PCB effect

[John Larkin]

https://www.dropbox.com/s/xtx2shqg0mh3u5w/J740_Amp.jpg?raw=1

When I paved over the power pins of this part with solid copper, parts
of the pins became solder-mask-defined pads. That's fine here, where
all 4 pins are common. It could be tricky in other situations.

Layout software and PCB fab houses both take liberties with solder
masks. That can get serious for BGAs.

I kind of miss my old flip phone and kinda hate this fancy Samsung
thing, but it sure has a great camera. This was shot looking into my
Mantis, which is hard to do with a conventional big-lens camera.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Winfield Hill]

John Larkin wrote...

https://www.dropbox.com/s/xtx2shqg0mh3u5w/J740_Amp.jpg?raw=1

When I paved over the power pins of this part with solid copper, parts
of the pins became solder-mask-defined pads. That's fine here, where
all 4 pins are common. It could be tricky in other situations.

Layout software and PCB fab houses both take liberties with solder
masks. That can get serious for BGAs.

I kind of miss my old flip phone and kinda hate this fancy Samsung
thing, but it sure has a great camera. This was shot looking into my
Mantis, which is hard to do with a conventional big-lens camera.

R23 has a small pad and a big pad.


--
Thanks,
- Win

 

[John Larkin]

On 11 Mar 2020 14:27:52 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

John Larkin wrote...

https://www.dropbox.com/s/xtx2shqg0mh3u5w/J740_Amp.jpg?raw=1

When I paved over the power pins of this part with solid copper, parts
of the pins became solder-mask-defined pads. That's fine here, where
all 4 pins are common. It could be tricky in other situations.

Layout software and PCB fab houses both take liberties with solder
masks. That can get serious for BGAs.

I kind of miss my old flip phone and kinda hate this fancy Samsung
thing, but it sure has a great camera. This was shot looking into my
Mantis, which is hard to do with a conventional big-lens camera.

R23 has a small pad and a big pad.

Same effect, a mostly unintentional solder-mask-defined pad, caused by
the part pad being buried in a bigger piece of copper, in this case
the 50 ohm output trace. That's fine here. It's only 1 GHz or so.

This PCB is really the test case for our new enclosures, the ones that
replace the horrible Hammond boxes. It's (maybe) a 1 GHz
optical-electrical converter and if it works we may as well try to
sell it. It's the Tektronix feed-beside idea, separate AC and DC gain
paths combined late in the process.

It took forever to get the boards, coronavirus side effect.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Robert Baer]

Winfield Hill wrote:

John Larkin wrote...

https://www.dropbox.com/s/xtx2shqg0mh3u5w/J740_Amp.jpg?raw=1

When I paved over the power pins of this part with solid copper, parts
of the pins became solder-mask-defined pads. That's fine here, where
all 4 pins are common. It could be tricky in other situations.

Layout software and PCB fab houses both take liberties with solder
masks. That can get serious for BGAs.

I kind of miss my old flip phone and kinda hate this fancy Samsung
thing, but it sure has a great camera. This was shot looking into my
Mantis, which is hard to do with a conventional big-lens camera.

R23 has a small pad and a big pad.

R23 is polarized - 2/5 of the electrons go one way, and the other 3/5
go the other way. The bigger pad decreases electron crowding...