ENIG Headaches

[somnif]

So, frustration venting time!

Spent the last couple days catching up on some projects that've been collecting metaphorical dust in my bin for a while. Among them, a few VFE boards. Lots of tiny 1/8W resistor pads all with that lovely gold finish.

And god damnit they seem damn near solder repellent at times. I know its a lot nicer for the environment, its more oxidation resistant for the boards over time, and its pretty, but good lord am I beginning to hate the stuff. My standard Kester solder just does not seem up to the challenge without a lot more heat than I prefer or am used to. (I know I can use some extra flux to make up the difference, but its still frustrating).

Anyone else experience this frustration? Or am I just going crazy from too much solder fumes in the past few days?

[BrianS]

Seem to have this problem with a few pads on every board.  Most take solder well then I get Twi or three that I have to keep at to get it to flow.  Using Kester solder also. I thought it was just me. 

[aion]

What formula are you using - 60/40 or 63/37?

I've been using ENIG exclusively for about two years now and never had any issues to speak of. It always takes quickly and forms a solid joint. I use 63/37, which is supposedly a little easier to work with, so that may be it.

[somnif]

Kester 63/37 No-clean. Its not every pad, its just the occasional little bugger that makes me want to toss the board across the room.

On normal 1/4W resistor pads its not really a problem, only when I'm doing tightly packed 1/8W sized things (or my surface mount comedy of errors from a few weeks back) that my headaches start to appear.

HASL finishes just wet better (in my experience). They're uneven, oxidize easily, and involve a metric butt load of lead, but I find them overall easier to work with. ENIG is prettier and more resilient, but just gets a bit frustrating at times.

[Leevibe]

Seem to have this problem with a few pads on every board.  Most take solder well then I get Twi or three that I have to keep at to get it to flow.  Using Kester solder also. I thought it was just me.

When you run into that issue, check to see if the problem pads are connected to a ground or power plane. If so, you're having trouble because all that extra copper makes a good heat sink.

[BrianS]

Seem to have this problem with a few pads on every board.  Most take solder well then I get Twi or three that I have to keep at to get it to flow.  Using Kester solder also. I thought it was just me.

When you run into that issue, check to see if the problem pads are connected to a ground or power plane. If so, you're having trouble because all that extra copper makes a good heat sink.

Thanks. That's very enlightening info.  That wouldn't have even crossed my mind. 

[aion]

Yes, that's a good thing to point out - thermals often take a tiny bit more effort depending on how wide the thermal tracks are. Also, what temperature are you guys running your irons?

[BrianS]

Yes, that's a good thing to point out - thermals often take a tiny bit more effort depending on how wide the thermal tracks are. Also, what temperature are you guys running your irons?

700 on mine.  I know that's a little hot but I try to get in/out quickly.

[aion]

Yes, that's a good thing to point out - thermals often take a tiny bit more effort depending on how wide the thermal tracks are. Also, what temperature are you guys running your irons?

700 on mine.  I know that's a little hot but I try to get in/out quickly.

I do 750 for everything, so 700 isn't too bad.

[alanp]

If I ever replace my iron I'm going to have to learn this temperature stuff -- I only have a plug-and-go pencil iron

[somnif]

If I ever replace my iron I'm going to have to learn this temperature stuff -- I only have a plug-and-go pencil iron

I adore my Hakko 888. Its so much nicer than my old pencil iron. Heats up in under a minute, holds that temp MUCH better so I can solder multiple things in a hurry, and even cools off a bit quicker so if I need to I can swap tips without needing to wait overnight. Its 100USD retail, but sales can net it for 70USD or less fairly often.

Plus, yeah, I can set the temp so I know I'm not going to melt something (My old 40W iron was stupidly hot and would oxidize the hell out of things).

Oh and for the saner parts of the world, 700F = ~370C