Questions tagged [qfn]

For questions related to the QFN (quad-flat no-leads) component package.

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Can I make GND vias like this under my QFN package?

Can I make GND vias like this under my QFN package?
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What's going wrong with my solder paste / mask?

A short question this - I've got a board with a QFN-32 0.4mm pitch footprint, I ordered this stencil, and a tube of this solder paste, and the result is in the picture below. Now, I'm new to this, but ...
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Help identifying an unknown IC

I work in a fablab and I'm sorting through our electronic components, but here I stumbled upon a component with just too few information... It's a QFN package and I don't have anything else to work on....
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Thermal pad with a via: how to deal with solder paste?

I have a TLC59283RGET part which comes in a VQFN24 housing. It has a thermal pad on the bottom. In my schematic, I have placed a via on that thermal pad, so I can route it as GND to other places. I am ...
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QFN Programming / Tester / Adapter

I need to be able to test a batch of components ordered abroad. Soldering and removing them one by one would take a long time. I need to be able to read this 6 by 4 component. But can't find anything ...
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6 votes
1 answer
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Why do I have shorts/bridges on QFN packages on PCBA during assembly? Stencil Printing problem

I am trying to do a home assembly of PCB but I have issues after reflow soldering. Especially I have bridges/shorts on the pins of QFN packages. I have assembled multiple boards other joins are okay ...
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How do I calculate the x & y dimensions of pin 1 for a QFN package?

I'm trying to make changes in pad location. How do I calculate the x & y location of pin 1? Is there any mathematical calculation, how do I do those calculations? I'm sharing an image of a QFN ...
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3 answers
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Question about traces on a QFN24

On my board I have an LAN8720AI QFN24 package. When I route it via FreeRouting I get this: As you can see most pins are routed fine but some like pin 18 (RMII_TXD1) just goes straight up instead of ...
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SMT soldering for QFN package without legs

I have soldered through-hole and SMT before but this is the first time I have to do SMT (QFN) package which has no legs. I tried the traditional approach, Flux, solder, then heating the component. But ...
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2 votes
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448 views

When should bare die be used instead of QFN/BGA packages?

I have no experience with bare die as a package, and I have been recently tasked with deciding between bare die, BGA, or QFN package for a SoC. Searching the internet, I have not really found much ...
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909 views

Pros and Cons of QFN and BGA packages

As a PCB designer, is there a known list of advantages and disadvantages to using BGA vs. QFN packages? Here is the list I have discovered (please correct me if they are incorrect): BGA Pros: Smaller ...
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What does 32 mean in QFN 32? Term is related to IC chip specification

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 ...
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Solder QFN88 by Hand

I just received my newest board i've designed and wanted to solder the first prototype. One of my Chips has a QFN88 Footprint. I'm quite experienced, but i just couldn't do it. Because of the small ...
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417 views

Remove/exclude exposed pad of QFN package from PCB layout

I am doing a PCB layout with a Atmel/Microchip MCU ATSAML21E18B-MUT‎ which has QFN-32 package 5x5 mm. This board can have a maximum of 20x40 mm and I am having problems with space because the circuit ...
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Will PCB board house accept this QFN thermal pad via design (KiCad)?

I am going to be ordering this board from JLCPCB which has some 0.2 mm hole diameter thermal vias on a QFN pad, and it says on their capabilities page that the smallest via hole size is 0.3 mm, BUT ...
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Small DFN chips come out twisted from the oven

This is a 2 x 2 mm chip with 12 no lead contact points. Half of the time I get it out of the reflow oven, it's twisted like in the image below. I am using a stencil in order to lay the paste down and ...
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How do i solder qfn package using soldering iron?

I don't have any soldering station but I need to solder the qfn package chip so how I solder it using a normal soldering iron.
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LGA parts and hot air soldering

Does the solder pattern on these huge pads indicate what might be going on ? The parts would not work about 80% - 90% of the time. I am trying to follow the ramp_up-soak-reflow-ramp_down curve to ...
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PCB design - paste coverage calculation for exposed pad (TL;DR version?)

I have created a Web tool for creating solder mask and paste mask for exposed pad: https://jsfiddle.net/d1wang/5t6urzwo/ The idea is get around limitation of DipTrace and help automate footprint ...
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Soldering 0.4mm pitch QFN 48 chip

I have this QFN 48 chip which has the following design : As it can be observed, the pitch is 0.4mm. It seems like the conventional QFN adapters won't fit because the conventional ones has the pitch ...
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Removing QFN Lead Frame From PCB

We have some PCBs that were designed to drive high-power ultrasound transducers. There was an issue with the boards early on that resulted in several of them blowing diodes. I have since fixed the ...
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1 vote
1 answer
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How to Solder TQFN packages that are on both sides of the PCB

Due to a careless selection of components (and you could say also bad layout) I ended up having a PCB with surface mount pads on both sides and on the same x,y coordinates. I have already used my ...
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How can I align chips on PCB?

I am searching for a method/device for aligning chips with pins/pads underneath, like QFN, LGA, BGA and others. I've been searching the Internet, but I could find anything except expensive (several k€)...
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Identify Quad Flat package

I looked for days trying to find datasheet to this component. I concluded that this is a Quad Flat No-lead. But trying to search the marking code gets me nowhere. I did however find couple websites ...
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QFN20 package sizes

I'm trying to use the capacitative touch chip CPT112S for a project. It comes in QFN20 3x3 package size but the pad layout is different to what I expected and so doesn't fit the DIP adapters I have. I'...
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1 vote
1 answer
572 views

Do all ATmega32u4 QFN ground pads need to be connected?

A QFN chip I'm working with (atmega32u4) has multiple pads connected to ground, see the picture. Is it really necessary to connect all these pads? Could I say omit one or is it really bad practice? ...
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1 answer
220 views

QFN32 exposed pad stencil

I made a pcb with a QFN32 with exposed pad but I feel like I've made a mistake on the stencil, in the exposed pad area. I managed to solder it and the chip (CC1310) is programmed successfully but I'm ...
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1 answer
782 views

VQFN Footprint for PCB Design?

I am currently working with TI's TPS61235. I need to put this IC onto a custom PCB for a project, but I cannot find any libraries for PCB designing software for this VQFN-9 layout. Is there anywhere ...
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4 votes
1 answer
708 views

Purpose of pins on side edge of QFN package

I have a QFN part that contains exposed pins on the side (in addition to the bottom). It looks like the quantity and spacing of the side pins are perfectly matched with the bottom pins, except there ...
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1 vote
1 answer
963 views

Questions about Solder Mask Expansion Rules and Passive design in Altium

I am working on my first Systems project as a student and I am learning how to integrate chips as I go along in Altium. I recently came across this question in which you provided a rule for ...
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Footprint of L6226Q

The L6226Q H bridge is using a QFN32 package. Actually in the datasheet, it has this layout: and it was noted that the pins 2 to 8 are connected to the die PAD and the die PAD must be connected to ...
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Removing QFN vias

I've used the footprint wizard to generate QFN package, the result: My question is, if it's OK to remove the vias since I want to put some components to save same room?
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4 votes
3 answers
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What are QFN sockets for?

I would like to use a QFN chip but soldering it is difficult as the required tools are unavailable. After searching online, I found that there are sockets available that provide pins for those chips, ...
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6 votes
3 answers
2k views

How bad is it to places vias under a QFN thermal pad?

I'm working on a PCB which has to be very small. There is a QFN IC which has a big thermal pad, although it doesn't really need to dissipate that much heat. So to save some space, I came up with the ...
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7 votes
4 answers
11k views

In production, is there a significant difference between QFN or TQFP components other than space?

When producing a run of PCBs, does it matter if I choose QFN or TQFP components? Say, I want to have 1000 boards manufactured with an Atmel AVR that is available in QFN or TQFP packages. The QFN ...
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4 votes
3 answers
3k views

QFN Standoff (Solder Joint) Height

When designing a QFN footprint, I've read from (reputation limited, only 2) sources... http://www.freescale.com/files/analog/doc/app_note/AN1902.pdf http://www.atmel.com/images/doc8583.pdf ...that ...
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5 votes
2 answers
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Potential pitfalls/caveats for developing a stencil for solder reflow

I'm developing a project that requires ICs that are in a QFN package, some have a slug on the bottom of the IC. Since these are QFNs, I'm not interested in hand soldering these; so I'm leaning toward ...
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7 votes
4 answers
10k views

How do I solder this tiny QFN chip

I am not very experienced with soldering. I have a basic soldering iron with a new tip, and a third hand. Last time I tried soldering wires to a ble chip that looked like this, I ruined two chips in ...
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5 votes
2 answers
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What does WFQFN stand for?

I saw this as a package type for an attiny microcontroller in the digikey catalog. I'm pretty sure that "QFN" stands for Quad Flat No leads. However, I'm not sure what prefixed "WF" means. Is there a ...
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4 votes
1 answer
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How to solder QFN-16 with a central pad component to proto-board?

I have a QFN16 breadboard adapter and an ASXL335 chip, which I'd like to solder to it: However, the accelerometer chip has a central pad, while board does not. This causes an annoying problem of ...
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16 votes
4 answers
654 views

If there are different packages for the same component, which one you should consider?

I am designing a small PCB for mass production, and I am trying to keep costs low. One of the components is available in several different packages: 24QFN, 32QFN and LP (TSSOP 24 Pin). There is a ...
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4 votes
2 answers
3k views

24-pad, 0.5mm pitch: better to use QFN or BGA?

For a certain TI component, I'm choosing between these two packages, both of which are 24-pad and 0.5mm pitch: QFN: http://www.ti.com/lit/ml/mpqf167b/mpqf167b.pdf (4 x 4 mm) BGA: http://www.ti.com/...
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8 votes
2 answers
3k views

Do QFNs really need that thermal pad?

Often a chip will be available in several different packages. Sometimes QFN which has a thermal pad, and TQFP which has no thermal pad. The justification for the thermal pad is that it helps conduct ...
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