Author Topic: EEVblog #939 - How Is A PCB Manufactured  (Read 12604 times)

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Offline rrinker

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Re: EEVblog #939 - How Is A PCB Manufactured
« Reply #25 on: November 04, 2016, 04:57:36 pm »
Now that I've had a chance to watch Dave's video as well as the Tek one - it's kind of amazing how much HASN'T changed. Still a significant amount of manual operation.
 And that NC drill in the Tek video - now that is an old bit. GE C100 maybe, even older than the GE 550 we had at my first job - like the 550, the one in the Tek video does no storage of the program, it simply runs step by step reading the paper tape. After one run, the tape is rewound for the next set of boards. You can control stuff like feed rates, but you can't edit the program on the machine. The 550 dates from the mid 60's and lasted until GE released their first true CNC control in the 1050 in 1974 (we had one of those, too). The one in Tek's plant is much older, early 60's or maybe even late 50's vintage. But in our shop, that 550 was just as reliable as newer fancier controls and put in a full day's work every day, so no reason to replace it.
 Kind of funny watching the worker silkscreen on the photosensitive solder mask and labelling materials while Dave is saying "in the past this was a silkscreen process but now it's photosensitive" Yes, not really silkscreening when you have no pattern in the screen, but still funny.

Yeah, I was wondering about the drill in the Tek video. So, it's purely a mechanical solution then? No electronics? (Aside from the motors, naturally.)

I assume it works a bit like those old player pianos? I always wondered how they automated this sort of thing before CNC came about. The aforementioned pianos have been around since at least the mid to late 1800's, so I figured it would be something like that.

 No, there's plenty of electronics inside it. The tapes are coded with instructions that tell it to say move the X axis 5.845" positive, and the axis motors on machine tools like that are servo feedback, not steppers like on a cheap home unit or 3D printer - WAY more accurate and repeatable. I don't think those early ones could do repeating instructions, withotu a micro. SO if you wanted to move 5" left, drill, move 5" left, drill, 4 times you repeated the instructions on the tape. Once they had microprocessors, they could code repeat instructions so you could say 4x move left 5" and drill. Plus you just loaded the tape once, into the computer memory,a dn then stored it safely off the shop floor. The old 550 we had was retrofited with a simple 8080 based control box that fit onto the paper tape reader and had 7 lamps, one for each row, and you could run the paper tape through and it would store it in the 8080's memory and then play it back using the lamps feeding the reader. Very kludgy but it worked. It was an interesting time in my life, done with school and truly on my own for the first time. Didn't pay that well but I learned a lot of interesting things.


Offline nixfu

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Re: EEVblog #939 - How Is A PCB Manufactured
« Reply #26 on: November 07, 2016, 03:20:13 pm »
I can't believe how manual the process is. 

This makes me amazed at how cheap PCB's can be ordered from china. 

I thought they were cheap because of increased automation, and figured it was almost as automated as a pick/place/reflow process.

Offline seb30

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Re: EEVblog #939 - How Is A PCB Manufactured
« Reply #27 on: November 11, 2016, 06:52:42 pm »
Interesting video that answer a question I ask myself for a long time : why we must use a PTH hole for reference coordinate
in a design ? This is because PTH are drilled first and all the film are aligned on them !

Offline Deridex

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Re: EEVblog #939 - How Is A PCB Manufactured
« Reply #28 on: December 07, 2016, 06:35:37 pm »
Quite interresting Video, that showed me some sides of my work i didn't know.

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