Author Topic: LQFP32 & LQFP44 IPC land patterns needed  (Read 429 times)

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Online Circlotron

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LQFP32 & LQFP44 IPC land patterns needed
« on: April 08, 2019, 05:14:21 pm »
Looked and looked for these. Could someone post up a diagram please? Is QFP the same footprint as LQPF?
 

Offline T3sl4co1l

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Re: LQFP32 & LQFP44 IPC land patterns needed
« Reply #1 on: April 08, 2019, 05:33:34 pm »
They're not in the datasheet?

What EDA?

Tim
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Online Circlotron

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Re: LQFP32 & LQFP44 IPC land patterns needed
« Reply #2 on: April 08, 2019, 07:40:41 pm »
Not that I can see.
https://www.nxp.com/docs/en/reference-manual/MC9S08PA16RM_Rev.1.pdf
I used to have an IPC land pattern book but I've lost it.
 

Offline Siwastaja

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Re: LQFP32 & LQFP44 IPC land patterns needed
« Reply #3 on: April 08, 2019, 08:58:16 pm »
That's a reference manual. It's for a system designer and programmer. You need the datasheet. It's necessary for electrical design, including schematics and layout.

First result in Google:
https://www.nxp.com/docs/en/data-sheet/MC9S08PA16_Rev.1.pdf

Though, unlike typical, they haven't copy-pasted the package drawings, but give you references to the document numbers you need, on page 29:
98ASH70029A and 98ASS23225W
« Last Edit: April 08, 2019, 09:00:15 pm by Siwastaja »
 
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Online Circlotron

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Re: LQFP32 & LQFP44 IPC land patterns needed
« Reply #4 on: April 09, 2019, 07:44:18 am »
Okay, thanks. No wonder I couldn’t find it! I do in fact have that data sheet though.

Edit -> had a look at that reference... it only has info on the package appearance and dimensions. No info on the pcb pad sizes and location. :-( Back to square 1.
« Last Edit: April 09, 2019, 10:08:13 am by Circlotron »
 

Offline trophosphere

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Re: LQFP32 & LQFP44 IPC land patterns needed
« Reply #5 on: April 09, 2019, 11:56:34 am »
Page 3/6 of both package information pdfs: LQFP32 and LQFP44.
 

Online TK

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Re: LQFP32 & LQFP44 IPC land patterns needed
« Reply #6 on: April 09, 2019, 12:00:31 pm »
Try snapeda.com if you need a footprint for Eagle, KiCAD, etc...

https://www.snapeda.com/home/
 

Offline Siwastaja

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Re: LQFP32 & LQFP44 IPC land patterns needed
« Reply #7 on: April 09, 2019, 04:21:20 pm »
Try snapeda.com if you need a footprint for Eagle, KiCAD, etc...

https://www.snapeda.com/home/

A word of warning: if you use footprints made by others, including the libraries that came with your CAD, double check very carefully against the datasheet. Every time. For every freaking footprint. Even for a SMD resistor.

Having an incorrectly made footprint in a poorly maintained library is super common. The risk is, in my experience, tens of percents, if not more, per footprint. I have had to rework boards because I thought that I could safely use the 1210 capacitor footprint that comes with Altium. And, based on what I see on the forums and like, I'd guestimate that a wrong footprint is #1 reason for respin for hobbyists.

The consequence is, if you use a proper CAD (which has to have good, quick to use drawing tools), finding, downloading, double checking and often modifying the existing footprint tends to take more time than drawing it from scratch (and then you get the layers as you want them). Which is one of the reasons that in a professional environment, everybody builds their own libraries ground up (or, use company-wide libraries built by a hopefully capable employee, who is a designer themselves - if the libraries don't work, the company will be in very deep shit very quickly!).

For some reason, 3D models you find online tend to be of better quality, and they are, if not lower risk, but lower consequence items (small errors don't automatically ruin your design in most cases; very rarely is the 3D shape so critical; and plainly wrong 3D model is caught by the eye by not matching the footprint - supposing the footprint is correct). Furthermore, making these models yourself is more time-consuming. And then, the 3D data formats are standardized and there is no problem importing it, and putting in on the layer you want to use for 3D bodies. So, I'm not suggesting against using random downloaded 3D models, especially in mechanically forgiving designs.
« Last Edit: April 09, 2019, 04:25:30 pm by Siwastaja »
 

Online Circlotron

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Re: LQFP32 & LQFP44 IPC land patterns needed
« Reply #8 on: April 10, 2019, 02:26:54 pm »
Okay, so I've made the footprints now.
Where should the reference point be, the centre of the part or pin 1?
 

Offline T3sl4co1l

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Re: LQFP32 & LQFP44 IPC land patterns needed
« Reply #9 on: April 10, 2019, 03:27:36 pm »
Center.

I mean, you can put it where you like, it's your design.  Center is most common though.  IPC-7351 section 7.3.1 p3 says: "Each surface mount device is aligned using the body center and a starting orientation for reference."

Tim
Seven Transistor Labs, LLC
Electronic design, from concept to prototype.
Bringing a project to life?  Send me a message!
 


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