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IPC-7351 SMD & PTH Reference Calculators

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dfournier View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dfournier Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jul 2018 at 5:24am
Hello Tom,

Thank you for informations.

Does IPC define Thermal ID and OD? I don't find explanation that define these diameters.
I use CADSTAR software and Thermal ID and OD are differently defined.


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Tom H View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jul 2018 at 7:32am
Thermal Relief is for all PTH pins that connect to a Plane. 

A PTH lead with a direct connection to a GND or VCC Plane can have a cold solder joint because the plane can dissipate all the heat from that connection. 

ID = Inside Diameter of Plane Pad

OD = Outside Diameter of Plane Pad

The thermal ID & OD are connected with Spokes from the pad to the copper plane. 
 

 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dfournier Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jul 2018 at 12:09am
Hello guys,

I start to create footprints with IPC-7351.
Could you tell me what are Thermal ID and Thermal OD for PTH?
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan 2018 at 2:55pm
IPC-7351 has no recommendation on using circular pad shape for Chip Components. 

The best source for this recommendation would be the Assembly Shop source that you are currently using. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote IainSynaptive Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jan 2018 at 2:32pm
Good evening and Thank you for Everything you've created here!

I have simple a question regarding Chip components and Circular Pads: Are they acceptable?

I've been unable to locate any published Pros/Cons to this method and PC-7351B doesn't offer any guidelines to this practice.

Are you able to provide any insight?

Thank you in advance,
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 24 Oct 2017 at 3:11pm
The Rectangular End Cap Side Goals need to be addresses in 7351 because Resistors only have metal Terminals on 3 sides and do not (cannot) have a side fillet. But Chip Capacitors have metal Terminals on 5 sides and a side fillet is a reality. 

IPC-7351 is no longer a Standard (even though the cover of IPC-7351B says so). 

IPC-7351 is now a "Guideline" and should be used as such. Land Pattern pad size and spacing are flexible and not rigid hard core values. 

The IPC-J-STD-001 Standard for solder joint goal acceptability is the ruling standard for Land Patterns and it has a higher priority over IPC-7351. 

PCB Libraries "Library Expert V2017" solder joint goals for Toe, Heel and Side values reflect IPC-J-STD-001 and not IPC-7351B. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KevinA Quote  Post ReplyReply Direct Link To This Post Posted: 24 Oct 2017 at 3:01pm
That made a differance (User data in the WHITE fields :)) but I still ended up with a .62 for pitch meaning .38 gap between the pads of a device who's overall length is .25, they don't have a diamensional tolerance until type 063. Toe=0.05 heel=-0.03 side=-0.03 

The other thing I've noticed is the manufactures have smaller pads with no side compared to any version of IPC-7351, unless they are Kemet, Kemet uses IPC-7351 but no version shown.  


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 24 Oct 2017 at 12:36pm
You need to adjust the Toe & Heel values. The Chip component does not have a 0.35 mm Toe and Heel. 

Download the PCB Libraries Solder Joint Goal tables here - 

Open this Excel spreadsheet - Library Expert Solder Joint Goal Tables.xlsx

Select - "Rectangular End Cap" component family in the Excel Spreadsheet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KevinA Quote  Post ReplyReply Direct Link To This Post Posted: 24 Oct 2017 at 12:22pm
Downloaded the Calculator and tried it but I must be doing something wrong or my math is punked:

From TAIYO YUDEN:



I added B+A+B = L for Min and MAX



and ended with this:



Thanks

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nick B Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 2014 at 12:53pm

Please note the IPC-7351 Reference Calculator was just updated! There is now an Inserted Mount "IMD" (TH) Reference Calculator. Download it from this forum thread, or from www.PCBLibraries.com/downloads

Nick

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