Probably to keep out light, which could affect the operation of the semiconductor devices.
The epoxy resin is not inherently black.
The epoxy resin is not inherently black.
Not always black. I am pretty sure I've seen white opto-chips. I think it was either a opto-triac or opto-fet switch. But agree with rayma, light affects transistors. Opto-electronics wouldn't exist if it did not.
Early glass-cased semis were sometimes covered with black paint to reduce the effect of light.
Probably with mixed results.
https://www.ebay.com/itm/124738742011
Probably with mixed results.
https://www.ebay.com/itm/124738742011
D
Deleted member 550749
Lamp black/soot is cheapest lightest non fading dye, so it´s very popular everywhere (include speaker cones in that).
And blocking light is a desirable quality
Back in the day In used to scratch OC71 paint off to make a photo transistor.
And blocking light is a desirable quality
Back in the day In used to scratch OC71 paint off to make a photo transistor.
Audio component manufacturers have missed a trick there. Different colours of same opamp. About 10 minutes later there'd be people claiming the green version had more pace or rythm than red and paying twice as much for it.
Black is an easy colour to get. Also if you want to print on it that's easy too
Black is an easy colour to get. Also if you want to print on it that's easy too
Black, green & white. Like cars and vinyl records in any colour you like.
Are ceramics considered brown? I've seen light gray too, long ago.
Are ceramics considered brown? I've seen light gray too, long ago.
D
Deleted member 550749
If there's no way of UV getting to them then fine, but since carbon black has to be the least expensive opacity agent, why make them anything other than black? Not even the geekiest among us cares, do they?
Epoxy (Novolak) can be colored in many ways (red, green, white, etc.): for opto-couplers, some exist in two variants. The white one has a slightly better transfer ratio, but a lower immunity to ambient light and the black one has opposite properties.
The natural color of epoxy, without any colouring or filler is an unattractive, dirty translucent tone, and it lets some light in, which is generally undesirable
The natural color of epoxy, without any colouring or filler is an unattractive, dirty translucent tone, and it lets some light in, which is generally undesirable
I was once probing a CMOS chip (requires a microscope and a micromanipulator probe). The chip was doing what it ought to do, considering the loading effects of the probe. I made the mistake of turning on the probe station light while the chip was powered up. That was the end of that chip.
I wonder if radiation of heat is a reason for black?
I wonder if radiation of heat is a reason for black?
I've seen plenty of white ceramic body mil spec dip ICs, most were likely 1970s vintage.
@Wik There are IC packages with a little entertainment window... lookie lookie carefully and you maybe can see the electrons jumping around.
:🙂
:🙂
Years ago, my co-workers had a strange problem with their prototype. It turned out that they had not covered the window on an EPROM, which was photo sensitive.