| jackinnj |
| quote: | Originally posted by gmarsh
- Try designing a high frequency, high-performance, broadcast-quality PLL using through-hole resistors and capacitors. I dare you. |
working with high speed current-feedback opamps is more of a problem in through-hole versus surface mount --
i would like to see someone compare the film and phenylene sulfide SMT capacitors with their through-hole counterparts. |
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| Peter Daniel |
I was recently experimenting with PLL filter in CS8412 and through hole parts sounded actually better than regular SMD resistors and capacitors.
Any links to those film and phenylene sulfide SMT capacitors, as I would be indeed interested in trying something better. |
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| peranders |
| quote: | Originally posted by jackinnj
i would like to see someone compare the film and phenylene sulfide SMT capacitors with their through-hole counterparts. |
From what I know these are only available as SMT. |
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| peranders |
| quote: | Originally posted by Peter Daniel
I was recently experimenting with PLL filter in CS8412 and through hole parts sounded actually better than regular SMD resistors and capacitors.
Any links to those film and phenylene sulfide SMT capacitors, as I would be indeed interested in trying something better. |
Peter, how many do you want? You can get a couple from me. |
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| Peter Daniel |
| If you have 0.22 and 0.47u I would be interested in 2pcs each, just to try. Also, 3n3 would come handy. |
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| peranders |
| You can have 4 pcs. 100 nF. This is the only value I have. |
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| Peter Daniel |
| Those would be fine too. I can always put them in parallel. |
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| gmarsh |
| quote: | Originally posted by peranders
Looks very good! :nod: Care for to show us more? (in case of yes, please start a new thread)
I'm also into surface mounted as you may have noticed. I persnally realy like it but mostly for it's coolness, maybe also for it's good properties.... them somebody amy ask: how does it sound compared to holemounted parts? I don't know.... because I don't. The only thing I know is that I like it. |
I could make a thread about it... The amp is more or less stolen from Randy Slone's amp design book (it's a 11.4 with a few component changes, more or less) so I'm not sure if there's any copyright issues involved in posting it. Convince me to make a thread, and I will.
Here's my impressions on this amp:
I built an "original" slone 11.4 using his parts (2N5401/5551 small signal 2SB649/2SD699 VAS/predriver/bias, 1302/3281 output) and ran into stability problems. I reduced the amp's open loop gain to stabilize it, and it was fine. Sounded great.
This amp uses MMBT5x01, MJE340/350 and MJW21193/4 transistors, and all-original-11.4 component values with the exception of a different DC coupling cap on the input. After building it and powering it up, NO STABILITY PROBLEMS! Didn't have to change a single part.
But the SMT amp sounds... great, too. My ears can't tell a difference.
| quote: | Originally posted by djQUAN
I assume the output stage is not yet installed? if it's onboard, how do you heatsink it? |
See attachment. And don't laugh at my output board (done in a rush, and I got IN/OUT backwards) |
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| Peter Daniel |
| Interesting use of nuts istead of standoffs. ;) |
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| Swedish Chef |
gmarsh,
that amp looks really nice! One thing I have against any large SMD components is their mechanical strength to the PCB. At one company I used to work for we finally gave up on large SMD caps for their handheld products. They simply fell off the board all the time after a unit was dropped. SMD connectors can be a PITA too. ;)
| quote: | | I was recently experimenting with PLL filter in CS8412 and through hole parts sounded actually better than regular SMD resistors and capacitors. |
Yeah, I'm pretty sure the SMD components themselves are the one to blame. Can't have anything to do with simple loop dynamics, naah... :rolleyes: |
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| peranders |
| quote: | Originally posted by Swedish Chef
One thing I have against any large SMD components is their mechanical strength to the PCB. |
Your totally right about that. You must pay attention to if the pcb will be bent especially. Long time ago I used to use resistor nets (SIL's) and the were very sensitive against bending pcb. They cracked :( |
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| gmarsh |
| quote: | Originally posted by Peter Daniel
Interesting use of nuts istead of standoffs. ;) |
hey now, it's the prototype - gimme a break.
The final version of the amp will have a case which will hide the nuts and screws that hold the PCBs in place. ;) |
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| jackinnj |
| quote: | Originally posted by Peter Daniel
Interesting use of nuts istead of standoffs. ;) |
btw, there are a lot of sellers of standoffs on the Bay -- for a couple bucks you can get hundreds. (who needs hundreds?) |
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| Peter Daniel |
Actually I was admiring the creativity ;)
Nothing wrong with mounting boards in this way. |
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| gmarsh |
| quote: | Originally posted by Peter Daniel
Actually I was admiring the creativity ;)
Nothing wrong with mounting boards in this way. |
It works, and it's very secure.
I do have standoffs, but there's a couple of problems...
- my standoffs are threaded
- a couple of the heatsink holes are drilled into fins, so I can only put a screw in from the amplifier side.
So if I put a screw in, I can either tighten the standoff against the amplifier PCB, or tighten it against the heatsink. Doing either will prevent the screw from turning so I can't tighten everything together all at once.
Using two nuts instead of a standoff means I can keep everything tight. And to the person that said I can get cheap standoffs really easily, I'd like to see you find an 8mm standoff that's as cheap as two M3 nuts. :D |
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| Sigurd Ruschkow |
A nice SMD soldering method is to use a hot plate. Weller sells one and you can set the temperature of the hot plate to what the solder paste requires.
First, put solder paste onto the pads, and then put the SMD components on the paste, and then put the PCB on the plate.
As the PCB gets hot the solder will melt and the components will nicely be "sucked" to the center of the pad.
Just watch out for bent PCBs when heating them. One can put some heavy parts on the edges of the PCB so it stays flat.
Sigurd |
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| Sigurd Ruschkow |
I find it hard to agree that SMD resistors are all bad. There are some very good SMD resistors out there. It is just hard to find them (and sometimes to buy them). They can be very expensive resistors but that is also the case with hole mounted audiophile resistors like Vishay S102k and Caddock MK132 and Riken resistors.
I am thinking about Vishay's SMD bulk foil resistors.
Here are some links to the VSMP resistors:
http://www.vishay.com/docs/63096/vsmp1206.pdf[/URL]
http://www.vishay.com/docs/63099/vsmp1506.pdf[/URL]
You can also see on this photo that even Mark Levinson is using SMD resistors for their attenuator board:
http://www.marklevinson.com/image_library/32AB_lo.jpg
That preamp sounds rather good according to the people who have reviewed it.
Sigurd
| quote: | Originally posted by ingvar ahlberg
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.
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| jackinnj |
| quote: | Originally posted by gmarsh
Using two nuts instead of a standoff means I can keep everything tight. And to the person that said I can get cheap standoffs really easily, I'd like to see you find an 8mm standoff that's as cheap as two M3 nuts. :D |
...and a lock-washer |
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