Author Topic: RGB fid cam illumination ?  (Read 492 times)

spiyda

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RGB fid cam illumination ?
« on: June 28, 2018, 08:48:35 PM »
I use a variety of board types, currently aluminium with a white dielectric layer,

The FID cam has a real problem seeing the fiducials for auto correction.
The bare copper ( yes I know ) pads seems to reflect the red FID cam illumination almost the same as the dielectric ( copper is red)
Has anyone had the same problem and solved it ?

I'm thinking of changing the FID cam illuminator to RGB LEDs so I can adjust the colour to get the greatest contrast.
I know the illuminator will come out without disturbing the camera positon, and even if that wasn't the case, the leds could be mounted on a ring outside the camera case.

Before I waste any time on this I thought I'd ask

Do the much brighter white illuminators I know some folks have built have better contrast in theis situation ?

Is the camera sensitive to light other than red ?

Thoughts anyone ?


Mike

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Re: RGB fid cam illumination ?
« Reply #1 on: June 28, 2018, 11:50:04 PM »
Certainly worth a try - easy enough to hold some LEDs in the vicinity to see what difference it makes before diving in with fixing them.
The camera is a normal monochrome camera so should l have some sensitivity at green & blue ( also IR - might be worth a try)
 

spiyda

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Re: RGB fid cam illumination ?
« Reply #2 on: June 29, 2018, 12:01:27 AM »
Certainly worth a try - easy enough to hold some LEDs in the vicinity to see what difference it makes before diving in with fixing them.
The camera is a normal monochrome camera so should l have some sensitivity at green & blue ( also IR - might be worth a try)
So why didn't I think of that ! 
Sticker over the illuminator, Load a job, omit all the feeders and auto fid whilst aiming LEDs..  simples !

Mike

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Re: RGB fid cam illumination ?
« Reply #3 on: June 29, 2018, 07:28:34 AM »
The thing about using bright illumination is it reduces the effect of ambient light so things work more consistently ( really must get round to doing this for my flying cam). Also reduces camera noise.
The fid cam is less controllable than the up-facing one, so harder to reduce the sensitivity for brighter lighting - probably need to add a ND filter over the lens.
As fids are often shiny, small changes in angle of lighting etc. can make a big difference. I never use auto-fid as I always need to do manual offsets, but sometimes find I need to shade the board to get a clear view of the fid.
 

spiyda

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Re: RGB fid cam illumination ?
« Reply #4 on: June 29, 2018, 06:52:47 PM »
Well, that was interesting, !

I have a particular need for the auto fid correction for the current jobs.

discrete circular aluminium pcbs with the only hole in the centre, so nothing to fix the rotation.
They are a PITA to get exactly right in the jig every time.


Re the illumination, I tried Green, Blue, U/V and IR

What I found was that contrary to what I thought, the reflective copper is the light colour, the matt finish white dielectric of the board is the dark colour.

Anything but red reduced the brightness of the copper

Maximum contrast was achieved with minimum ambient light, and adjusting the height of the board to the best position for fid cam focus.

So leave it well alone  :D

At least I know now..   with the lid down, I have an adjustment of about 3 either side of the optimumthreshold setting.

phonoplug

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Re: RGB fid cam illumination ?
« Reply #5 on: July 03, 2018, 10:07:03 PM »
Sorry, slightly off topic but picking up on another point you mentioned - building circular boards.

I build similar round boards from time to time. For larger ones that do not get panelised I add a couple of 'ears' - primarily added to aid paste application with a stencil (as initially many are hand placed due to low volume) but also helps equally with putting into the machine in a consistent position. Ears can easily snap off later and reminants be ground off with a linisher.

Mike

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Re: RGB fid cam illumination ?
« Reply #6 on: July 05, 2018, 10:36:00 AM »
For boards where no tabs must extend outside the outline, I usually use rat-bites, offset into the board, so any remnants stay inside the outline.

spiyda

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Re: RGB fid cam illumination ?
« Reply #7 on: July 08, 2018, 11:39:13 PM »
Mine are aluminium boards punched on flypresses after etching , so no luxury of tabs