PCB Libraries Forum Homepage
Forum Home Forum Home > Libraries > PCB Library Construction Guidelines
  New Posts New Posts RSS Feed - IPC-7351 SMD & PTH Reference Calculators
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

IPC-7351 SMD & PTH Reference Calculators

 Post Reply Post Reply Page  12>
Author
Message
Nick B View Drop Down
Admin Group
Admin Group


Joined: 02 Jan 2012
Status: Offline
Points: 1756
Post Options Post Options   Thanks (0) Thanks(0)   Quote Nick B Quote  Post ReplyReply Direct Link To This Post Topic: IPC-7351 SMD & PTH Reference Calculators
    Posted: 07 Jan 2013 at 2:35pm

Here are the latest Reference Calculators. Please note there are TWO (2), one is Surface Mount, and the other Plated Through Hole, also referred to as TH. (you need to be logged in, registration is absolutely free!)

IPC-7351 SMD Reference Calculator


Below is the is the PCB Library Expert PTH Reference Calculator:
 
Stay connected - follow us! Twitter - LinkedIn
Back to Top
jk-999 View Drop Down
New User
New User
Avatar

Joined: 12 Dec 2012
Status: Offline
Points: 1
Post Options Post Options   Thanks (0) Thanks(0)   Quote jk-999 Quote  Post ReplyReply Direct Link To This Post Posted: 02 Apr 2014 at 9:00am
Which equation is correct? Zmax=Lmin +2JT + SQRT((CL)² + (2*F)² + (2*P)²)   or 
                                        Zmax=Lmin +2JT + SQRT((CL)² + (F)² + (P)²)
 
IPC 7351A  uses the second equation. I believe the calculator is using the first equation.
 
Back to Top
Jeff.M View Drop Down
Admin Group
Admin Group


Joined: 16 May 2012
Location: San Diego
Status: Offline
Points: 371
Post Options Post Options   Thanks (0) Thanks(0)   Quote Jeff.M Quote  Post ReplyReply Direct Link To This Post Posted: 02 Apr 2014 at 12:44pm

Both are correct.

The difference is due to the definitions of the 'Placement' (P) and 'Fabrication' (F) tolerances.

IPC-7351 demonstrates them as a single value.  For example in their publication they use 0.10 mm for F and 0.20 mm for P (this is your 2nd equation).

We use plus-or-minus values where an equivalent F would be +/- 0.05 mm and P would be +/- 0.10 mm so they're doubled before squaring (this is your 1st equation).

Either way, the tolerances are the same and the result is the same.
Stay connected - follow us! Twitter - LinkedIn
Back to Top
Nick B View Drop Down
Admin Group
Admin Group


Joined: 02 Jan 2012
Status: Offline
Points: 1756
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

Stay connected - follow us! Twitter - LinkedIn
Back to Top
KevinA View Drop Down
New User
New User


Joined: 24 Oct 2017
Status: Offline
Points: 2
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

Back to Top
Tom H View Drop Down
Admin Group
Admin Group
Avatar

Joined: 05 Jan 2012
Location: San Diego, CA
Status: Offline
Points: 4839
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.
Stay connected - follow us! Twitter - LinkedIn
Back to Top
KevinA View Drop Down
New User
New User


Joined: 24 Oct 2017
Status: Offline
Points: 2
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.  


Back to Top
Tom H View Drop Down
Admin Group
Admin Group
Avatar

Joined: 05 Jan 2012
Location: San Diego, CA
Status: Offline
Points: 4839
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. 

Stay connected - follow us! Twitter - LinkedIn
Back to Top
IainSynaptive View Drop Down
New User
New User


Joined: 07 Jun 2016
Status: Offline
Points: 1
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,
Back to Top
Tom H View Drop Down
Admin Group
Admin Group
Avatar

Joined: 05 Jan 2012
Location: San Diego, CA
Status: Offline
Points: 4839
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. 

Stay connected - follow us! Twitter - LinkedIn
Back to Top
 Post Reply Post Reply Page  12>

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.059 seconds.