PCB Libraries Forum Homepage
Forum Home Forum Home > PCB Footprint Expert > Questions & Answers
  New Posts New Posts RSS Feed - Dual Flat No-Lead (DFN 2-Pin) Non-Symmetrical
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Dual Flat No-Lead (DFN 2-Pin) Non-Symmetrical

 Post Reply Post Reply
Author
Message
JDPrymak View Drop Down
New User
New User
Avatar

Joined: 04 Apr 2013
Location: SC
Status: Offline
Points: 13
Post Options Post Options   Thanks (1) Thanks(1)   Quote JDPrymak Quote  Post ReplyReply Direct Link To This Post Topic: Dual Flat No-Lead (DFN 2-Pin) Non-Symmetrical
    Posted: 05 Apr 2013 at 5:58am
We need the land patterns to be non-symmetrical for a polar capacitor.  

Cathode plate is larger to allow greater heat dissipation, and polar mounting.
Back to Top
Back to Top
Tom H View Drop Down
Admin Group
Admin Group
Avatar

Joined: 05 Jan 2012
Location: San Diego, CA
Status: Offline
Points: 5717
Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2013 at 6:52am
Could you please attach a web-link to the datasheets?
 
Our programmers need to see what your request is. They don't want to assume anything.
 
Aside that, the new "Package Designer" will be released this weekend in V2013 and you can create many non-standard library parts. You can even import ASCII files with X,Y coordinates and pin names for padstack placement.
 
Back to Top
JDPrymak View Drop Down
New User
New User
Avatar

Joined: 04 Apr 2013
Location: SC
Status: Offline
Points: 13
Post Options Post Options   Thanks (1) Thanks(1)   Quote JDPrymak Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2013 at 8:12am
Here's a link to the T528 Low ESL. Facedown Tantalum Polymer Capacitors.

http://www.kemet.com/kemet/web/homepage/kechome.nsf/file/KEM_T2018_T528.pdf/$file/KEM_T2018_T528.pdf

The terminal dimensions are on page 4.  The pad dimensions on page 7 are for the W and Z case, to allow a low ESL connection to the PCB and to allow connection to competitor's three-terminal device. The competitor created a three-terminal device, but there are two cathode connections.  The cathode connection is broken into two to eliminate huge disparities in solder pod areas that could cause the larger cathode plate to lift chip and break anode pad connection.  On our 7343 device we have only two terminals, anode and larger cathode, but recommend using two solder pads for the cathode to eliminate the propensity to lift.  We do not believe that three solder pads are necessary for the smaller case devices.
Back to Top
Tom H View Drop Down
Admin Group
Admin Group
Avatar

Joined: 05 Jan 2012
Location: San Diego, CA
Status: Offline
Points: 5717
Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2013 at 12:49pm
You're correct that if you just want to use the Kemet Capacitor you do not need 3 pads.
 
 
And this land pattern is "over the top" detailed.
 
 
You can create a good Footprint using the "Molded Body" component family and then select the "Footprint" tab to enter the mfr. pad sizes and spacing.
 
I think the center pad "wings" are for the alternate part.
 
Back to Top
Humberto222 View Drop Down
New User
New User


Joined: 05 Apr 2013
Status: Offline
Points: 1
Post Options Post Options   Thanks (0) Thanks(0)   Quote Humberto222 Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jul 2013 at 7:48am
Did you mean Component tab ? .... to fill in there the lead dimensions
Back to Top
Tom H View Drop Down
Admin Group
Admin Group
Avatar

Joined: 05 Jan 2012
Location: San Diego, CA
Status: Offline
Points: 5717
Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jul 2013 at 12:02pm
You fill in the component dimensions in the "Component Tab"
 
You fill in the mfr. recommended pattern in the "Footprint Tab"
 
Stay connected - follow us! X - LinkedIn
Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.358 seconds.