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plasmo
PostPosted: Thu Jan 06, 2022 1:45 am 
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Oh my, looky what we have here!

Sent the designs off day after Christmas and received them back today. It took them longer than normal probably because of the holidays and 3 of them are 4-layer boards. One of them is even gold plated (ENIG). Five of these boards are 6502 or 65816 related. Two of them are accelerators for Apple II, my latest distraction. So, it will be "Fun fun fun 'til mommy takes the soldering gun away" :P
Bill


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sburrow
PostPosted: Thu Jan 06, 2022 2:27 am 
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Lookin' good!

On the top-middle and bottom-right, you have some very serious surface-mount chips, like a bazillion tiny pins! How DO you solder those things on??? L33t hax0r skills? :)

(Seriously, I'd like to know.)

Chad
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barrym95838
PostPosted: Thu Jan 06, 2022 2:34 am 
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You have a white cat helping you with your projects, don't you?

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Hermione likes to help us around the house too.

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plasmo
PostPosted: Thu Jan 06, 2022 3:00 am 
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sburrow wrote:
Lookin' good!

On the top-middle and bottom-right, you have some very serious surface-mount chips, like a bazillion tiny pins! How DO you solder those things on??? L33t hax0r skills? :)

(Seriously, I'd like to know.)

Chad

The top middle is Altera EPM7192SQC160, 160-pin quad flat pack. Bottom right is EPM7128SQC100, 100-pin QFP. These are hand soldered, one pin at a time, under microscope. Need practices to master it. The secret is small-tipped soldering iron, small diameter solder, flux, and magnifier.

barrym95838 wrote:
You have a white cat helping you with your projects, don't you?

I have two white dogs (Westie), but I think that's just old age. Well, at least I still have some hairs left... :roll:

Bill
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GARTHWILSON
PostPosted: Thu Jan 06, 2022 3:21 am 
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sburrow wrote:
On the top-middle and bottom-right, you have some very serious surface-mount chips, like a bazillion tiny pins! How DO you solder those things on??? L33t hax0r skills? :)

You don't solder one pin at a time. I soldered the SOJ's in the second picture of BDD's post here with a 1/8" chisel tip that covers three pins at once. I don't even use extra flux. Somewhere we have a topic about soldering finer-pitched stuff with different techniques. Maybe someone else can remember appropriate search terms better than I seem to be able to.

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plasmo
PostPosted: Thu Jan 06, 2022 3:37 am 
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Yes, drag soldering works as well. I had an assembler whom I worked with for 20+ years. She took her time soldering the 4 corners and then drag solder each side in few seconds. Amazingly fast.
Bill
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plasmo
PostPosted: Thu Jan 06, 2022 4:20 am 
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Since we are talking about it, I want to solder one up to check out the new QFP160 footprint. The old footprint had some misalignment and the landing area for the solder tip is too narrow. Now I have soldered one up, I'm happy with the footprint. Something I've learned over the years is that footprint for hand soldering is different than machine soldered footprint. The standard library footprints are for machine soldering and need to be modified for hand assembly.
Bill


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BigDumbDinosaur
PostPosted: Thu Jan 06, 2022 7:20 am 
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plasmo wrote:
Since we are talking about it, I want to solder one up to check out the new QFP160 footprint. The old footprint had some misalignment and the landing area for the solder tip is too narrow. Now I have soldered one up, I'm happy with the footprint. Something I've learned over the years is that footprint for hand soldering is different than machine soldered footprint. The standard library footprints are for machine soldering and need to be modified for hand assembly.
Bill

Looking at your board reminds me of a time when 90 degree corners in traces were an invitation to disaster. What would happen is the etching solution would sneak under the photo-resist and eat more copper off the sharp, outside corner than the inside corner, thinning out the trace. Eventually some such traces would open up.

When I was taught how to design PCBs (many years ago), I was admonished to use two closely-spaced 45 degree corners to avoid the thin trace problem (I still do this out of habit). Fortunately, processes have improved since then. Even so, some board houses still caution against using 90 degree bends on trace widths under 10 mils.

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plasmo
PostPosted: Thu Jan 06, 2022 1:24 pm 
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The "no 90 degree acid trap" prohibition was a valid concern in the last century, but not an issue anymore. You can verify that by zooming in the image and see the corners of 7 mil traces are not over-etched. Having said that, I also know I can open up 100 modern electronics and find no 90 degree corner in any of the 100 pc boards. It is a rule that every board designer follow (except a few black sheep). It is like the "must wearing jacket in fancy restaurants" rule that everyone just follow.
Bill
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AndrewP
PostPosted: Thu Jan 06, 2022 3:16 pm 
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Live and learn. I'd always been told 90° bends could cause single integrity problems. I had no idea it was actually an old manufacturing process issue. In fairness I might have been told this by a radio astronomer as the department I was with had strong ties with the Hartebeesthoek Radio Telescope.
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plasmo
PostPosted: Thu Jan 06, 2022 3:50 pm 
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AndrewP wrote:
Live and learn. I'd always been told 90° bends could cause single integrity problems. I had no idea it was actually an old manufacturing process issue. In fairness I might have been told this by a radio astronomer as the department I was with had strong ties with the Hartebeesthoek Radio Telescope.

It definitely is a signal integrity issue above multiple hundreds of megahertz. Thankfully we don't have to worry about that in the retro community.
Bill
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BigDumbDinosaur
PostPosted: Thu Jan 06, 2022 5:02 pm 
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plasmo wrote:
The "no 90 degree acid trap" prohibition was a valid concern in the last century, but not an issue anymore.

As I noted...processes have greatly improved.

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...I also know I can open up 100 modern electronics and find no 90 degree corner in any of the 100 pc boards. It is a rule that every board designer follow (except a few black sheep). It is like the "must wearing jacket in fancy restaurants" rule that everyone just follow.

And there are restaurants that won't admit you unless you are wearing a jacket and in some cases, a tie. I and some clients once got kicked out of such a restaurant in San Diego in the 1970s. Too bad the Internet and Yelp weren't around back then. I would have been merciless. :D

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AndrewP wrote:
Live and learn. I'd always been told 90° bends could cause single integrity problems. I had no idea it was actually an old manufacturing process issue. In fairness I might have been told this by a radio astronomer as the department I was with had strong ties with the Hartebeesthoek Radio Telescope.

It definitely is a signal integrity issue above multiple hundreds of megahertz. Thankfully we don't have to worry about that in the retro community.
Bill

Be sure to let us know when you get your 65C02 project running over 100 MHz. :D

BTW, I recall reading somewhere sometime ago that Bill Mensch had opined that if the processes used to make the cores of AMD's Opteron processors were used to produce the 65C02's core it would likely be capable of 10 GHz. What fun would that be! :shock:

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GARTHWILSON
PostPosted: Thu Jan 06, 2022 8:43 pm 
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plasmo wrote:
AndrewP wrote:
Live and learn. I'd always been told 90° bends could cause single integrity problems. I had no idea it was actually an old manufacturing process issue. In fairness I might have been told this by a radio astronomer as the department I was with had strong ties with the Hartebeesthoek Radio Telescope.

It definitely is a signal integrity issue above multiple hundreds of megahertz. Thankfully we don't have to worry about that in the retro community.
Bill

Please see what Dr. Howard Johnson writes in his article, "Who's Afraid of the Big, Band Bend?" at https://web.archive.org/web/20110910025 ... adbend.htm, first published in EDN magazine, May 2000 which is where I first saw it. Even in the fastest digital work, the 90° bends on small traces absolutely do not present a performance problem.

Decades ago when I was etching my own boards with ferric chloride from Radio Shack, I found that the insides of sharp corners would corrode, from not rinsing all the etchant out. I started really scrubbing the boards after etching, the soaking longer and scrubbing some more, trying to get the etchant all out; but try as I may, all it did was make it take longer to develop enough corrosion to see. It still appeared after a while though. So after I started laying out boards to be made commercially in the mid-1980's, I avoided the sharp corners. It's not necessary anymore, but it doesn't cost me a thing to keep doing it.

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BigDumbDinosaur
PostPosted: Fri Jan 07, 2022 5:04 am 
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GARTHWILSON wrote:
Please see what Dr. Howard Johnson writes in his article, "Who's Afraid of the Big, Band Bend?" at https://web.archive.org/web/20110910025 ... adbend.htm, first published in EDN magazine, May 2000 which is where I first saw it. Even in the fastest digital work, the 90° bends on small traces absolutely do not present a performance problem.

For the benefit of anyone who isn’t familiar with Dr. Johnson, when it comes to high-speed digital design, he is an expert among experts. If he says a sharp corner won't affect signal propagation in a meaningful way you can take it to the bank.

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So after I started laying out boards to be made commercially in the mid-1980's, I avoided the sharp corners. It's not necessary anymore, but it doesn't cost me a thing to keep doing it.

I continue to use two 45s instead of one 90. Although the reason for it has pretty much disappeared with modern processes, old habits die hard. BTW, I still use wide greenbar paper in my Oki ML395 printer. While the old 395 (I've had it for 25 years, and it was a refurb when I bought it) can't match the speed of a laser, it and the wide paper are the cat’s meow for dumping program listings.

Incidentally, here’s the layout for a controller PCB I designed for use in a riding-scale locomotive. It’s a four-layer design and is about 10 inches (25.4mm) wide. Note the absence of 90 degree bends in the traces...old habits die hard. :D

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BigEd
PostPosted: Fri Jan 07, 2022 8:37 am 
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I like diagonal routing too, but for a different reason: you can get more in. In BDD's example above, there are three traces on the lower right which weave between a via and a fixing hole. Along the lower edge there are four parallel traces which need to jog inboard as they go left. In both cases, being restricted to right angles will use up a lot more room.

(Inmos' CAS system used an octagonal system for routing in their transputer family chips, and it was great to use!)
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