Footprints / Land Patterns - CTI respected in footprints?

CTI respected in footprints?

Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: Footprints / Land Patterns
Forum Description: [General or a CAD specific issues / discussions]
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=3123
Printed Date: 21 Nov 2024 at 10:38pm

Topic: CTI respected in footprints?

Posted By: StachowJ
Subject: CTI respected in footprints?
Date Posted: 20 May 2022 at 4:27am

Hi,

question to librarians mostly.

Do you respect CTI requirements in designed footprints?

Lastly I had a discussion in my organization about CTI for our products.

We mostly use CTI 400 for laminate, but silkscreen legend has CTI 175. This reduces the allowed electrical distance between two potentials on the board.

A good example is electrolytic capacitor, where entire negative side is covered with silkscreen.

Did you ever investigated such case?

Are you libraries common and PCB designers apply adjustments, or you design them specifically for plenty of requirements ?

I asked the question: when buying tiles for your new bathroom, do you expect getting ones with already cut holes for your water outlets or you drill it depends on needs at construction side? Silence as an answer.

What's your company's approach?

Replies:

Posted By: Tom H
Date Posted: 20 May 2022 at 8:14am

CTI has never been a consideration in land pattern (footprint) requirements in any IPC Standards.

https://www.raypcb.com/pcb-cti/" rel="nofollow - What is PCB CTI? - Printed Circuit Board Manufacturing & PCB Assembly - RayMing (raypcb.com)

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Posted By: StachowJ
Date Posted: 23 May 2022 at 2:04am

Thanks Tom,

Anyway, does someone consider CTI on the library level?

What's your general approach guys? Do you maintain it on PCB design level, or you implement it in the library?

Do you think is a good approach?

I am pushed to redesign my footprints according CTI requirements (like modify silkscreen legend from ElCap (negative pin marking).