Talk:Rubylith

Chip layout

The cited article doesn't actually say that the Intel 4004 designers cut sheets of rubylith. Instead, it refers to narrow strips ("razor thin"), which seems to describe the rolls of narrow ribbon material shown in the photo. Those were in common use in that era for printed circuit board layout. So there is no cutting involved to make the strips, it's only a matter of using the roll with the right width of rubylith tape. In fact, if you were doing two-sided boards, you'd be using rolls like that, one set in red for one side of the board, the other in blue for the reverse side of the circuit board. The production process would take those two color layouts and convert them into negatives for the two sides by using colored filters. I did a PCB design in 1976 using that process. Paul Koning (talk) 14:02, 11 May 2012 (UTC)

No. The layout was done on graph paper with colored pencils. A layer was a giant sheet (scaled up die size) of rubylith. A coordinatograph was used to cut the outlines on the rubylith, and an Xacto knife was used to peel away the part that was not wanted. The result was an accurately cut master on a stable substrate. The lines were not "razor thin"; the cuts were razor thin (corners were overcut), but the peeled away portions were thick. They were not putting tape down on mylar. It would be awkward to do large diffusion wells with tape. And colored tape doesn't cut it when you have many layers. PCBs are a different story. There are a few fixed pad patterns and then a few conductor widths that can be done with tape. Glrx (talk) 05:25, 12 May 2012 (UTC)

This article is fairly inaccurate. User:Glrx is has it pretty much right. Rubylith had an approximately 0.005 in thick layer of red lacquer film on top of a 0.007 inch thick mylar base. I believe we bought it in 4 X 8 foot sheets. The coordinatograph was a XY stage (48 x 48" in my case) over an illuminated glass surface. The precision was 0.001 inch or better and could normally make cuts in the X or Y directions by moving the appropriate stage with the blade pointed in the correct direction of course. Other tools could be inserted into the head, for example a compass with a swivel blade to produce circles. The parts that needed to be removed were peeled off the mylar base leaving a clear opening. And, they were not always orthogonal cuts. If you were an artist, you could do interesting stuff. We did an XXX rated LCD for a wrist watch at one point. I need to go though my boxes, I know I have slides somewhere. I had a watch at one time. -- :- ) Don 00:38, 31 October 2012 (UTC)

Here you go. -- :- ) Don 00:42, 31 October 2012 (UTC)

And, here. -- :- ) Don 00:46, 31 October 2012 (UTC)

Lithographers tape image

This article includes an image of lithographers tape which is not in fact Rubylith. Pardon my ignorance but I do not know how to change this. StrawHousePig (talk) 15:20, 10 November 2012 (UTC)

I doubt lithographer's tape has a separate peelable film on it -- the user just wouldn't put the tape down in those places. But I'm not sure and don't have a reference.... Glrx (talk) 05:11, 13 November 2012 (UTC)

It is nothing like Rubylith beyond blocking the appropriate wavelength of light. It's basically identical to transparent tape (other than not being transparent of course). Again, the image attached to this Rubylith article is not an image of Rubylith and I do not see how to change that. I'm not even sure I'm doing *this* right. StrawHousePig (talk) 04:48, 14 November 2012 (UTC)

You are doing things exactly right. Lithographer's tape is commonly called "rubylith tape" even though it is not the film that is cut and peeled. Google rubylith tape. Also see the first paragraph of the article that says rubylith refers to generic masking films. I changed the caption, but it could be better. We could use an image of conventional rubylith. Glrx (talk) 06:26, 14 November 2012 (UTC)

I myself have never referred litho tape as rubylith tape because, well, it just isn't Rubylith. StrawHousePig (talk) 14:06, 15 January 2013 (UTC)

Ok, it's been 10 years, but does anyone object if I remove the image of lithographer's tape? It is confusing to have the main image for the Rubylith page show something that isn't Rubylith and is different from Rubylith. KenShirriff (talk) 00:30, 17 October 2023 (UTC)

Discontinued Production of Amberlith

During a recent episode of Adam Savage's "Tested", it was mentioned that Amberlith's production was discontinued. I updated the page here, but was unable to find a reliable source, even on the Ulano website (they seem to have completely dropped all mention of the product, or I managed to somehow overlook it.) I did find a vendor selling Amberlith backstock that made mention of when it was discontinued, and I have provided that as source, but I do apologize for being unable to find anything more rigorous. Corwin MacGregor (talk) 07:58, 4 August 2023 (UTC)