Hi!
I'm looking for polypropylene "compatible" SMD caps. I gather that polyester is the only material so far. Anyone who knows more?
I'm looking for polypropylene "compatible" SMD caps. I gather that polyester is the only material so far. Anyone who knows more?
peranders said:
Not sure what you mean by "compatable." But other than polyester there's also stacked polyphenylene sulfide (PPS) and polyehtylene napthalate (PEN) films available.
se
Polyphenylene sulfide poped into my mind after my post, but the second one I have heard but not rescently.
I'm looking good caps equally good as polypropylene and also 5% or better.
I'm looking good caps equally good as polypropylene and also 5% or better.
I am currently trying Wima SMD2200 polyester caps, too early to give an opinion yet, but for those that follow such things, they seem to be completely non-magnetic😉
Panasonic makes PPS caps in SMD style.
I typed "panasonic PPS" into google; got this:
http://www.digikey.com/scripts/us/dksus.dll?Criteria?Ref=52979&Cat=30409424
Is PPS really as good as polypropylene? I think the panasonic PPS caps are rated to have about twice the DF as PP. Still probably better than polyester!
I typed "panasonic PPS" into google; got this:
http://www.digikey.com/scripts/us/dksus.dll?Criteria?Ref=52979&Cat=30409424
Is PPS really as good as polypropylene? I think the panasonic PPS caps are rated to have about twice the DF as PP. Still probably better than polyester!
OT- Polyethylene Napthalate
PEN is one of the best vapor barrier resins availabe. It's a little more difficult to make than PET (polyester terephthalate -- which we think of as DuPont's mylar.)
At some point PEN may replace glass in packaging of consummable -- it's lighter weight, unbreakable, excellent vapor barrier properties, recyclable etc. If this ever happens it would be a boon to the price of high quality SMD capacitors.
PEN is one of the best vapor barrier resins availabe. It's a little more difficult to make than PET (polyester terephthalate -- which we think of as DuPont's mylar.)
At some point PEN may replace glass in packaging of consummable -- it's lighter weight, unbreakable, excellent vapor barrier properties, recyclable etc. If this ever happens it would be a boon to the price of high quality SMD capacitors.
I have talked to WIMA folk about PPS. It
would appear to have properties as good as
or better than Polypropylene. Temperature
coefficient is better. They stopped short
of saying it would be better for critical
sample/hold circuits. In my experience a
cap that works well in critical S/H applications
works well for audio.
The problem with SMT film caps is that
the plastic melts when they get hot. This
instantly limits your choices for film
dielectrics.
I don't know anything about PEN, though
the Panasonic pages in Digi-key would
suggest that PPS is the better of the two.
I'd give PPS a try, but be VERY careful
with your soldering technique.
would appear to have properties as good as
or better than Polypropylene. Temperature
coefficient is better. They stopped short
of saying it would be better for critical
sample/hold circuits. In my experience a
cap that works well in critical S/H applications
works well for audio.
The problem with SMT film caps is that
the plastic melts when they get hot. This
instantly limits your choices for film
dielectrics.
I don't know anything about PEN, though
the Panasonic pages in Digi-key would
suggest that PPS is the better of the two.
I'd give PPS a try, but be VERY careful
with your soldering technique.
I think I will use "Metallized polyphenylene sulphide (PPS) SMD", Evox Rifa for my SMD headphone project with OPA134/OPA627 and BUF634 (all SMD). The capacitor is for input coupling otherwise the amp will be DC coupled.
http://www.elfa.se/elfa/produkter/se/20/2023233.htm
http://www.elfa.se/elfa/produkter/se/20/2023233.htm
Attachments
PPS caps
PPS caps are very good, but please heed this warning.
When I was involved in desiging an 800MHz transceiver some time ago, we used these for the first time.
The prototype boards (hand soldered) experienced lots of failures in the PPS caps, some latent.
These components reflow well, but you need tight temperature / time control to fit them by hand - be quick and you'll be OK.
Andy.
PPS caps are very good, but please heed this warning.
When I was involved in desiging an 800MHz transceiver some time ago, we used these for the first time.
The prototype boards (hand soldered) experienced lots of failures in the PPS caps, some latent.
These components reflow well, but you need tight temperature / time control to fit them by hand - be quick and you'll be OK.
Andy.
Peranders
Sorry, wasn't very clear - the PPS caps were primarily used as parts of filters (e.g. PLL loop filter, receiver Bessel filter etc.)
The RF decoupling was via the normal choice at these frequencies (ceramic / tantalum).
Andy.
Sorry, wasn't very clear - the PPS caps were primarily used as parts of filters (e.g. PLL loop filter, receiver Bessel filter etc.)
The RF decoupling was via the normal choice at these frequencies (ceramic / tantalum).
Andy.
Check out the SMD plastic caps at the fron of the pcb. My first SMD audio project. What do you think?
The sound is much much faster through the amp because of the small dimensions
.....
I'm only joking
Anyway, it works good!
The sound is much much faster through the amp because of the small dimensions
.....
I'm only joking Anyway, it works good!
Per: I have used SMD PPS caps for power supply bypasses, noise filtering, and stability compensation. They have worked fine for these purposes, but I have not tried them for signal coupling.
My production experiences reflect Andy's - these caps are best applied via cream solder. They can be installed with hand equipment, but tight temperature control and deft soldering techniques will be required. Once they are on, it will be difficult to remove them without having them disintegrate - especially the smaller sizes (below 1000pF).
Per, congratulations on your board. It looks pretty decent. The push-in power connectors that you chose look huge, however. I think that Berg offered some SIP connectors that were compact and suitable for power supply duties (I used to use them in production). And if you need local power supply decoupling to augment the electrolytics, a 0.1uF PPS SMD cap works well.
BTW, what are the two forward 5-pin SMD power ICs? Output buffers?
regards, jonathan carr
My production experiences reflect Andy's - these caps are best applied via cream solder. They can be installed with hand equipment, but tight temperature control and deft soldering techniques will be required. Once they are on, it will be difficult to remove them without having them disintegrate - especially the smaller sizes (below 1000pF).
Per, congratulations on your board. It looks pretty decent. The push-in power connectors that you chose look huge, however. I think that Berg offered some SIP connectors that were compact and suitable for power supply duties (I used to use them in production). And if you need local power supply decoupling to augment the electrolytics, a 0.1uF PPS SMD cap works well.
BTW, what are the two forward 5-pin SMD power ICs? Output buffers?
regards, jonathan carr
Component spotters 'r' us
They'll be the BUF634's, current-feedback unity gain buffers.
I've got a similar project to that on the go too, different front end op-amp though.
Per,
Is that the Jung-style multliloop feedback configuration?
Andy.
P.S. it will sound even better if you get those transformers away ....😉
They'll be the BUF634's, current-feedback unity gain buffers.
I've got a similar project to that on the go too, different front end op-amp though.
Per,
Is that the Jung-style multliloop feedback configuration?
Andy.
P.S. it will sound even better if you get those transformers away ....😉
Thanks Andy. You must have a better CRT than I do. 😉
>Is that the Jung-style multliloop feedback configuration?<
Andy, is that panting sound coming from you, or me?
best, jonathan carr
>Is that the Jung-style multliloop feedback configuration?<
Andy, is that panting sound coming from you, or me?
best, jonathan carr
Panting...
It's funny how a few components can get me excited
Andy.
BTW Per, make sure they're set to wide-bandwidth mode too...
It's funny how a few components can get me excited
Andy.
BTW Per, make sure they're set to wide-bandwidth mode too...
Re: Panting...
I have made two options, medium bandwidth and high with a jumper.ALW said:BTW Per, make sure they're set to wide-bandwidth mode too...
Thanks. The pcb has groundplane also but I gather that you already have figured out this?jcarr said:
Wago cage clamp connector are very good and huge if you compare but they are quite ordinary with pitch 0.2" or 5 mm at the same time! They can be pulled apart 0.08 mm per pole!
Re: Component spotters 'r' us
Those transformers have a special purpose besides delivering power, they radiate a magnetic field which add tube sound to the amp and in the same time remove dark yellow electrons from the center of the pcb where they are created. My goal was to feed the pcb with only bright yellow electrons.ALW said:
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