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Old 19th August 2002, 08:24 PM   #1
jwb is offline jwb  United States
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Default Surface mount components poorly regarded

I have noticed, since joining this forum a few months ago, that certain people profess a very negative opinion of surface-mount parts. I wonder why this is. These people seem to think that SMD parts are to be looked down upon as inferior to leaded parts. I find this extremely weird.

Take the case of SMD resistors. Several people on this board have recommended against SMD resistors. I have never seen an actual reason given. I think this is bogus, because SMD resistors have all the apparent advantages:
  • Manufactured on advanced processes
  • Small
  • Low noise
  • Low inductance
  • Great temperature coefficient of resistance

I frankly don't see what resistors with axial leads have going for them. The newest SMD resistors are better in every way, except for power handling. But I think SMD is definitely the right choice for attenuators, terminators, filters, current sources, and low-power circuitry of all kinds.
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Old 19th August 2002, 11:37 PM   #2
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It makes sense to me. But the forum's motto is "by the fanatics, for the fanatics". What do you expect?

They probably don't like them because they are the wrong color...

MR
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Old 20th August 2002, 12:05 AM   #3
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Default Wait until you step on an AD797

You don't know you've even dropped an SMT device, at least with through-hole you can attempt to straighten out the pins. I just ordered a batch of SMT devices this afternoon.

I use both. SMT can help keep your sanity since you don't have to drill gazillion holes on 0.100 centers.
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Old 20th August 2002, 03:50 AM   #4
tiroth is offline tiroth  United States
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Default Re: Wait until you step on an AD797

Quote:
Originally posted by jackinnj
I use both. SMT can help keep your sanity since you don't have to drill gazillion holes on 0.100 centers.
Amen.
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Old 20th August 2002, 05:24 AM   #5
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Default Re: Surface mount components poorly regarded

Quote:
[i] Several people on this board have recommended against SMD resistors. I have never seen an actual reason given. I think this is bogus, because SMD resistors have all the apparent advantages:
  • Manufactured on advanced processes
  • Small
  • Low noise
  • Low inductance
  • Great temperature coefficient of resistance

I frankly don't see what resistors with axial leads have going for them. The newest SMD resistors are better in every way, except for power handling. But I think SMD is definitely the right choice for attenuators, terminators, filters, current sources, and low-power circuitry of all kinds. [/B]
It all is true except for one thing: how do they sound? Quite a few people here pay at least $4 for a single resistor, because being fanatics they don't accept anything that might degrade the signal path in the equipment they build. And you are trying to tell them that SMD resistors have advantage?

Personally I never even bothered to check them out (SMD), maybe I should though? Then, I wouldn't be able to built circuits like this. (Aleph P1.7).
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Old 20th August 2002, 06:30 AM   #6
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Default Re: Surface mount components poorly regarded

[
Take the case of SMD resistors. Several people on this board have recommended against SMD resistors. I have never seen an actual reason given. I think this is bogus, because SMD resistors have all the apparent advantages:
  • Manufactured on advanced processes
  • Small
  • Low noise
  • Low inductance
  • Great temperature coefficient of resistance

----------------------------------------------------------------
Most SMD resistors are magnetic. They do not have lower noise and TC and they are very difficult to store/find as components. Advanced manufacturing processes can mean higher profits only.

SMD capacitors have poorer dielectrics than audiophile pp or ps ones. They are excellent for decoupling.
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Old 20th August 2002, 07:27 AM   #7
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I don't have an answer to quality of smd's (resistors or capacitors), but as a DIY or repair center you're confronted with:

1. little things that are harder to solder
2. measuring on smd's is harder (without making bad contacts or even destructive smoking signals)
3. availability is poor
4. bad solderings poorly tracable
5. value readings poor to non available
6. if you found the bad smd unsoldering is harder and require hot air devices with special mouth for each different size IC.

This is typical for our society: ? don't work? trow away and buy new! It's cheaper....
This is NOT compatible with my DIY point of view.

Imaging making test-pcb's with 40 % or more non-recyclable material.

Worked for Siemens during my vacation some 20 years ago when smd made it's first steps. Haha, walking between the ultra-sonic bath to remove soldering flux and test-bank and soldering-iron.
Good soldering-pasta and mask-allignement were problems at those days, guess that improved, but repair is hard, very hard.
In many cases you HAVE TO take whatever they charge you for a new board, you lose a lot of 'independence' that way.

In many ways I more like a Harley with poorer reliability, but I can fix it myself, instead of that flashy jap made of a few thousand non-refurbishable parts.
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Old 20th August 2002, 07:38 AM   #8
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oh yeah, forget replacing that cap with black-gates or try not to find out that a dale or other resistor sounds better, you've got no space or better, no choice.
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Old 20th August 2002, 08:01 AM   #9
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For SMD caps, the situation is easy. Most SMD caps are ceramic, if film caps are available, they are Mylar (polyester). I haven't come across a polypropylene or polystyrene SMD cap yet.

For resistors, one things is obvious: due to their smaller size, there can be more thermal distortion, but I'd only worry about this for applications where the peak load is a seizable percentage of rated wattage, i.e. feedback resistor in power amp.

The other point is the resistive film. It used to be true that if you bought 1% parts, they were automatically metal film (aka thin film). I'd say that those are pretty much beyond doubt.

Now thick film SMD parts are becoming available with tolerances of 1 and even 0.5%. Problem is, they usually don't tell you what the thick film is. I suppose it could be carbon with some sort of binder. Then there are metal oxide parts like Welwyn WCR, which are made of ruthenium oxide. I have no idea how this compares sonically to NiCr thin film. Some like Phicomp for their PRC111 thick film resistors will only talk about resistive paste, leaving much to the user's imagination. Others, like Meggitt for their CR series will only talk about metal glaze, whatever that is.

I won't comment on megnetic properties...

Eric
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Old 20th August 2002, 11:06 AM   #10
tiroth is offline tiroth  United States
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PSP film caps are available in SMD, and Holsworthy makes their "Holco" resistors in 0805 10ppm 0.1%.
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