feesible idea for soldering ic's?

It sounds like a great way to destroy the chip, and maybe the PC board's pads. It isn't that hard to hand solder small SMD packages. There are also "Dummy Components" and training boards available to practice on. They are used to teach hand soldering and rework in the real world.

Yeah but I was wondering about this idea specifically.

Why would it destroy the chip? If one *could* get the current to go only through leads into the pads then the chip doesn't see any current or voltage? Just curious why you think that? (not saying your wrong but for my own enlightenment... so don't get pissed like I'm calling you a liar or something. (Not saying that you'll get pissed but I know some people do))

My friend devised a way to hot air solder a number of SMT parts at one time by rigging a heat gun to blow hot air down onto the PCB, which had the parts placed on dots of solder paste. He had to rig up a diffuser for the air flow, however, as a standard heat gun will blow the parts off the board. It may also be possible to control the fan speed separately from the heating element, but that may cause the element and other parts of the gun to overheat. I think the diffuser was a fine mesh stainless steel screen, a few inches from the nozzle and very close to the board. Hand soldering is OK for simple prototypes and rework, but takes a long time for large boards or short run production.

Paul

How are you able to make sure that ZERO current flows through the IC? All it takes is a tiny revers bias into some inputs and the chip is scrap. If you method was viable, someone would already be selling the equipment to do it.

I can't. I said if. It might be possible but I do not know.

I don't buy the think "If it was possible then it would already be" argument because by that logic there would be nothing. You think the guy that invented the dildo(or maybe that was a girl) would have invented it if he thought that.

If you could make two contacts to the pad, or two contacts to the lead, you could heat one of them without driving current through either traces or leads. If you make one contact with the lead and one contact with the pad, and they are not in perfect contact with each other, you drive current through connecting traces and leads.

I have seen a method similar to this and I think a link was posted with video's on how to do it. I was just wondering about my specific example and if it would work at all. I would imagine if the voltage was low enough that it would be ok?

ISTR someone doing it with an electric frying pan.

But of course, there is resistance soldering. A low voltage, high current source, a couple of probes, and then you apply the probes to the lead you want to solder. The lead heats up, the solder melts and you've got your joint. It's been written about in the hobby magazines a few times over the years, and at least one gave a bunch of advantages of the method (though I can't recall them). Apparently it's better known in industry.

So the concept is out there, though it's always seemed risky, applying that sort of voltage source near components that are fragile.

Michael

I got the idea from them, and do most of my boards that way now too, on a $20 hotplate. Works great, esp if you make a stencil for the paste, but even if you hand-dab the paste on.

Sigh. No wonder your ideas stink, you're always thinking about dildos.

Hot air rework stations have been around for a LONG time. C&S Computers in Eustis Florida was upgrading memory boards for Data General minicomputers with a paint stripper gun almost 20 years ago.

I have never seen resistance soldering used for delicate work, let alone on CMOS components. I have seen it used to solder large terminals that don't wave solder, or to solder shields together. Its a crude, brute force method.

Do the math. The lower the voltage, the higher the current requirements. It becomes even harder to control the current distribution, making it even harder to control the temperature.

Huh?

V = IR

and P = V*I

Thats the math.

Whats your point? R is about, say, 10^(-3)?

If V = 1 then I = 1000A.

this means you have about 1000W instantaneous. You only need it for probably a few milliseconds if that.

If you need less current then you could lower the voltage or add some series resistance or even a current limiter or something.

You don't need to control the temperature. Its not some precision thing. Just need to supply enough current to meld the solder.

I would imagine 100W might do it just fine for about 1/10 to 1/5 a second. This means having a voltage of about 3/10V.

You could probably use sensors to monitor the power supplied. Obviously as it gets hotter the resistance will increase but this is pretty well known. Although if it gets to hot then it could destory other parts I do not think this is that big of an issue as it can be controlled.

As you pointed out, I think the real issue is current feeding into other parts of the circuit and into the ic.

Re: feesible idea for soldering ic's?

Re: Feasible idea for soldering ICs?

J>

Per pin.

Do you really think that a pulse like that will melt the solder properly?

Series resistance makes the voltage control even more of a problem.

Really? Then why do MEs spend hours or even days profiling a PC board for a reflow oven?

You're not a Vulcan, so I doubt that you can "Meld" solder.

Per pin, or a whole row of pins? The old Weller 8200 soldering gun is a high current, low voltage 100/140 watt soldering tool. It takes five seconds before its hot enough to melt solder. The lower the heat, the longer it takes, and the more damage it does to a PC board.

You've never worked at a plant that stuffed and soldered PC boards. I have. I've seen the best equipment available mess up, and require a lot of rework. I salvaged a handful of frequency counter boards years ago that another company tried to run through a wave solder machine that wasn't at the proper temperature. One of the boards had over a half pound of excess solder where the wave was a couple degrees too cold. It all solidified before the excess could run off. Reflow ovens have other problems, like solder balls, and partially melted solder paste that causes high resistance or open connections. I worked for four years inspecting reflowed boards under a stereo microscope, repairing any problems, then testing and calibrating the working boards.

There are too many variables to be sure you don't damage a LOT of parts.

and?

I have no idea and I'm sure you don't either. You claim to know the answers about everything yet I would bet you never have tried anything like this or even something that remotely resembles it.

Have you seen the cold heat? They melt solder just find with two AA's.

Every time you post I get the impression your one of those guys that think they know it all?

omg... man. shut the f*ck up. Your just one of those assholes who have to try and shoot down any idea because its not your own. I guess you get jealous cause your not creative enough to come up with your own ideas so you have to try and make every other idea an "impossibility". Oh, and BTW, reflow is totally f****ng different.

Then thats a total piece of shit. Do you mean that it takes 5 seconds to go from cold to hot? Ok... but after that it still takes 5 seconds to melt solder? My 40W one only takes about 1/2 a second.

THIS ISN'T FUCKING REFLOW. Damn man. You get some concept in your head and because you had bad experience with it then it must be impossible? I'm not trying to be an asshole or anything about you seem to be trying to find anything and everything that could cause problems to be a problem. It took Edison over 1000 tries to get the lightbuld to work... if he had the same mentality as you then wouldn't life suck.

What you don't realize is that I nevers said actually implementing it would be a piece of cake. There might be many problems... but the basic physics is what I'm talking about. If the physics are wrong then its impossible. If the physics are right then its just a matter of figuring out how to implement it.

I don't know... maybe. But sounds to me that your a quitter. Theres tons of variables in designing a moderning day cpu but the f****rs do it. Why? Because they don't give up like you do.

Seriously... you need to get over that defeatist attitude. Your basically worrying about things that you haven't tried but might not have any basis. Sure, you might be right... but then again you might be wrong. Just because there could be a large number of unknowns doesn't stop those that actually do it.

At the very least you should be like "I don't think it will work but you could try anways".

Why? Because if I fail then I fail... doesn't effect you. But if it works then it might effect you. It might be something you would use.

Instead though you try to make it seem like its impossible and its not worth trying. Why? If it does not effect you at all then what do you gain and what do you loose? As far as I can tell its only your ego thats in the way.

I hope your not that why with your kids(if you have any). You should encourage them even if you believe they might fail at it as long as they won't get hurt. There is a benefit to failing. I'd rather have my kid trying out some project that makes him think even if I think it won't work than have him watching TV. Who knows, he might supprise me and actually make it work.

Not that I'm your kid but I'm just saying that people like you who have that attitude that everything is impossible if they believe it is just really gets on my nerves. History has proven that they are wrong(and they only have to be wrong once for it to count).

So please do us all a favor and get over the ego trip. Its ok to point out problems but never say its impossible even if you have spend 40 years doing it and you believe it is.

Ok, asshole, do it and prove to the electronics industry that your f***ed up method will work. After all, they have spent billions of dollars for wave solder and reflow ovens, while you are the only one to come up with this piece of shit idea.

Yeah... I see. Seems your the asshole. I never f****ng said it was possible. All I said is that just because you say its impossible doesn't mean it is.

But all you do is get pissed off and only quote what you want so when people read your post they'll automatically side with you.

Doesn't matter because lucky for me I don't care about your opinion.... and thats all it is.

AGAIN!! ITS NOT FUCKING RELOW!!

In anycase I must put you on my ignore list(again... Is shouldn't have taken you off in the first place) because I know this conversation isn't going anywhere.