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VIDEO: how 4 layer boards are made

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EATyourGUITAR
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VIDEO: how 4 layer boards are made

Post by EATyourGUITAR » Thu Nov 25, 2021 9:50 am

the most interesting thing in this video is that people ordering 2oz copper or 4oz copper boards will have to work with a different min trace width and space between traces. the buchla people will enjoy the specifications for edge card connectors. the UV exposed resist was not the copper etch resist. the tin plating on the copper everywhere was the copper etch resist. they won't say what solvent they used for the masks.

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Reese P. Dubin
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Re: VIDEO: how 4 layer boards are made

Post by Reese P. Dubin » Thu Nov 25, 2021 3:30 pm

Did a job recently at work that was 8 layers at only 1.2mm thick. 14 different via combinations, with package on package BGAs.
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Re: VIDEO: how 4 layer boards are made

Post by guest » Thu Nov 25, 2021 6:14 pm

good info, thanks for posting.
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Don T
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Re: VIDEO: how 4 layer boards are made

Post by Don T » Fri Nov 26, 2021 12:49 am

I always wondered how they did vias and thru-plated holes. Thanks for posting!

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Re: VIDEO: how 4 layer boards are made

Post by jsleeio » Fri Nov 26, 2021 2:09 am

interesting that they route slots after e-test, I guess that's a place to be extra careful with clearances etc
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Re: VIDEO: how 4 layer boards are made

Post by EATyourGUITAR » Fri Nov 26, 2021 7:38 am

Something they mentioned in the video about plating the through holes was that they use a chemical process with increased throwing power. I worked for a company that manufactures electroplating machines. Everything is mostly 24V DC with time as a variable. But they told me that higher voltage low on time pulses where used for plating through holes because that was the only way it was possible to do it. They didn't tell me what voltage, frequency, or duty cycle. They only mentioned it in training to say that everything else it pretty much exactly the same voltage 24V DC. There are some machines I saw that were current controlled with an amp hour meter and a ready light. But that was always under 24V DC. Sometimes you see a machine that is 100A or 300A per tank. With a process that is high volume fully automated the big problem is keeping the concentration of chemicals consistent as chemicals are consumed in the process. I don't know how they do this. They would need another tank with fresh chemicals ready to go at all times. They can automate with valves when they think a tank is due to be cycled.
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Re: VIDEO: how 4 layer boards are made

Post by KSS » Sat Nov 27, 2021 5:36 am

Plating- anodizing industry still calls their power supplies 'rectifiers' which is what they mostly all were in the past. Most now use current-limited PSUs and plating and get better results. Higher throughput also. Most of the process lines i've seen were still using manual testing and chemical replacement. Even for lines running 24-7.
But the EDA software now provides enough detail on the actual copper metal amounts and ratios that even those doing this largely on their skill in measurement and experience as an 'art' have better feedback and expectations based on pre-process info to bring more 'science' into it. Factory control software is also more tightly integrated today.

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Re: VIDEO: how 4 layer boards are made

Post by EATyourGUITAR » Sat Nov 27, 2021 8:39 am

yeah I asked my boss why we call 24V DC bench power supplies "rectifiers". he told me that back in the beginning, there was a shaft + belt drive factory connected to a water wheel. They would connect an AC generator with a single diode. they did not have any equipment that could measure voltage. they controlled the speed of the plating by switching to different size pulley. if no plating happened then you need a little more speed on the motor.

I was a service technician. I definitely saw both setups. some where current controlled. some where voltage controlled. some were automated. some were manual. even if it was voltage control, it was always current limited to prevent damage to the power supply and the machine. we had something called an amp hour meter. you push to reset to 0. some machines would shut power off after the amp hour meter hit some number that would indicate the parts are likely good enough to be removed. these amp hour meters were using an OTA to integrate a saw and send a pulse to an UP counter. even if they didn't have a front panel amp hour meter for plating, they had one down in back of the machine on the power supply so we could charge them for mandatory service when everything was reaching end of life.
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