6
votes
Purpose of pins on side edge of QFN package
When the die was attached to the leadframe and the epoxy encapsulant was molded over it, the leadframe was still connected to a larger structure (and probably to an array of other die locations).
...
- 134k
6
votes
In production, is there a significant difference between QFN or TQFP components other than space?
For anyone reading this down the line, there is one other major issue not yet mentioned regarding QFN vs QFP when it comes to commercial production of boards - and that is reliability.
If you have a ...
6
votes
Accepted
Will PCB board house accept this QFN thermal pad via design (KiCad)?
they are pads which connect from front copper layer to bottom ground layer
You've just described a via.
Do you think the board house will accept this?
If they're on the ball they won't accept it....
- 47.1k
6
votes
What does 32 mean in QFN 32? Term is related to IC chip specification
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 ...
- 7,705
6
votes
Help is needed with IC identification
I found the schematics here by searching for your P5WE0 Schematic, landing here, then checking Rev 2.0. Then I Ctrl+F searched the PDF for PU6 since that appears to be the part designator labeled on ...
- 22.9k
5
votes
Accepted
Why do I have shorts/bridges on QFN packages on PCBA during assembly? Stencil Printing problem
Solution:
I borrowed a new stencil printer and improved the process and I got proper results. I didnt need to change the stencil. Thank you for the tips.
These things must be done in my case:
Wipe/...
- 453
5
votes
Accepted
VQFN Footprint for PCB Design?
You do not know how to use a PCB design tool unless you know how to make a part for yourself — what you own owns you, self-sufficiency, and all that jazz.
Reference
You should always be familiar ...
- 689
4
votes
Accepted
How to Solder TQFN packages that are on both sides of the PCB
There are a few ways to do this:
1) Direct the heat flow on the PCB
There are a few ways to direct the heat flow, you'll have to get creative especially if the parts are near each other. You could ...
- 88.8k
4
votes
Remove/exclude exposed pad of QFN package from PCB layout
My conclusion upfront: It's not worth considering going your route, the potential downsides outweigh the fact that you might get a more compact layout.
Generally, you'd have to triple-check that your ...
- 100k
4
votes
Unusual IC package in Li-po charging circuit
From the application, I'm betting it is or incorporates a current sensor with the sense pads completely underneath the package like so:
Photo is a Si8512 from Digikey.
- 23.1k
3
votes
Question about traces on a QFN24
I would be more concerned about crosstalk of differential signals being unbalanced or following different paths rather than following the same path on opposing layers, and noise decoupling on Vdd/Vss ...
- 148k
3
votes
Accepted
LGA parts and hot air soldering
First of all, if you are using lead-free solder, it sucks, if possible use leaded solder.
There are two categories of soldering. With interaction and without. Interaction refers to the necessity of ...
- 7,261
3
votes
In production, is there a significant difference between QFN or TQFP components other than space?
Unless you need the heatsinking effect of the large middle ground pad, you may find the QFP easier to lay out the PCB for. A QFP provides room under the chip to put vias, possibly making fan-out ...
- 31
2
votes
Accepted
Solder Mask Expansion Rules and Passive design in Altium
Use the IPC wizard to design the footprints from the device dimensions and tolerances. QFN and discretes are definitely covered, DFN may not be, at least in older versions.
You should take into ...
2
votes
Accepted
Do all ATmega32u4 QFN ground pads need to be connected?
Having multiple GND pins serves several purposes:
Lower ground inductance. In this case, the pins will be internally connected, and not connecting one to GND will worsen performance, but it could ...
- 81.8k
2
votes
Accepted
How can I align chips on PCB?
There are two stages, the initial alignment, and then keeping alignment during soldering.
Machines are necessary for volume runs, but for prototypes a microscope will suffice for initial alignment. ...
- 174k
2
votes
Accepted
Small DFN chips come out twisted from the oven
This is most likely caused by the long exposed pads.
In the oven, all the paste doesn't melt at the same time. Those long pads that flow first have an enormous amount of surface tension and can pull ...
- 9,504
2
votes
How do i solder qfn package using soldering iron?
I normally put some solder paste on the pads, place the QFN on the board, and reflow with hot air. With some trial and error you learn how much solder paste to put, but you really need quite little.
...
- 2,827
2
votes
Accepted
Removing QFN Lead Frame From PCB
The lead frame is basically just a solid chunk of copper, and in the process of trying to desolder it, I ended up just tinning the copper slug.
It dawned upon me that as it is copper an a decent heat ...
- 70.7k
2
votes
Removing QFN Lead Frame From PCB
You'll need a h*ll of a lot of heat to get that solder to melt, that's by design, all those vias and probably 2oz or greater copper thickness is designed to spread the heat.
An air gun probably isn'...
2
votes
When should bare die be used instead of QFN/BGA packages?
Asking pros and cons of Bare dice vs packaged parts is like asking the pros and cons of buying a house versus flying an airplane... The circumstances where a bare die is appropriate are very different ...
- 15.1k
2
votes
What's going wrong with my solder paste / mask?
It looks like the ratio flux/alloy is much too high, but I don't think it's a problem with the paste itself. Flux and alloy balls tend to separate from each other due to their different density. ...
- 2,923
2
votes
What are best practices for QFN footprint design for manufacturability?
Many of the resources I can find say that using paste over the entire thermal pad is too much solder, and will raise the part off the board enough to prevent the pins from reflowing properly. But is ...
- 3,456
1
vote
Accepted
Thermal pad with a via: how to deal with solder paste?
You can use a pastemask checkerboard pattern to apply paste on the square, with the pattern covering your via in the middle. Then you shouldn't have a problem with wicking into the via as long as it's ...
- 58.4k
1
vote
Accepted
QFN Programming / Tester / Adapter
What you are looking for is called a QFN ZIF (zero insertion force) socket.
(A few manufacturers include Aprilog and Test sockets, but they only have square pined QFN ZIF sockets listed). It's likely ...
- 88.8k
1
vote
Question about traces on a QFN24
Pin 18 is fine but I don't see bypass caps on the supply lines close to the chip.
I assume you're using an external oscillator rather than a crystal- the XTAL1 pin routing is also sensitive.
1
vote
Accepted
Question about traces on a QFN24
This is perfectly fine. Since there's solder mask on top of that trace, you won't get any problems when soldering the chip. Of course, if you want to make it nicer, you can - but there's no technical ...
- 20.5k
1
vote
SMT soldering for QFN package without legs
The usual way is solder paste (mixture of tiny balls of solder and flux) and a reflow oven. The paste can be applied using a syringe or by speading the paste over the board using a stencil.
For small ...
- 73.6k
1
vote
Accepted
Pros and Cons of QFN and BGA packages
Beside what is already said in comments,
BGA has the disadvantage, its hard to replace the IC by hand (but possible)
Advantage is, HF Signals like High speed busses can be guided directly from under ...
- 2,666
1
vote
What does 32 mean in QFN 32? Term is related to IC chip specification
32 is the number of pins on the package. QFN32 is a QFN (Quad Flat No Leads) package with 32 pins.
See here
- 1,213
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