A bit OT, but the board for the iPhone5 is quite an extreme example of surface mount density:
http://www.bunniestudios.com/blog/?p=3206
(Click through for full resolution)

Garth, I respectfully disagree. I found my .064" boards to have enough flex over a 3" board that I am concerned just a little. I've done a lot of work with etching .032" boards in a makeshift environment - and like it a lot as the boards fit through a modified laminator. The boards are fairly flexible, and I would not trust a BGA to sit tightly on them.

The main issue with flexing happens during the hotplate heating process. .064" boards (3" long) start warping as they heat, lifting the edges a tiny bit. While the amount of flex is minimal enough to not be a problem, I would expect problems with a thinner board.

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In theory, there is no difference between theory and practice. In practice, there is. ...Jan van de Snepscheut

Ah yes-- I was forgetting about the flex issue with BGAs, and only thinking about trying recently to break a 1/4"-wide piece of .062"-thick frame that comes from a subpanel with multiple boards in it. I couldn't believe how hard it was to break even though it was only 1/4" wide. With reasonable board handling followed by installation in a case that holds it straight, the board should be safe. I have in front of me a 4-layer .032"-thick board that went into a PCMCIA hard-disc drive, but although it has fine-pitch SMT, it does not have BGAs. OTOH, if the boards are flexing merely from heating and cooling, the force applied to the solder balls will probably be much greater with the thicker board, regardless of the mills-per-inch warpage.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Good point about the force. I am hoping that the cooling in particular does not dislodge the newly-formed welds. I suppose I should get the oven to work...

A 4-layer board may be different from the 2-layer boards I've been working with. Like plywood, it may be much sturdier.

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In theory, there is no difference between theory and practice. In practice, there is. ...Jan van de Snepscheut

So it might be worth letting a newly soldered board just cool down on the block of Al, instead of moving it and shocking it not only by movement but also temp...
A pro oven is looking better all the time IMO.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502

I'm using a 4-layer, .062" thick board...
I've used these smallest vias in all versions of the parallel video video board. As far as plating is concerned, where is the problem? I intend to manually fill these in with solder... I do know ExpressPCB does say that these vias may or may not be filled-in with solder. I've received about 12 boards from them now, and not one has been filled. Not that any of this matters, just an observation.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502

I wasn't thinking of whether they would be filled in or not, but rather that the thru-plating actually get all the way in to the middle and make a dependable connection from one side to the other at that point (as well as to connect to inner layers). If the thru-plating doesn't make it all the way through, it might also be hard to get solder to wick all the way in there to make a connection.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

It is laughable that any company would advertise some kind of ability like this small via through hole plating to any of the other 3 layers and yet the possibility is there for a failed connection.
In my own experience with this company, I've not seen this type of failure using ExpressPCB yet.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502

Leaving the board on the hotplate would probably result in a smoky mess - I keep my plate way too hot - the board stays on it for about a minute with some smoke visible.

I haven't measured the cooling rate of my hotplate block (usually I move on to other tasks after a few minutes of using it) but it takes an hour or so to cool down.


One of the original hotplates I based my design on has a cooling fan underneath.

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In theory, there is no difference between theory and practice. In practice, there is. ...Jan van de Snepscheut

Also, I think the quality of the solder joints is improved by fairly rapid cooling.

6502 Playground rev.D boards just arrived, and I assembled one without any issues (BGA484).

If I had to do it over, I would avoid placing components on the back side. Even with an oven it is much easier to paste the board when the backside is nice and flat and not worry about anything falling off. With a hotplate, anything on the backside has to be soldered by hand.

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In theory, there is no difference between theory and practice. In practice, there is. ...Jan van de Snepscheut

This thread is very useful to keep us 'makers' at least close to the leading edge of what technology has to offer as far as IC's available and PCB production to utilize them without spending money on an evaluation board...

I thought I would pass along a couple links to videos that piqued my interest that I've found recently on another websites' thread regarding PCB production and the mounting of surface mount devices. Personally, it re-sparked my interest in board design because it is comparatively cheap to another service I was using, and the old service is only capable of 4 layer boards and does not provide a stencil option. This new service is capable of 16 layers. One can price different options without even logging in. There's every imaginable option available. They are in EU, but they seem to ship worldwide at reasonable prices. Check the video link below for how the stencil works to apply solder to the board before solder surface mount tech, especially BGAs.

Here is the original thread posted by another member who has similar concerns to mine.

Here is the video on how to use their stencils to lay down the solder using their stencil and their PVB. Stencil is only another $50 per layer (top or bottom).

I'm still doing research on how much the stencil "JIG" costs

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65Org16:https://github.com/ElEctric-EyE/verilog-6502

Well, I was unable to learn the Eagle PCB payout program in any reasonable amount of time, so I gave up on this idea. But I still pursue mount a 256-pin 1mm BGA Xilinx Spartan 6 LX25 device.

I have purchased the USB microscope mentioned earlier. Note the megapixel count has gone up from 2 or 3? up to 5MP.
I placed it about 2 inches above the hotplate during heating up to 265degC. I was expecting fogging or melting or something, but no such bad luck.
A neodymium magnet was placed behind the non-slip covering, that's what's keeping it on the metal cookie box. I would like to make a wooden jig tomorrow so the camera doesn't move in relation to the hotplate.
As it is now, this is what I'm working with. The 2nd Al alloy plate was placed on top so I could do a quick pic, since the bottom plate was still up to temp.
I just plugged the PID controller real quick to make it look live.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502

Using a fresh board from an old 6502SoC design, I needed to test soldering in some 0603 536ohm resisitors. For solder paste, I'm using ChipQuick part # SMD291AX10.
The first run wasn't very successful, as I attempted to use their fine tip dispenser.
You can see some before and after pics using the USB scope.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502

Now with my 'special' needle dispenser, I have a much better result.
I didn't think to do a before pic, but it is about 1/3 of the solder paste in the above 'Before' pic.
I hardly put anything down but it still looks like a tad much!

I can say I am absolutely amazed at how the parts centered themselves due to the solder reaching its melting point and the surface tension of the liquid solder.

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65Org16:https://github.com/ElEctric-EyE/verilog-6502