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Expected pick and place precision for 0603 LEDs?

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#71378

Expected pick and place precision for 0603 LEDs? | 12 November, 2013

Hi Folks,

I'm working on a LED display that is composed of multiple layers. What is interesting for the point of this discussion is the PCB layer and the light deflector layer on top of it. Please take a look at the related pictures at http://plus.google.com/photos/106435362157390351263/albums/5945495319660646913

In order for me to design large enough holes in the deflector layer I have to know the expected placement precision of the LEDs on the PCB. They have 0.8mm x 0.8mm sized pads and there's a 0.7mm distance between them. The exact part can be seen at http://www.digikey.com/product-detail/en/LS%20Q976-NR-1/475-2512-1-ND/1802639

Thank you very much in advance!

Laci

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#71383

Expected pick and place precision for 0603 LEDs? | 13 November, 2013

With what machine? I cannot help until that is disclosed.

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#71384

Expected pick and place precision for 0603 LEDs? | 13 November, 2013

Good question :)

I'd say with a machine that is available for an average pick and place operator nowadays. Our manufacturer is not fixed yet, that's why I don't have any specific.

On a related note I'm wondering whether the machine is so important given that the surface tension is supposed to pull the components to place (to some degree). Am I not right?

Thanks!

Laci

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#71385

Expected pick and place precision for 0603 LEDs? | 13 November, 2013

I would expect any half decent machine to place 0603 parts slap bang on target to the typical defined accuracy for such parts on most machines of perhaps ~60 microns or better. Self correction during reflow is IMHO much less pronounced with lead-free than was the case with leaded solders. If alignment is important you should pay special attention to your layout to keep it thermally balanced, never rely on self correction. Also your manufacturer will pay close attention to stencil design and pasting parameters/accuracy.

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