how to remove dip chip perfectly?

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nixjoe
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how to remove dip chip perfectly?

Post by nixjoe » Fri Oct 18, 2019 11:52 pm

I'm used all method i can googled. but i don't want to damage the pin.
so I majorly use heatgun to blow the chip off. the result is lots "nowaday" pcb burn to black and old nintendo pcbs usually pop up big bubble after removing the chip.

Ice Man
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Re: how to remove dip chip perfectly?

Post by Ice Man » Sat Oct 19, 2019 1:02 am

Desoldering Pump is best for DIP imo.
Hot Air Station is recommended for SMD.

Heat Gun I wouldn't really use for soldering at all unless you can control temperature and air flow.

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Memblers
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Re: how to remove dip chip perfectly?

Post by Memblers » Sat Oct 19, 2019 9:52 am

At my workplace we use a Hakko FR-300 (looks like it's replaced by FR-301 now). It's possible to get by with something cheaper though. With a vacuum tool you need to clean it religiously, and keep the tip tinned when not in use so it doesn't oxidize. I bought a cheapo vacuum pump desoldering tool for home use, but it's kind of useless because the tip just dissolves away. Once the plating is gone, it doesn't conduct heat as well.

That's if you want to preserve the board and the chip. If you just want one or the other, it's a little easier.

nocash
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Re: how to remove dip chip perfectly?

Post by nocash » Sat Oct 19, 2019 1:17 pm

For normal/home use, a desoldering pump in $2 range should be just fine.
They are cheap and simple and the tip is made of plastic - and nethertheless doesn't tend melt away : )

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tokumaru
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Re: how to remove dip chip perfectly?

Post by tokumaru » Mon Oct 21, 2019 4:27 pm

I normally use something to hold the board up at 90°, then I heat the pins up from one side using the soldering iron while sucking the solder with a pump from the other side.

FrankWDoom
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Re: how to remove dip chip perfectly?

Post by FrankWDoom » Mon Oct 21, 2019 4:37 pm

Hakko guns are the best. If you're using it heavily it's worth the investment.

The pencil style desoldering irons work but burn up tips like crazy. Also clumsy to use.

Nothing else is worth mentioning.

nixjoe
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Re: how to remove dip chip perfectly?

Post by nixjoe » Mon Oct 21, 2019 6:06 pm

Thanks for reply ,guys, I'm sucks with a desoldering pump ($2).ya, I'm dealing with it with 90 degree cartridge setup and remove most soldering then still need the heatgun....
I'm using a heatgun which provide 200c to 480c , how about the temprature control? any recommand?

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Ben Boldt
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Re: how to remove dip chip perfectly?

Post by Ben Boldt » Mon Oct 21, 2019 7:10 pm

Techni-tool makes the only good manual desoldering pump I have ever used:

https://www.ebay.com/itm/202270458116

Image

The little ones you usually find are not even half as good as that one.

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tokumaru
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Re: how to remove dip chip perfectly?

Post by tokumaru » Mon Oct 21, 2019 10:28 pm

Ben Boldt wrote:The little ones you usually find are not even half as good as that one.
But apparently they cost well below half the price!

nocash
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Re: how to remove dip chip perfectly?

Post by nocash » Tue Oct 22, 2019 10:26 am

nixjoe wrote:I'm sucks with a desoldering pump ($2).ya, I'm dealing with it with 90 degree cartridge setup
I've never tried that at 90 degrees. I just have the board flat on the table, with legs facing upwards, and then...
- put the pump in place, but not held vertically yet (only one edge of the tip touching the board, so that the solder point is still visible)
- heat up the soldering point with soldering iron (best with a 2-3mm tip, and with slightly more heat than usually)
- and then 3 things at once: pull the soldering iron away + turn the pump upwards and hold it vertically + push the trigger on the pump
nixjoe wrote:and remove most soldering then still need the heatgun....
If there is already a visible opening in the hole, but with the pin still being glued to one side of the hole: Use a pair of pincers to move the pin to the center of the hole (that's often working even in cold state, you can just break it free, without heating up the pin).

Btw. those $2 pumps exist in different sizes: Normally they are 15cm in length, and when I bought another one (per online order), I ended up with receiving a totally oversized 30cm pump. At first I didn't trust my eyes and couldn't stop laughing, but it's working quite well, and perhaps even a bit better than the smaller ones (which are fine, too).

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Ben Boldt
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Re: how to remove dip chip perfectly?

Post by Ben Boldt » Tue Oct 22, 2019 2:43 pm

A solder pot is probably the very best way to remove a DIP chip in perfect condition but it is pretty likely to bubble/ruin the board. It is kind of amazing though, you just set the board on there and the chip pulls right out with no resistance. Maybe if you had a lead solder pot and got your temperature just above melting, the board might be OK. The ones I am used to are lead free and cranked way up, and I have definitely bubbled an NES board when I tried it. Modern boards don't do that, not sure what changed.

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Memblers
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Re: how to remove dip chip perfectly?

Post by Memblers » Tue Oct 22, 2019 3:48 pm

It might sound non-intuitive, but sometimes to desolder something, you first need to add more solder to it. It helps distribute the heat. Especially if the suction didn't clear the through-hole in the first go, add more solder before trying again. It's important that the tip of the iron be clean too, to conduct the heat better.

Ground planes and large copper fills are where you'll encounter problems. It's very common in Nintendo's boards for the ground and VCC pins to be connected a solid mass of copper. All that metal acts as a heatsink, and will pull the heat away from the pins. I don't think it's usually too bad on carts, but it is very significant on the NES mainboard, when removing the CPU/PPU. What I do is heat the top side with a soldering iron, and the bottom side with the desoldering iron, at the same time. In this case, the wattage of the heater is more important than the temperature.

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evilsim
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Re: how to remove dip chip perfectly?

Post by evilsim » Wed Nov 06, 2019 4:45 am

Memblers is spot on.

Whenever I am going to remove a Nintendo CPU/PPU I re-flow every pin with some solder, after putting flux everywhere.
Then I go and use my desolder station on each pin. I heat up each pin, then kind of move the tip of the desolder gun in a circular fashion whilst on the pin to properly wet all the solder, then suck it all away.

Usually the DIP will simply fall out of the socket once the last pin is cleaned of solder. If the solder gun stops working through the job (eg it needs a clean), I re-wet with lots of solder the pins I was working on and go back and de-solder the pins once the gun is clean.

Most of the hand-power solder pumps or the ones with an actuator in them work fine, but you just have to have pre-re-wetted and heavily fluxed pins.

Solder braid is the hardest option for a DIP chip in my opinion.

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