The Butterfly's big sister

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#1
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Success at last! This wasn't easy. I had some learning to do and I destroyed two Butterflies in the process.

P.S. Why do attachments appear in reverse order?

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Quote:
Why do attachments appear in reverse order?
Just like dinner plates on the shelf. Last in first out LIFO.

Nice work on the Butterfly!

Tom

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Cool work!

You are far braver than me.

Smiley

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What was the solution on the LCD/contrast problem?

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Very nice soldering job .... Impressed !

Nard

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tessa and Tina, You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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theusch wrote:
What was the solution on the LCD/contrast problem?

Lee

The problem was flux and flux remover under the chip. The problem I posted about earlier was a Butterfly I put a mega329pv on. I used paste flux on that one. On this mega649v I used liquid flux. Actually a Kester low-solids no-clean flux pen I got from Digikey.

I recommend the liquid flux for soldering the MLF packages that drive LCDs. For "normal" MLF chips, the paste flux works well.

It can take a long time for the flux remover under the chip to evaporate. In the meantime you won't have much of a display. Because of faint or missing segments, I soaked the mega329 board for several hours in flux remover. I then dried the board in front of a fan for several minutes as I always do. When I powered it on, the LCD was completely blank with no trace of any segments. I thought I killed it. So I left it in front of the fan for a few hours and it was still blank. I then left it in front of the fan overnight and now I have a fairly good display. It is still missing a couple of segments. I think it could stand some more soaking. Or maybe just more drying time.

With the mega649 and liquid flux I only cleaned the flux for a minute originally. The display worked but two display pins weren't working. I put some flux remover on the board and left it there for a few minutes and tried to blow some under the chip with compressed air. That fixed those two pins.

I guess I still have a viewing angle problem. It's not much of a problem actually. The mega649 display is best viewed from about 30 degrees below normal. It's not apparent, but that's what I did when I took the picture of the display. Looking directly on, the segments are faint.

The mega329 board is worse. The best viewing angle is 45 degrees or more. Some new Butterflies have this viewing angle problem also and I get used to it.

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Plons wrote:
Very nice soldering job .... Impressed !

Nard

Actually if conditions are right, drag soldering produces nice results automatically. All I do is run the soldering iron along the row of pads. The results do look rather spectacular, but you can do it too.

Of course what makes it possible to solder the MLF packages is the fact that the pads on the board extend beyond the chip enough to hit them with the iron. If the pads didn't peek out from under the chip, it wouldn't be possible to solder with an iron.

I tin the pads on the board and the pads on the chip first, and then put the chip on the board. The pads on the chip are at the edge of the chip and the ends of the pads are visible from the side of the chip. I make sure these ends are tinned also.

Getting the chip correctly aligned and nailed down when you do the dragging is another story.

You need some kind of flux present during the drag to prevent solder bridges. I guess you should have some solder on the iron also.

If the operation goes well, you can see a tiny fillet of solder in the corner between the end of the chip's pads and the board's pads.

I'm not an expert but I assume it best to use no-clean flux when soldering MLF packages. Even then, you may need to somehow clean under the chip if the chip directly drives an LCD.

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zoomcityzoom wrote:
Quote:
Why do attachments appear in reverse order?
Just like dinner plates on the shelf. Last in first out LIFO.

Tom

You'd think it would be mentioned in the FAQ. Maybe I should have searched for dinner plates? I thought this BBS was just giving me a hard time. :)

It could be worse though. One forum I use doesn't show the attachments in the preview. You have to hope and pray and click submit. But at least that forum puts the pictures in expected order.

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The photos are in the correct order on my screen :D

Tom

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You better have your eyeballs checked. It is still backwards here :)

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