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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 package is of course smaller, but I have enough space on the board, so that is not an issue.

For prototypes, the TQFP is easier to handle because I could even hand-solder them, if a reflow oven and stencil is not available. But for automated production, this should't matter, or does it?

For instance: would a PCB manufacturer recommend to use QFN because they are easier to handle by the pick-and-place machines, resulting in a price cut?

The difference in component price appears to be small, too.

Niels Heidenreich
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4 Answers4

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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 product that deals with lots of thermal cycling or other vibrational/mechanical stress, leaded parts are the way to go. Leadless parts look neater, but don't always take up less space since there's usually a big thermal pad that you can't route signals through. If you're going to produce a thousand boards that will see a rough life (outdoors, automotive, etc), leaded parts generally last about 10x longer than leadless parts before you start to see issues with cracking solder joints, etc.

I work as a EE in oil and gas, formerly aerospace, and I swear against leadless parts in these applications for this reason.

Of course, you can always take additional measures to help even the playing field (primarily potting your leadless ICs), but this doesn't guarantee that you're giving your parts the same longevity as a leaded part. Additionally, this will typically make your leadless implementations more expensive due to the additional manufacturing steps required.

George Sullivan
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  • Things have moved on with the QFN as manufacturers learnt the weaknesses and it comes downto the internal leadframe. These poor packages were weeded out quite quickly soxuh so that QFNs are extremely reliable in high vibration and temperature environment. There was a multi-year analysis of this done not too long ago, I will try to find the links –  Aug 20 '20 at 15:48
  • That's good to know @JonRB. I'd be very interested in reading those links! – George Sullivan Aug 20 '20 at 17:11
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I recommend QFN. why?

  • smaller, cheaper in mass production.
  • it requires less solder ( because of small pins ) and therefore monetary efficient.
  • it is soldered faster than TQFP ( using an soldering machine like that pick and place that uses solder paste and hot air) because QFT packages stick to pad because of their GND tab.
  • The board will look niftier and neater :) and also more professional.
AHB
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    Given the option I always choose QFN or DFN over any other package because I find it easier to solder (reflow) and yes it looks so much more "nifty" :) – Majenko Dec 09 '15 at 13:15
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    With QFN devices, be careful of the solder screen aperture at the exposed pad: too large and the device will 'float' on the exposed pad, and most likely partially tombstone the part leaving some contacts in air (and not on pads). A 50% aperture is usually used, although TI recommends dotting. – Peter Smith Dec 09 '15 at 13:26
  • @Majenko Welcome back! good to see you here again. – Roh Dec 09 '15 at 16:38
  • IMO some parts of this answer are incorrect. – Roh Dec 09 '15 at 16:39
  • @Roh Thanks :) I've been spending all my time over on Arduino.SE helping the Ardueenies over there... – Majenko Dec 09 '15 at 16:39
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The BlueSky's answer isn't completely correct.

  • Price: There isn't big differnce or maybe it's better to say there is no differenc. e.g. check out ATMEGA8A-MU and ATMEGA8A-AU.
  • Size: Again There is no big differnce indeed. in many cases QFN is half of TQFP but this factor doesn't decrease the price of manufacturing so much. although it makes your PCB a bit compact.
  • Solder and Soldering: IMO solder consumption wouldn't be significant and most probably there wouldn't be any difference in soldering QFN and TQFP. because I'm sure they just put components on PCB and soldering paste on pads.

NOW I'm sure you are asking yourself "then What's the difference between these two packages? well the big differences are in electrical characteristics. for example QFN has smaller leg's length than TQFP and this means low capacitance and in some cases it's so important. many RF ICs use these kind of packages. or QFN packages include an exposed thermal pad to improve heat transfer out of the IC (into the PCB).

Roh
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    Size, price and the solder amount IS noticeable at mass production. as he said. although it does not affect the price much, but there is difference (though small). And you are right with electrical benefits. – AHB Dec 09 '15 at 16:42
  • @BlueSky He said "significant difference" then definitely it's not as you are saying. is it? :) – Roh Dec 09 '15 at 16:47
  • ok. but he also said he wants 1000 boards. then it gets significant. – AHB Dec 09 '15 at 16:49
  • @BlueSky How many? 5 bucks? 10 bucks? – Roh Dec 09 '15 at 16:51
  • yes :). I know it is small. and I said you are right. but I am not wrong. – AHB Dec 09 '15 at 17:00
  • @BlueSky In some cases you are. :) – Roh Dec 09 '15 at 17:04
  • For an ATMEGA328 at Farnell, the cheapest in QFN is 1,47 € for 100 pc.; the cheapest for TQFP is 1,86 €. So assuming that scales about proportionally to 1000 pc, that would make a difference of 390 €. That’s significant money. But I have no idea how representative this is. – Niels Heidenreich Dec 10 '15 at 17:21
  • @NielsHeidenreich link? – Roh Dec 11 '15 at 04:16
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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 easier.

Stephen Makk
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