🚀 go-pugleaf

"Shaun" <not.today@go.away.au> wrote in message 
news:4a68395a$0$3253$afc38c87@news.optusnet.com.au...
>
> "Robert Baer" <robertbaer@localnet.com> wrote in message 
> news:ttqdnac-5O96jPXXnZ2dnUVZ_sidnZ2d@posted.localnet...
>> David L. Jones wrote:
>>> An interesting question was posted on another forum:
>>> "can you get (ceramic) SMD caps (1206,0805 etc) with the values printed 
>>> on them?".
>>>
>>> My first response was that I've very rarely seen this (like maybe once), 
>>> and while it is possible (see 
>>> http://www.synrad.com/search_apps/application_briefs/117-2.htm), you 
>>> basically can't get labeled ones, they are almost always without 
>>> markings.
>>>
>>> It got me to thinking, why is it so?
>>> My guess would be that it's due to the surface finish (or lack thereof) 
>>> on ceramic capacitors, and/or the delicate nature of their multi-layer 
>>> construction means they could be more easily damaged or properties 
>>> altered by the process.
>>> As opposed to most SMD resistors that have a coating on them which would 
>>> allow for easy and accurate printing using various technologies.
>>>
>>> Any know the real reason(s) why ceramic SMD caps don't have markings?
>>>
>>> Dave.
>>   Ahh..the caps could likewise be coated (and AFAIK they .are. coated 
>> prior to potting for leaded versions).
>>   Then, given that coating, they could be marked like the resistors you 
>> mentioned.
>>   BUT..that was "never" done so it will not be done (gotta stay in that 
>> rut...).
>
> I doult very much any manufacter would coat SMD caps as it would increase 
> the height to capacitor sits above the board, increasing the mounted 
> inductance, a crital factor when designing high frequecny boards. 
> Manufactuers spend a lot of money trying to reduce this unwanted property.
>
> see http://www.avx.co.il/docs/techinfo/licadesign.pdf
> or 
> http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/D1A54E16FEC61B058525721E006EF53C/$file/Sun%20Paper%20on%20ESL%20&%20ESR.pdf
> although these articles deal with via placement they discuss the need to 
> reduce the size of the loop that current flows in, a loop that would be 
> increased if a capacitor had an extra coating on it.
>
>

Coating or encapsulation? Coating could be insignificantly thin.