help with whole board desoldering

So I've found a toaster oven with an element on top and bottom and started to get crackin at the junk boards I've scavenged over time, I've done 4 so far and gotten tons of pushbuttons, ics, fets, caps and processors, however I usually only get 85% of what's on the board and I was wondering if there's a better method that still uses the toaster ovwn and not a desoldering pump
right now I have a tinfoil sheet in there so the plastic doesn't screw up the bars, (don't get very many connectors maybe 5 good ones out of 25), and I put a small blob of solder paste in the center of the board, when the paste melts I wait another 30 seconds and basically grab it with paper towels and bash it on a cardboard box edge and the components fall in effortlessly
I've burnt my finger a few times because its hard to grab the board with paper towels, anyone use something better that's supportivw enough for like whole motherboards?
also I can't seem to get the smaller stuff off the board like 0805 and smaller components(very few come off)
Also are the capacitors still good after this intense heat? The plastic wrap usually just starts to melt, but if I don't have a short and my meter says its still accurate capacitance its still useful right?
I haven't tried any but would the general ics and fets be good still? I imagine they are just hot enough for the solder to melt, idk what temperature that is but I believe its less than 400F?
Any thoughts?

winner10920:
I've burnt my finger a few times because its hard to grab the board with paper towels ...

Try oven mitts?

Lol couldn't find a pair in the house
also how do I find out what all the smaller ics are?I imagine 3 pin stuff is transistors or mosfets but there's some 5 pin too
They have 4 numbers/digits but google reveals nothing

winner10920:
Lol couldn't find a pair in the house
also how do I find out what all the smaller ics are?I imagine 3 pin stuff is transistors or mosfets but there's some 5 pin too
They have 4 numbers/digits but google reveals nothing

There is no magic answer. Your helps if you can deduce how the part is being used. That'll give you some idea of where to start.

Darn, its all desoldered and its from a dvr, pretty new, got traces that you need a magnifying glass to see, following it thru the pinhole vias would be very hard, especially with the many differnt ics, all very small with many closely spaced pins in all kinds of packages, some of the soic seem useful like an octal dtype flip flop I saw and some other simple stuff, but ones like sdram ics are pretty hard to figure out what to do with and follow
I was hoping for some useful transistors/fets, is there a safe way to test an unkown chip to see if its a npn/nchan or pnp/pchan?

winner10920:
So I’ve found a toaster oven with an element on top and bottom and started to get crackin at the junk boards I’ve scavenged over time, I’ve done 4 so far and gotten tons of pushbuttons, ics, fets, caps and processors, however I usually only get 85% of what’s on the board and I was wondering if there’s a better method that still uses the toaster ovwn and not a desoldering pump

You could try a hot air/heat gun…

winner10920:
right now I have a tinfoil sheet in there so the plastic doesn’t screw up the bars, (don’t get very many connectors maybe 5 good ones out of 25), and I put a small blob of solder paste in the center of the board, when the paste melts I wait another 30 seconds and basically grab it with paper towels and bash it on a cardboard box edge and the components fall in effortlessly
I’ve burnt my finger a few times because its hard to grab the board with paper towels, anyone use something better that’s supportivw enough for like whole motherboards?

Get a pair of “Ove-Gloves”:

http://www.asseenontvguys.com/anti-steam-ove-glove.aspx

(Note - you can find them cheaper than this; this is only for informational purposes - plus that is for -one- glove)

The nice thing about them is that they are more flexible and easier to use than oven mitts.

winner10920:
also I can’t seem to get the smaller stuff off the board like 0805 and smaller components(very few come off)
Also are the capacitors still good after this intense heat? The plastic wrap usually just starts to melt, but if I don’t have a short and my meter says its still accurate capacitance its still useful right?

You are probably wasting your time and energy for nearly any non-IC surface mount components (and even for a few of the IC surface mount components). Most electronic components can be bought new on Ebay (and sometimes surplus) for very little money (and as long as this is for hobby purposes, you don’t have to worry about supply issues). I definitely wouldn’t bother with capacitors, they are simply not worth it.

winner10920:
I haven’t tried any but would the general ics and fets be good still? I imagine they are just hot enough for the solder to melt, idk what temperature that is but I believe its less than 400F?

Those and most SMT components should be OK; they go thru essentially the same process for soldering them on a board. There is an upper limit for temperature (for a certain time duration), but I doubt your technique hits it. You might want to look at some of the spec sheets for SMT components (many sheets will give a soldering “reflow” curve for the component in question).

winner10920:
I was hoping for some useful transistors/fets, is there a safe way to test an unkown chip to see if its a npn/nchan or pnp/pchan?

This will do it for transistors/diodes:

http://www.peakelec.co.uk/acatalog/jz_dca55.html

But that gives the general characteristics (eg. PNP/NPN, MOSFET etc.) not the exact part number. Also for the price you could buy a lot of transistors.

+1 for ove-gloves, they rock

but for the price mentioned in the link above you could buy 117 brand new BSS84 P channel fets on a strip of tape, so its really up to you (though I would get a pair of ove-gloves anyway, thats how much they rock)

ps: for 2 lead chip packages like 805 resistors, they take no time at all to saturate with heat so the solder on the other end becomes plastic, pick a end, heat it up and try to flip them up using your iron, they pop loose in no time on one side with a standard iron

I've had better success with 'slapping' the components off a board rather than trying to pull them off. While the board is hot and the solder in a liquid state, grab the board and smack the opposite edge from where you are holding sharply and with force against a flat surface such as a table top or the floor. Many components will fly from the board. - Scotty

Thats wat i do just grab and bang lol
I did find a whole lot more small smd stuff in the cracks of the box, still a lot left on the board tho
How hot can stuff handle like this?

Many circuits have the components glued on the underside so that they don't come off when the top side is done or when it goes over the solder wave.

That might explain it a bit, one board 90% came off but another similiar sized board from some other company maybe 40% fell off at the same technique
so far one other problem is the heating elements warm thenback faster so any plastic connectors tend to distort In the back, and the front doesn't get hot enough to pop off by then
do you think its better to heat from both sides or just the top?

do you think its better to heat from both sides or just the top?

I think you are better using a hot air gun to remove the plastic components first. Also remove the through hole components.
Then when you have stripped off the good stuff I would apply heat only to the side you want to unsolder. However some boards do not use thermal relief on ground plane pads and that will not help getting stuff off.

If grabbing the board is the problem, I have used these tweezers which are in the normally closed position. Usually tweezers are normally open and when you squeeze them you can grab stuff, and when you let go the springy effect brings it back to the open position. The normally closed tweezers help me to grab stuff and lock down into them. I got them from Fry's Electronics.

I still haven't gotten a better method for grabbing the board, probably gonna buy a mit or glove
I did find a way to get all those light small smd stuff of, a strong magnet on a metal rod I stick in the oven when its hot enough and it just picks up all the stuff, then I just brush it off
so far its been a great experience, Im using the blank boards and all the components to practice hand soldering the many pin smd ics of all kinds of packages, unofrtunetly I can't tell if I burn a chip but atleast I can see if it looks good and has continuity