Translucent PCB substrate. - Page 1
Forum section: electronics / projects

author: Oneminde
author_rank: Regular Contributor
timestamp: April 07, 2017, 07:06:17 pm
content: Hello to all.You know how it is. You are looking for something specific and its very difficult to actually find it. I've spent my fair bit of time on this. I am looking for a translucent PCB / PCB substrate and that turned out to be somewhat difficult. So I am turning to EEVBlog to get assisted.I have attached a picture and here is the link to that picture. Its from a Luxman B-1000f amplifier.https://onahighernote.com/oahn/wp-content/uploads/2015/02/peel_coat_pcb_web.jpgIts definitely not standard FR4. But that is all I know. If you know something I don't or perhaps even know exactly what type of PCB it could be, please comment.

author: Zero999
author_rank: Super Contributor
timestamp: April 07, 2017, 07:09:49 pm
content: It looks uncoloured FR4 with no solder resist.

author: Oneminde
author_rank: Regular Contributor
timestamp: April 07, 2017, 07:19:50 pm
content: Quote from: Hero999 on April 07, 2017, 07:09:49 pmYeah there is definitely no solder resist as its not needed when gold plated. But where can one get uncoloured FR4 ?

author: Zero999
author_rank: Super Contributor
timestamp: April 07, 2017, 07:33:04 pm
content: Quote from: Oneminde on April 07, 2017, 07:19:50 pmSolder resist stops the solder from running down the tracks. It can also make the board more resistant to the track lifting.Uncoloured FR4 is very common for home made PCBs. If you buy fibre glass copper clad board (not the phenolic paper stuff) there's good chance it will be uncoloured. It's the solder resist which gives PCBs their colour.http://www.oldessexboy.co.uk/22.htmlhttp://www.oldessexboy.co.uk/resources/_wsb_652x489_P1010006.JPG

author: Oneminde
author_rank: Regular Contributor
timestamp: April 07, 2017, 07:40:37 pm
content: Sure, but looking at the photo you attached, that is how most of the FR4 looks, its not the same as on the Luxman.

author: senso
author_rank: Frequent Contributor
timestamp: April 07, 2017, 07:55:29 pm
content: Photoshop and other camera, the traces are gold plated and there is no soldermask, what else is different?

author: Oneminde
author_rank: Regular Contributor
timestamp: April 07, 2017, 08:18:01 pm
content: Quote from: senso on April 07, 2017, 07:55:29 pmI realize that camera settings, edit, lighting conditions matter. But looking at the reference photo I attached, I would say that the substrate lack color or pigments. Usually they are yellow, green or brown tinted. And I think I just found the substrate I am looking for.-->https://store.acpsales.com/products/2342/fiberglass-sheets-naturalBut for the sake of this thread and debate, here is another photo of the amplifier and I'll admit it looks a lot like ordinary FR4 (pale green):http://www.luxman.com/images/product/lux00013_20130805003103_128.jpg

author: Monkeh
author_rank: Super Contributor
timestamp: April 07, 2017, 08:23:50 pm
content: It certainly looks much smoother and more consistent than typical cheap FR4. It's a bit hard to find photos of bare substrate to compare with..It could be one of many controlled impedance substrates.

author: free_electron
author_rank: Super Contributor
timestamp: April 07, 2017, 08:28:09 pm
content: carbon composite resistors ? really ? those are the worst for noise .... there goes my respect for luxman.

author: Cerebus
author_rank: Super Contributor
timestamp: April 07, 2017, 08:29:10 pm
content: Quote from: Monkeh on April 07, 2017, 08:23:50 pmOr, as it's for a power amp, maybe a ceramic filled substrate (Rogers has a bunch of these) for better thermal properties.

author: Monkeh
author_rank: Super Contributor
timestamp: April 07, 2017, 08:33:13 pm
content: Quote from: Cerebus on April 07, 2017, 08:29:10 pmYep. That nice smooth milky white appearance looks awfully like PTFE..

author: Cerebus
author_rank: Super Contributor
timestamp: April 07, 2017, 08:34:35 pm
content: Quote from: free_electron on April 07, 2017, 08:28:09 pmCurrently a favourite for the Audiophool community. Obsolete Allen-Bradley carbon composition resistors are currently fetching quite a premium as I discovered when I was searching for some carbon composition resistors for an old multimeter repair recently.

author: langwadt
author_rank: Super Contributor
timestamp: April 07, 2017, 08:34:47 pm
content: rogers ?

author: Oneminde
author_rank: Regular Contributor
timestamp: April 07, 2017, 08:35:37 pm
content: Quote from: Cerebus on April 07, 2017, 08:29:10 pmI have RO4350B from Rogers, but it is a solid material. NICE substrate for sure and indeed very good for areas that are sensitive to FR and EM. Substrate is like the argument between 18 and 35 micron copper cladding.

author: Oneminde
author_rank: Regular Contributor
timestamp: April 07, 2017, 08:38:36 pm
content: Quote from: Monkeh on April 07, 2017, 08:33:13 pmPTFE is generally solid all the way through.

author: Cerebus
author_rank: Super Contributor
timestamp: April 07, 2017, 09:41:23 pm
content: Quote from: langwadt on April 07, 2017, 08:34:47 pmhttps://www.rogerscorp.com/makers of various high quality (and not inexpensive) PCB substrates especially ones intended for controlled impedance and RF work.

author: Oneminde
author_rank: Regular Contributor
timestamp: April 07, 2017, 09:58:44 pm
content: Yes, Rogers Corporation recommend RO4350B as a FR4 substitute when insulation from RF and EM is required and also offer a range of different thickness for the substrate. But be aware that this Hydrocarbon Ceramic substrate is many times more costly than standard FR4. Not so strange considering that RO4350B is often used in radio & telecommunication.

author: exmadscientist
author_rank: Frequent Contributor
timestamp: April 08, 2017, 01:17:42 am
content: I don't use large areas of non-masked substrate in my designs, but I've noticed that Isola FR408 is much whiter than any of the common FR4 materials. I can't be sure exactly how pure the white is, given the small areas exposed, but it sure looks white to me.One of the reasons I like to specify FR408 -- its good electrical properties aside; those are wasted on most of my stuff anyway -- is that it's distinctive enough that I can easily tell if the manufacturer has substituted cheap FR4 in place of what I specified. Though I guess they could be swapping in Rogers and I'd never know!

author: Oneminde
author_rank: Regular Contributor
timestamp: April 08, 2017, 10:05:57 am
content: Quote from: exmadscientist on April 08, 2017, 01:17:42 amThe whole reason for the hunt for translucent white substrate is the look Luxman achieve. Its a designer perspective. At least I am on the right path with ACP Composits. Isola does not show any pictures of their FR408 but it certainly does not hurt to investigate their product.If you have any pictures of the PCB's you manufacture using the FR408, don't hesitate to post so I could take a look.

author: mjkuwp
author_rank: Unknown
timestamp: April 08, 2017, 10:22:13 am
content: could the image from Luxman be a rendering? In other words it is not a photo, not 'Photo-shopped' but created totally from the CAD

author: Oneminde
author_rank: Regular Contributor
timestamp: April 08, 2017, 10:31:25 am
content: Quote from: mjkuwp on April 08, 2017, 10:22:13 amI sometimes work with 3D rendering and have seen high quality work, that photo is real - possibly with some edit before publish. For Luxman, this is nothing out of the ordinary, its just my obsession. Looking at some other photo's of the amplifier, the PCB seem more like standard FR4.Here is a link to available photos that I used in this thread.https://onahighernote.com/shop/mono-stereo-amps/b-1000f-monoblock/