ESP8285 IC QFN32 is a chip.
https://robu.in/product/esp8285-ic-qfn32-original/
What does 32 mean in QFN 32? If I have a part/ footprint having the name as QFN50P500X500X90-33N-D. Will it be different than QFN 32 ?
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asked Aug 27, 2020 at 12:00
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\$\begingroup\$ This is very fundamental stuff. Pretty much all IC packages no matter type have a number specifying the number of pins. It's been like that since the DIP days. \$\endgroup\$– LundinCommented Aug 27, 2020 at 14:23
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5 Answers
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What does 32 mean in QFN 32?
It means 32 "pins" or connnection points around the edge. OK, so a QFN package doesn't have pins - it has solder connections. There are 32 of them on the edges of the chip.
If I have a part/ footprint having the name as QFN50P500X500X90-33N-D. Will it be different than QFN 32 ?
No. Not unless your layout system is being very, very confusing. A QFN50 package has a 5 mm x 10 mm body, while a QFN32 package has a 5 mm x 5 mm body. So labelling a footprint for a QFN32 part with a starting field of "QFN50" would be an appalling way for the footprints to be identified.
answered Aug 27, 2020 at 12:34
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\$\begingroup\$ Thanks. I decided to choose a different foorprint:
QFN-32-1EP_5x5mm_P0.5mm_EP3.45x3.45mm. I need a 5mm x 5mm footprint. A small follow-up question please: From the name I guess the pitch is 0.5 mm? and whats that 3.45x3.45 stands for? \$\endgroup\$ Commented Aug 27, 2020 at 12:40 -
\$\begingroup\$ @NeedSomeLuck - 3.45x3.45 is the size of the exposed pad under the IC. \$\endgroup\$ Commented Aug 27, 2020 at 13:11
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\$\begingroup\$ @WhatRoughBeast it is not craaaaazy to have footprints named for part number, it is confusing for sure, but some organizations decide to go that strict. To your point, in the cases when I need to support a strange mfg recommendation or other weirdness like controlling stencil dimensions/solder paste for a specific part, i still include the generic name for the footprint in front
QFN32-PARTNUMBER\$\endgroup\$– crasicCommented Aug 27, 2020 at 15:36
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Lets break the footprint name to its parts:
- QFN - Quad, flat, no lead.
- 50P - 0.5mm pitch.
- 500X500X90 - 5mm by 5mm by 0.9mm
- 33 - 33 pads, one of them is the bottom pad.
- N - This usually means nominal footprint.
- D - Variant, this is a manufacturer specific version of this package.
This naming convention is specified in an IPC Standard (I don't remember which one).
answered Aug 27, 2020 at 15:31
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32 is the number of pins on the package. QFN32 is a QFN (Quad Flat No Leads) package with 32 pins. See here
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This is just the amount of pins on the IC. QFN32 will have 32 pins on the IC
Looking at the picture in your link:
You can see that there are 32 pins, hence the '32' after QFN. You will also notice the large pad in the center. Not all packages have this extra thermal pad, so always check the footprint on an IC before creating one in your preferred PCB design package. This thermal pad will usually have to be created as pin no. 33
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\$\begingroup\$ Incorrect. This is a 32 pin footprint, look it up and you'll find that clear. \$\endgroup\$ Commented Aug 27, 2020 at 12:10
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\$\begingroup\$ @ChrisStratton Just googled the part number. You are correct. Removed the incorrect information. Thanks for the heads up. I think the 50 after the QFN is a bit misleading there! \$\endgroup\$– MCGCommented Aug 27, 2020 at 12:16
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\$\begingroup\$ Thanks. Ys the '50' was confusing. I decided to choose a different foorprint:
QFN-32-1EP_5x5mm_P0.5mm_EP3.45x3.45mm. I need a 5mm x 5mm footprint. A small follow-up question please: From the name I guess the pitch is 0.5 mm? and whats that 3.45x3.45 stands for? \$\endgroup\$ Commented Aug 27, 2020 at 12:41 -
\$\begingroup\$ @NeedSomeLuck seems I checked the responses a little too late, your follow up has already been answered above \$\endgroup\$– MCGCommented Aug 27, 2020 at 14:10
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32 is the number of perimeter pins.
Some parts may have a central ground or thermal pad, radio parts as you link especially. Where that needs to be electrically connected it becomes logically a "pin" too, and if particular PCB software cannot handle pin numbers that are not purely numeric, it would be pin 33.
answered Aug 27, 2020 at 12:06