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 Posted: Apr 03, 2012 - 08:30 AM |
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Joined: Feb 16, 2007
Posts: 698
Location: Israel
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| These devices come in non-standard (god,why???) VQFN packages (detailed can be seen here: http://www.atmel.com/System/Overlay/PackageAttributes.aspx?uri=tcm:26-19456) that are not available in any Eagle library I searched in, also could not found a recommended PCB footprint with Google. If someone would like to share the PCB footprint I will be very grateful and sure other will find it very usable! |
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Posted: Apr 03, 2012 - 10:04 AM |
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Joined: Jul 27, 2001
Posts: 7429
Location: St. Leonards-on-Sea (UK)
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| If you can get hold of the footprint details it should only take you a few minutes to create it. Atmel support should be able to make it available. |
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Leon Heller
G1HSM
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Posted: Apr 03, 2012 - 10:45 AM |
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Joined: Feb 16, 2007
Posts: 698
Location: Israel
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leon_heller wrote:
If you can get hold of the footprint details it should only take you a few minutes to create it. Atmel support should be able to make it available.
I have no problem creating my own footprint from a datasheet or other source, however I could find any as this is an uncommon package.
Regarding Atmel support, I did contact them prior to posting in the forum and they supplied a DXF file with what they called "... a footprint that we use for in-house production. This is by no means a standard or recommended footprint."
I included a part of the screen-capt. from SolidWorks. This is not really what I was looking for to be honest... |
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Posted: Apr 03, 2012 - 10:54 AM |
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Joined: Jul 27, 2001
Posts: 7429
Location: St. Leonards-on-Sea (UK)
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| You might have to design the footprint yourself, then, from scratch. |
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Leon Heller
G1HSM
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Posted: Apr 03, 2012 - 11:07 AM |
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Joined: Feb 16, 2007
Posts: 698
Location: Israel
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Sure why not, I'll give that a go...
While I'm at it, a rant!
Why Atmel uses a non-standard case for some of these sensors? And if there's a reason for this why on earth not include a recommended PCB footprint in the datasheet like others do. Also, the QTouch library could use much MUCH better documentation available.
done, sorry. |
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Posted: Apr 03, 2012 - 12:54 PM |
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Joined: May 01, 2003
Posts: 577
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| Was the footprint inherited from the previous company that designed/owned all the Qtouch patents ? |
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Posted: Apr 03, 2012 - 07:30 PM |
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Joined: Feb 16, 2007
Posts: 698
Location: Israel
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chartman wrote:
Was the footprint inherited from the previous company that designed/owned all the Qtouch patents ?
The AT42QT1040 looks very much like the Quantum QT240-ISSG but used to be in SSOP20 case... |
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Posted: Apr 03, 2012 - 07:46 PM |
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Joined: Feb 16, 2007
Posts: 698
Location: Israel
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| OK some good news! I contacted Atmel again saying it's not reasonable not to provide any data for the footprint and they sent me a footprint file for Altium. I don't have Altium and never worked in a company that had it but here it is for anyone who might be able to make some use of it. I will try to get an app in order to view it. |
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Posted: Apr 03, 2012 - 09:31 PM |
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Joined: Feb 19, 2003
Posts: 2233
Location: Seattle, WA
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slow_rider wrote:
OK some good news! I contacted Atmel again saying it's not reasonable not to provide any data for the footprint and they sent me a footprint file for Altium. I don't have Altium and never worked in a company that had it but here it is for anyone who might be able to make some use of it. I will try to get an app in order to view it.
Just looked at it - it's pretty simple. pitch of pads is 0.45mm, looks a lot like a QFN. Center pad is 1.8x1.8mm. Outer pads are 0.2x0.65mm with rounded ends (0.65 includes the length of the rounded part). Vertical distance from center of center pin to center of top pins (or bottom pins) is 1.525mm. They seem to be using 4 mil soldermask expansion (the default in Altium Designer) which leaves some really thin webbing.
Hope this helps. |
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Posted: Apr 04, 2012 - 08:13 AM |
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Joined: Feb 16, 2007
Posts: 698
Location: Israel
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| That helps a lot! I'll try and get this footprint done in Eagle and upload it! |
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Posted: Apr 04, 2012 - 10:05 AM |
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Joined: Feb 16, 2007
Posts: 698
Location: Israel
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| Here is an Eagle footprint I did real quick. If anyone wants to double check it, won't hurt. |
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Posted: Apr 04, 2012 - 01:22 PM |
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Joined: Jul 02, 2005
Posts: 5951
Location: Melbourne, Australia
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Hi.
Thanks for sharing. If I have any comment it would be to say that you shouldn't allow silk screening to be on the solder pads.
Cheers,
Ross |
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Ross McKenzie
ValuSoft
Melbourne Australia
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Posted: Apr 04, 2012 - 01:31 PM |
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Joined: Feb 16, 2007
Posts: 698
Location: Israel
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valusoft wrote:
Hi.
Thanks for sharing. If I have any comment it would be to say that you shouldn't allow silk screening to be on the solder pads.
Cheers,
Ross
I'll explain... The marking that you can see overlapping the solder pads is on layer 51 which is the physical outline layer for Eagle PCB editor (helps visualize the actual package when doing layout). This layer is not normally transferred to the silk screen, for this I made a second outline on layer 21 which has a thicker line (to meet fab house minimum requirements) + it's not very close to the solder pads so even if the silk screen is a little off (usually is) the pads will probably be clear. |
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Posted: Apr 04, 2012 - 02:56 PM |
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Joined: Jul 02, 2005
Posts: 5951
Location: Melbourne, Australia
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OK. Understood ... that's what happens when I have a very quick look just to be able to give you some feedback before my bedtime ... which is now overdue 
Cheers,
Ross |
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Ross McKenzie
ValuSoft
Melbourne Australia
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