Oh well. You would think somebody would make a cheap socket for them. I have managed to burn-out
two demo boards and it would be nice to just pop the chip out in put in another one.
It's not easy to burn out a board but if you are inclined to do so then certainly you would need a board with a standard 40-pin DIP surely as they are easy to socket. Anyway are you talking about QFN (no leads) or QFP (gull wing leads)?
I am thinking like the BOE board. Chances it is going to burned out? High. Replaceable chips in those things would
make the price of the board less scary.
I use DIPs in my projects but would be great to have a thru-hole socket for the space-saving smaller chips.
I used the stuff Leon keeps recommending, Chipquik. As promised, it makes removing ICs from a PCB much easier.
You mentioned you like the space-savings of the smaller chips. I use these little boards with the Prop. If you slice one of the smt pads on the back, you can add a SOIC EEPROM and really keep the size down.
I used the stuff Leon keeps recommending, Chipquik. As promised, it makes removing ICs from a PCB much easier.
You mentioned you like the space-savings of the smaller chips. I use these little boards with the Prop. If you slice one of the smt pads on the back, you can add a SOIC EEPROM and really keep the size down.
If the chip is fried then there is no point in trying to save it as it is far easier to push a sharp blade through the leads just where it meets the package so that you can remove the package with the pins still soldered to the pads. Then you blob on a generous amount of solder and run a hot iron along the pads scooping up all the pins in the resultant solder ball. This saves the pcb pads from undue stress and copper lifting.
BTW, the OP may have mistakenly refered to his chips as "QFN" rather than QFP.
I am thinking of just not myself. If a school wanted to get 40 of these education boards for the classroom. Soldering new chips in would
not be a selling point.
Just seems a design problem to send to a Chinese manufacturer if there isn't already a product out there.
I've never heard of sockets for QFN parts. There would be a problem with the large pad that they usually have on the underside.
Someone has to sell a test socket for QFN. How else would you test QFN chips after packaging? (ok it might cost $$$$...)
It also occurs to me that with an adapter PCB, you could fit a QFN or QFP part into a PLCC socket. (ok, it might only work with specific socket brands) The adapter would need castellated edge contacts just like what a lot of surface mount modules use.
A QFN adapter socket is around $84-100. No affordable at all, unless the hobbyist likes to burn money. Just get a schmart board and learn to solder QFP..
And a adapter like Lawson wants I'm sure can be fabricated but it will cost $$$$, since there is zero market for it. Commercial boards don't use PLCC adapters any more. Hobbyists just have get learn to work with SMT if they want to use the latest IC's.
Someone has to sell a test socket for QFN. How else would you test QFN chips after packaging? (ok it might cost $$$$...)
It also occurs to me that with an adapter PCB, you could fit a QFN or QFP part into a PLCC socket. (ok, it might only work with specific socket brands) The adapter would need castellated edge contacts just like what a lot of surface mount modules use.
Lawson
So you would still have a dud chip soldered to a pcb, even if that pcb were small, you are throwing this and the assembly costs away. I would really address why these chips are being fried in the first place and then do something about protecting it, whether it needs current limit resistors or isolation etc. BTW, I find simple 220 ohm resistors in each pin a simple means of protection as most pins are never required to sink or source more than perhaps 10ma so you can just connect these straight to LEDs, transistors, optos, etc. I have lots of designs and plug-in modules and despite the haphazard nature of some bread-boarding it has been extremely rare for me to fry a chip or two.
Ragtop
Posts: 406
Comments
is more the thing, they won't be cheap - used for programming chips, not mounting them.
two demo boards and it would be nice to just pop the chip out in put in another one.
Its pretty easy to cut a qfn chip off in the lab when its on one of these. But its $
make the price of the board less scary.
I use DIPs in my projects but would be great to have a thru-hole socket for the space-saving smaller chips.
I've burned out a few QFP chips myself.
I used the stuff Leon keeps recommending, Chipquik. As promised, it makes removing ICs from a PCB much easier.
You mentioned you like the space-savings of the smaller chips. I use these little boards with the Prop. If you slice one of the smt pads on the back, you can add a SOIC EEPROM and really keep the size down.
If the chip is fried then there is no point in trying to save it as it is far easier to push a sharp blade through the leads just where it meets the package so that you can remove the package with the pins still soldered to the pads. Then you blob on a generous amount of solder and run a hot iron along the pads scooping up all the pins in the resultant solder ball. This saves the pcb pads from undue stress and copper lifting.
BTW, the OP may have mistakenly refered to his chips as "QFN" rather than QFP.
not be a selling point.
Just seems a design problem to send to a Chinese manufacturer if there isn't already a product out there.
Someone has to sell a test socket for QFN. How else would you test QFN chips after packaging? (ok it might cost $$$$...)
It also occurs to me that with an adapter PCB, you could fit a QFN or QFP part into a PLCC socket. (ok, it might only work with specific socket brands) The adapter would need castellated edge contacts just like what a lot of surface mount modules use.
Lawson
And a adapter like Lawson wants I'm sure can be fabricated but it will cost $$$$, since there is zero market for it. Commercial boards don't use PLCC adapters any more. Hobbyists just have get learn to work with SMT if they want to use the latest IC's.
So you would still have a dud chip soldered to a pcb, even if that pcb were small, you are throwing this and the assembly costs away. I would really address why these chips are being fried in the first place and then do something about protecting it, whether it needs current limit resistors or isolation etc. BTW, I find simple 220 ohm resistors in each pin a simple means of protection as most pins are never required to sink or source more than perhaps 10ma so you can just connect these straight to LEDs, transistors, optos, etc. I have lots of designs and plug-in modules and despite the haphazard nature of some bread-boarding it has been extremely rare for me to fry a chip or two.