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Boardwalk :: Forum List Luminary Micro Forums Design Stellaris 2006
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achoox4

Senior Boarder

2006/11/21 15:53

QFP pin pitch?

What is the pin center spacing of the QFP?

I'm still trying to work up the courage to order an '811 (as oppposed to a relatively easy .05" 101) to make my first non-evalboard prototype.

(The package diagram seems to indicate 0.5mm, but the dimension labeling is a bit blurry (the labels for the center spacing and the 0.50 value in the table are 2 different-shaped blobs), and my rough measurements across multiple pins come out closer to 0.4mm.)

Post edited by: achoox4, at: 2006/11/21 16:03

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LMI Eric

Moderator

2006/11/21 16:27

Re:QFP pin pitch?

The center spacing of the pins is 0.5mm.

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verminsky

Junior Boarder

2006/11/21 18:16

Re:QFP pin pitch?

Don't be afraid of the QFP 0.5mm pitch. I used to be, but have found that they're actually pretty easy to hand solder.
If you use a locking tweezer type tool to hold the part in place and check the alignment with a decent magnifier, you just need to paint some liquid flux over the pins and apply a bead of solder with a small tip, low wattage iron - allowing it to short across many pins if necessary. Then press some some miniature solder wick between your iron and the pins, and it miraculously cleans right up. As long as you take care not to overheat the chip, and really inspect it well after soldering to make sure there are no hairline shorts, all you need is some MEK or even rubbing alcohol and a rag to clean off the excess flux. I have found this method to be essentially foolproof - and I'm just an old fool, with poor eyesight and shakey hands!!

Good luck.

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achoox4

Senior Boarder

2006/11/22 10:38

Re:QFP pin pitch?

Thank you.

As far as the soldering is concerned, my biggest problem is finding/making a usable PCB, rather than soldering once I have a PCB.

I just realized that the Parallax SX48 uses the same package, and they make a $10 protoboard. VSS and VDD are in different locations, but since it also has the SX52 footprint on it, there ought to be enough room to cut and reconnect traces.
I have a few of the rare SX52 version of this packed away; I'm not about to unsoldere the SX52 from one of these, but I can se whether this may be workable.
On the other hand, a SchmartBoard fitting the 48 pin .5mm QFP costs $5 for a flat board or $10 for a version with trenches for the pins, but then you don't get the proto area and (5V) power supply parts.

Either way, it all looks easier already.

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verminsky

Junior Boarder

2006/11/22 11:11

Re:QFP pin pitch?

You might try these guys - Their 48 pint QFP to DIP is only 0.7" wide which allows one to plug it into a solderless breadboard with enough room to fit wires on both sides-works well - around $8.00 each. The only drawback is that pin 1 of the dip is NOT pin 1 of the QFP. I did find ones that are pin for pin compatible (using 2 sided pcb DIP adapter) but they were expensive.

jc

Accutek Micro


http://www.accutekmicro.com/pdf/48%5F56%5FPin%5FDip%5FAdapters%2Epdf

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achoox4

Senior Boarder

2006/11/22 12:41

Re:QFP pin pitch?

Thanks. Usually, all the adapters I can find are either too expensive or a larger pitch.
This company is just a few minutes from my daily commute. That'll certainly save on shipping.

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