> -----Original Message-----
> From: Dehoyos, Ramon
> Sent: Monday, August 18, 2003 12:41 PM
> To: [log in to unmask]
> Subject: RE: [TN] placement verification of uBGA
>
>
>
>
>
>
>
> Hal:
> Do you know the component's body tolerances?
> Regards,
> Ramon
>
>
> -----Original Message-----
> From: Hal Winslow [SMTP:[log in to unmask]]
> Sent: Monday, August 18, 2003 10:22 AM
> To: [log in to unmask]
> Subject: Re: [TN] placement verification of uBGA
>
> Steve (and others...),
> I would caution you about using a silkscreen pattern to align
> components. Keep in mind that the silkscreen operation is only loosely
> aligned (probably +/- .005") to the circuitry patterns on the board, which
> is what you want your components aligned to. This might be too much of a
> tolerance, especially if it is truly a uBGA you are placing.
>
> Putting down the "chevrons" you mention would be the correct method,
> since they are perfectly aligned to the pads that your component is being
> placed on, since they are created during the same etching process.
>
> Hal
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of
> Steve Gregory
> Sent: Friday, August 15, 2003 5:56 PM
> To: [log in to unmask]
> Subject: Re: [TN] placement verification of uBGA
>
>
> Hi Larry!
>
> Something I've seen done before, is to either have a
> silkscreened outline of the part put on the board, or more recently with a
> board we built here, have "placement cheverons" etched into the board at
> the 4-corners of the device. Go to:
>
> http://www.stevezeva.homestead.com
>
> and look at "Placement Chevrons". Of course these have to
> match the outline of the body of the part, but the operators can easily
> tell visually, if the part is placed accurately or not....pretty slick if
> you ask me. But you do have a battle getting the designers to incorporate
> something like that.
>
> -Steve Gregory-
>
>
>
>
>
> I'm wondering what you all use for placement
> verification of uBGA? Before running a new setup, we take a solder sample
> PCB and put double sided tape on it. Place the components on the PCB, when
> its finished the machine operator hauls the PCB over to the techs for them
> to Ersa and xray it to verify placement accuracy of the uBGA. I'm looking
> for something which would allow the machine operator to verify the
> placement themselves. Purchasing additional Ersa and xray equipment
> wouldn't be an option. Any suggestions?
>
> Larry
>
>
>
>
>
> -Steve Gregory-
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