PCB Libraries Forum : Questions & Answers https://www.PCBLibraries.com/forum/ Thu, 21 May 2026 12:15:30 +0000 Thu, 21 May 2026 11:37:51 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.07 30 https://www.PCBLibraries.com/forum/RSS_topic_feed.asp?FID=34 <![CDATA[PCB Libraries Forum]]> https://www.PCBLibraries.com/forum/forum_images/PCBLForumLogo.gif https://www.PCBLibraries.com/forum/ <![CDATA[Questions & Answers : Inward L-Bend Terminal Leads for Pad Length]]> https://www.PCBLibraries.com/forum/inward-lbend-terminal-leads-for-pad-length_topic3646_post14541.html#14541 Author: Tom H
Subject: Inward L-Bend Terminal Leads for Pad Length
Posted: 21 May 2026 at 11:37am

The Inward L-Bend is similar to the J-Lead component family but with flat leads that bend inward. 

The E2 dimension is to the center of the terminal leads. You may have to do some math to figure that out. 

This component family and terminal lead are in the new Footprint Expert Guideline which will be released next week. 

]]> Thu, 21 May 2026 11:37:51 +0000 https://www.PCBLibraries.com/forum/inward-lbend-terminal-leads-for-pad-length_topic3646_post14541.html#14541 <![CDATA[Questions & Answers : Inward L-Bend Terminal Leads for Pad Length]]> https://www.PCBLibraries.com/forum/inward-lbend-terminal-leads-for-pad-length_topic3646_post14539.html#14539 Author: ransonjd
Subject: Inward L-Bend Terminal Leads for Pad Length
Posted: 21 May 2026 at 10:48am

What is used to calculate the pad length on parts with inward bent leads? 

(J-Lead, L-lead, PLCC, etc.) 

As far as I can see, the software doesn't provide a field for the measurement of the inward extent of the leads on these parts. (Like L on SOPs, but inward.)

Additionally, what is E2 supposed to measure on an L-lead part?

Thanks!
]]> Thu, 21 May 2026 10:48:19 +0000 https://www.PCBLibraries.com/forum/inward-lbend-terminal-leads-for-pad-length_topic3646_post14539.html#14539 <![CDATA[Questions & Answers : Collapsing vs: Non-Collapsing BGA Balls]]> https://www.PCBLibraries.com/forum/collapsing-vs-noncollapsing-bga-balls_topic1868_post14531.html#14531 Author: Tom H
Subject: Collapsing vs: Non-Collapsing BGA Balls
Posted: 12 May 2026 at 8:01am

The Non-Collapsing BGA calculator is used on fine pitch parts when you can't fanout all the pins in the PCB layout and you're only fanout option is via-in-pad. 

Non-Collapsing BGA pads are bigger then collapsing BGA pads to allow an annular ring for the drilling process. 

Also, if you need to solder mask define the BGA pad to pass drop tests, the solder mask will help with the pad attachment to the prepreg. During drop tests, the ball to pad joint will withstand a drop test, but a non solder mask defined pad could rip away from the prepreg causing the device to malfunction. 


]]> Tue, 12 May 2026 08:01:54 +0000 https://www.PCBLibraries.com/forum/collapsing-vs-noncollapsing-bga-balls_topic1868_post14531.html#14531 <![CDATA[Questions & Answers : Collapsing vs: Non-Collapsing BGA Balls]]> https://www.PCBLibraries.com/forum/collapsing-vs-noncollapsing-bga-balls_topic1868_post14530.html#14530 Author: m.elsayed
Subject: Collapsing vs: Non-Collapsing BGA Balls
Posted: 11 May 2026 at 8:29pm

Is the information on collapsing or non collapsing be mentioned in supplier datasheets?

Or does it just depend on the pin pitch value only?

Also is the pitch value found in IPC-7352 standard?

]]> Mon, 11 May 2026 20:29:25 +0000 https://www.PCBLibraries.com/forum/collapsing-vs-noncollapsing-bga-balls_topic1868_post14530.html#14530 <![CDATA[Questions & Answers : Master Options File or CAD Tool Translator Issue]]> https://www.PCBLibraries.com/forum/master-options-file-or-cad-tool-translator-issue_topic3637_post14512.html#14512 Author: Nick B
Subject: Master Options File or CAD Tool Translator Issue
Posted: 16 Apr 2026 at 5:24pm

If you experience one of these issues:
  1. Footprint Expert installation is overwriting your Master Options file, or
  2. CAD tool translator is not working correctly
It is probably because you are using the same OPT options file as both your "CAD tool translator" OPT file and "Master Options" file. These two are separate files. As a matter of fact, there are three OPT option files:


1. Console Options - edit in Tools > Options


2. Master Options - edit in Tools  > Options


3. CAD Tool Options - edit in the "Build Footprint" window

]]> Thu, 16 Apr 2026 17:24:43 +0000 https://www.PCBLibraries.com/forum/master-options-file-or-cad-tool-translator-issue_topic3637_post14512.html#14512 <![CDATA[Questions & Answers : How To Choose the Footprint for SMD Chip Resistor]]> https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14492.html#14492 Author: Tom H
Subject: How To Choose the Footprint for SMD Chip Resistor
Posted: 23 Mar 2026 at 8:46am

Here is the original EIA PDP-100 Chip Package dimensions and tolerances. 

https://www.pcblibraries.com/Forum/chips_topic3598.html

Compare with IEC.

]]> Mon, 23 Mar 2026 08:46:09 +0000 https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14492.html#14492 <![CDATA[Questions & Answers : How To Choose the Footprint for SMD Chip Resistor]]> https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14491.html#14491 Author: Ariel_Levy
Subject: How To Choose the Footprint for SMD Chip Resistor
Posted: 23 Mar 2026 at 12:58am

Tom thank you very much Smile
and thank you Feynman

My difficulty is in obtaining information the thickness of the contacts size of the component (the size "T")
I bought the IPC-7351 and 7352. and you don't have information about this.
I think to buy EIA-JEP95 , and don't know it's worth the money if very MFG design is contacts size what "he" want's.

This table i found is accurate?


How you handle this with general discrete components ,when the contacts size can be between 0.10 to 0.40?
With the IPC-7351 when contacts size is 0.4 mm?
]]> Mon, 23 Mar 2026 00:58:01 +0000 https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14491.html#14491 <![CDATA[Questions & Answers : How To Choose the Footprint for SMD Chip Resistor]]> https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14490.html#14490 Author: feynman
Subject: How To Choose the Footprint for SMD Chip Resistor
Posted: 22 Mar 2026 at 10:14am

Ask a/your assembler. They probably assembled millions of parts and are probably the best source for a reliable footprint.]]> Sun, 22 Mar 2026 10:14:58 +0000 https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14490.html#14490 <![CDATA[Questions & Answers : How To Choose the Footprint for SMD Chip Resistor]]> https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14489.html#14489 Author: Tom H
Subject: How To Choose the Footprint for SMD Chip Resistor
Posted: 22 Mar 2026 at 8:14am

IPC-7351 uses Min/Max Mode technology. the resulting footprint takes into consideration the package tolerances to calculate the pad stacks. The solder pattern should accommodate the package in the minimum, nominal and maximum material condition. 

The average 0402 tolerance range is +/-0.05 to +/-0.10. 

It seems like component manufacturers use their nominal package dimensions and add a Toe, Heel and Side. They use Nominal Mode technology and ignore the tolerances they provide in their datasheets. 

The average dimensions on an 0402 are L=1.00, W=0.50, T=0.25. 

Your pad stack pattern will depend on what dimensions and tolerances you use. 

However, if you run into a 0402 chip manufacturer that has tolerances greater than 0.10, I would highly question the accuracy of their machine process. 

Ideally, manufacturers try to produce packages that are Nominal Material Condition. That's the goal. Maybe in the future package tolerances will be 0.00 and then the Nominal Mode technology will take over and the IPC-7351 mathematical model will be history. 

]]> Sun, 22 Mar 2026 08:14:56 +0000 https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14489.html#14489 <![CDATA[Questions & Answers : How To Choose the Footprint for SMD Chip Resistor]]> https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14488.html#14488 Author: Ariel_Levy
Subject: How To Choose the Footprint for SMD Chip Resistor
Posted: 22 Mar 2026 at 5:07am

How do you choosethe footprint for SMD Resistor case 0402?

Vishay have3 recommendations for footprints.

Yageo onerecommended but it’s different from Vishay.

Vishay recommendation:

L=0.50 A=0.40 B=0.60

BASED ONIPC-7351

L=0.40 A=0.55B=0.60

BASED ON IEC 61188-6-2

L=0.55 A=0.35B=0.55

Yageo

L=0.50 A=0.50 B=0.60

 

I am very confused by all the recommendations.

I would appreciate a suggestion or any guidance on how to choose a footprint.


]]> Sun, 22 Mar 2026 05:07:04 +0000 https://www.PCBLibraries.com/forum/how-to-choose-the-footprint-for-smd-chip-resistor_topic3630_post14488.html#14488