[SI-LIST] Re: IC package

  • From: Ray Anderson <reanderson@xxxxxxxxxxxxx>
  • To: si-list@xxxxxxxxxxxxx
  • Date: Tue, 17 Aug 2004 09:20:27 -0700

Hal Murray wrote:

>>Black was also cheaper to make before, (remember mostly black and grey
>>plastics only)
>>    
>>
>
>I assume the basic answer is cost.
>
>Clear plastic is available for LEDs and photo receptors - other 
>colors/filters too.  Anybody have an estimate as to how much more non-black 
>costs?
>
>
>  
>
Another reason for black (or other photo opaque color) other than clear 
is that ambient light shining on the die can have 'unintended 
consequences' . I remember a couple cases a long time ago where in one 
instance ambient light shining through the 'erase' window on an EPROM 
somehow changed timing enough to crash a system (covering the window 
with black tape restored normal functionality). In another case 120Hz 
noise was modulated onto some driver outputs in a de-lidded chip we were 
working on in the lab. Shielding the die from the ambient fluorescent 
lighting made the 120Hz nose on the outputs go away.

-Ray

------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl?Si-List_FAQ

List technical documents are available at:
                http://www.si-list.org

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  

Other related posts: