PCBs as Front Panels ?

[Flounderguts]

While copper is a relatively ductile and soft metal in the high purity form that it comes on pcb panels, it does add stiffness because it does not *elongate* much as a plated material. Think of the copper as a thin ply adhered to the surface, and it adds quite a lot of tension. Actually, even a sheet of paper glued to the back makes a tremendous difference!

As an example, I made some 1u 19" PCB front panels. The single layer version was far too bendy wobbly to plug 1/4" jacks into, and I had to glue an aluminum angle to the back to make it usable.

The second version had copper and soldermask both sides...and it was stiff enough to plug in and out of, although it was still pretty bendy. I used 1.6 mm FR4 both times, although 2.0 mm would have been quite a bit stiffer, it wouldn't match up with the original panels. The degree of flex was exaggerated because 19", but it was amazing to me that I didn't have to use the aluminum angle on the second run...although I did anyway.

If the flex was extreme, I would expect to see either some cracking in the copper layer, or perhaps some wrinkling...I have seen neither one, but it is observably stiffer.

Another thing to consider is that the FR4 has a *front* and a *back.* The back has small pinholes in the surface from the manufacturing drive rollers. Most pcb companies pay zero attention to this, and if you aren't having it plated first (which fills up the pinholes and makes it dead flat), then you will be able to see the pinhole pattern in your soldermask, if you are unlucky enough to get tails when they load the FR4.

Anyway, that has been my experience with using PCB FR4 as front panels.

I totally agree with sealing the thin sides of the panels. I currently use a polyurethane product to do that, although acrylic seems fine as well. I used to use clear shellac because it dries so fast, but it also dissolves in alcohol, which didn't work so hot with the isopropyl I wipe them down with! If you can find a non-fuming cyanoacrylate, that would probably be best.

[EATyourGUITAR]

Does anyone know if it's possible to leave bare aluminum parts on a panel design by the masking layer or you wold see the dielectric layer?

usually there is no aluminum. usually it is fiberglass reinforced resin. layers of copper glued on. conformal coating. plating. silk screen. aluminum PCB's do exist but usually that is reserved for large LED lights that require the PCB to also be a heatsink. if you want to be the first person to order aluminum panels from a PCB fabricator then I will be interested to see pictures and prices. maybe the default thickness is too much?

[Flounderguts]

Does anyone know if it's possible to leave bare aluminum parts on a panel design by the masking layer or you wold see the dielectric layer?

usually there is no aluminum. usually it is fiberglass reinforced resin. layers of copper glued on. conformal coating. plating. silk screen. aluminum PCB's do exist but usually that is reserved for large LED lights that require the PCB to also be a heatsink. if you want to be the first person to order aluminum panels from a PCB fabricator then I will be interested to see pictures and prices. maybe the default thickness is too much?

I've done alucore pcbs before. There are several types, and if you leave all the layers above the core masked off, or blank, then it should come out bare aluminum. I have no idea if HASL or ENIG will stick to the bare aluminum in the processes that are used. They are both immersion processes, so that might be an issue. ENEPIG...I've done that on an alucore board before for wire placement, but we left one entire side of the board bare alu to stick it to a big heatsink, and I'm not sure what the process was.

Be prepared to pay...1000 of our final PCB boards (where we used cutouts to place heatsinks instead of using an entire aluminum pcb) was less than 10 alucore prototype boards. If you want aluminum panels, it's probably cheaper to buy aluminum sheet, have it cut with a fiber laser or mill, and then powder coat or paint it. Notice I didn't propose anodizing?

I might have an aluminum core pcb hiding in my office somewheres. If I can find one, I'll post some pix.

[medbot]

This thread continues to illuminate, thanks for the info. For my money, I don't pour on the top layer because I don't like the thin border it creates. It's subtle but noticeable when the panels are flush with each other.

I sprayed a set of panels with matte top coat because I wanted blue but not shiny and, after some experimenting, they turned out pretty nice.

[KSS]

I've looked into Al-cored PCBs quite extensively for my APT2500 project. They're not so expensive as long as you're only using one side SMD. IOW, the normal thing for LEDs and the like.

They do get CRAZY expensive when you add insulated through holes. Which makes sense when you look at the processes needed to do that.

I'd be surprised if you could get a plain aluminum look as the cores are already faced with dielectric on either one or both sides. That -dielectric layer- has to be non-etchable, as that's its reason for existence. So if you got them to screen print the 'underside' of a single-sided Alucore PCB it might be what you're after. But since that's not -at all- what they're typically doing, I expect it will cost more but the bigger issue may be getting it understood that you want the screen print on the *wrong* side.

[bgreeves]

I see, I thought you were implying that all the holes needed to be PTH. JLC's capabilities claim they go no larger than 6.35mm for PTH (and my holes for pots are ~7mm).

Yes I was. The method shown works for larger holes as the hole isn't drilled, it's routed or laser cut.

Will JLC plate such routed holes at no extra cost? If so, it seems weird to even include an upper limit to PTH size in their advertised capabilities...

[robotsounds]

I have done a few, This is a pcbpanel for the diy version of this module

It was designed with diptrace. Shiny bits are drawn on solder mask layer. The texture is a copper pour pattern, nice to prevent scratches and fingerprints. it was fabricated by jlcpcb in 2mm, new matte black.

69319B38-523C-4414-A77F-23A2B837A01B.jpeg

Wow, that looks great. Reminds me of my old AVO multi meters.

[jml]

I’m currently playing with the idea of building a module using a PCB as front panel to be able to integrate capacitive touch sensors. In case someone who has done that before is reading this: I’d be very interested in hearing your advice — what are design considerations to be aware of?

Looking at photos of modules that incorporate capacitive touch, e.g. Pressure Points and TSNM, I wonder: Are the golden lines the actual circuit or are those printed on top to protect it from wear?

[bgreeves]

I’m currently playing with the idea of building a module using a PCB as front panel to be able to integrate capacitive touch sensors. In case someone who has done that before is reading this: I’d be very interested in hearing your advice — what are design considerations to be aware of?

Looking at photos of modules that incorporate capacitive touch, e.g. Pressure Points and TSNM, I wonder: Are the golden lines the actual circuit or are those printed on top to protect it from wear?

I've been toying around with the same idea. There are numerous threads on here already if you just search for "capacitive" and "touch" in Music Tech DIY, from which I've learned quite a bit.

I know that TSNM is capacitive touch. I suspect that Pressure Points may be as well. Make Noise René I think might be resistive touch, which requires less circuitry but apparently frustrates some users whose skin can't reliably make a connection.

Regardless of whether they're resistive or capacitive, the golden lines are copper traces (most likely covered in ENIG surface finish for protection against oxidation), and yes they are in one way or another part of the circuit.

For a resistive touch circuit, the copper traces must be exposed so that the skin on the fingertip can complete the circuit.

For capacitive touch, the copper can be entirely hidden behind solder mask if you wish (see Doboz XIIO for example). However it can be left exposed for aesthetics, as you see with the TSNM (perhaps there is a functional reason to leave it exposed, but if so I'm not aware of what that reason is).

[KSS]

The CGS59 Touch SEQ and the CGS TRK Touch Responsive KBD are both good resources. Read also this Synapse article by Serge Tcherepnin under a pseudonym.

These are the 'unveiled' classics, but there are also modern capacitive sensing chips available today which offer dizzying possibilities. One of which is used in the Vectr Euro module, which is open source.

[bgreeves]

I used AllPCB aluminum process, I put the silkscreen on the back so on the Aluminum side.

As Raph points out, the milling was pretty rough; for what I'm doing that doesn't matter much except for the mounting holes, which look less than professional. I prefer ovals (to be able to snug things up on threaded strips), so I have three holes together, and that's probably part of why it's rough.

Has anybody tried printing both white and black on the bare aluminum substrate? Or even just more examples of any PCB panels printed on the bare aluminum substrate?

[bomby]

I asked PCBWay about printing on bare aluminum awhile back and they told me the solder mask would not adhere to it very well. With that in mind, that Frogleg Synthesis panel's silkscreen looks nicer than I would have anticipated, so maybe it would be OK.

From left to right in the below pic is (1) AllPCB aluminum panel, (2) JLCPCB FR4 panel with enig pour, (3) AllPCB aluminum panel, (4) JLCPCB FR4 panel with enig pour (just the reverse side of (2)), (5) JLCPCB FR4 panel with NO copper pour, (6) random blank panel.

(5) is really the only one I'm not crazy about. There are imperfections in all of them but IMO it's generally a really nice way to do panels for the price. A thicker font would have helped (5), but the soldermask and silkscreen are both generally a little rough there. I've noticed that in some of my other JLCPCB panels as well. The JLCPCB panels with the enig pour (2, 4) are a little older. I was surprised that those were JLCPCB when I checked because the solder mask/silkscreen are nice, smooth, and more matte than (5). I'm not sure if their process has changed, if having a copper pour makes a difference, or if using ENIG pushes them to bump up the quality all around. If I do another JLCPCB panel I'll try it with a basic HASL pour - maybe someone else can chime in here.

Hope it helps someone. Any questions, ask away. Been awhile since I've gone price-hunting but when I did I found JLCPCB to typically be the cheapest option (FR4 only), and AllPCB to be the cheapest aluminum panel option (PCBWay has more aluminum solder mask color options). Both very reasonable IMO. I'd suggest AllPCB aluminum unless you really want/need to minimize the cost. I have more examples if anyone wants more pics but it's really more of the same.

[Flounderguts]

^^ I concur.

If you're working with JLCPCB, silkscreen resolution and registration is generally mediocre *at best.* They simply regard it as placement information, and their engineers have made it clear to me that their equipment and processes for ss layer is not very tweakable.

But I was also told that they recognize the growing demand for pcb art and good silkscreen, and the rumor is that they are developing a DTB print technique that will allow 3 color process on top of soldermask. Hopefully, they will use UV cured resin inks for good durability.

For now, the best silkscreen options seem to be at PCBWay, but I urge you to try local prototype manufacturers. It *can* be pricey, but sitting down with a tech and showing them a picture of what you want to achieve is the best way to get it!

Or, learn to ss flatwork yourself! I've just discovered a local dude that does hand-masked anodizing that is AMAZING, using a combination of ss and anodizing techniques.

I have also heard that there is a new product in the soldermask supplier pipeline, and that is a *tintable* product...which will have both opaque and transparent base options. No metal-flake, though!!

[joeSeggiola]

Have you ever got an ugly uneven solder mask on JLCPCB black panels? In the last order I got this unpleasant surprise where 5 out of 15 black ENIG panels have this noticeable imperfections (see pictures below), as if the coating has thickened unevenly on the substrate. It is much more visible in real life than in photos, since the uneven areas reflect light very differently, highlighting the defect.

I sent a quality complaint, they replied apologizing and saying that it's a general problem in the "exposure process" for black boards, and that they will try to find a way to reduce this issue and improve the quality control next time. Anyway the other 10 black boards in the same order are fine, like all the ones in my previous order, and it's not nuances: either the solder mask is completely defective, or it isn't at all...

They gave me a partial refund for this time only, and warned me that the only way to make sure it doesn't happen again is to not choose the black color... A production issue can happen, but this answer left me very disappointed...

[040B]

Have you ever got an ugly uneven solder mask on JLCPCB black panels? In the last order I got this unpleasant surprise where 5 out of 15 black ENIG panels have this noticeable imperfections (see pictures below), as if the coating has thickened unevenly on the substrate. It is much more visible in real life than in photos, since the uneven areas reflect light very differently, highlighting the defect.


IMG_20210330_215920.jpg


I sent a quality complaint, they replied apologizing and saying that it's a general problem in the "exposure process" for black boards, and that they will try to find a way to reduce this issue and improve the quality control next time. Anyway the other 10 black boards in the same order are fine, like all the ones in my previous order, and it's not nuances: either the solder mask is completely defective, or it isn't at all...

They gave me a partial refund for this time only, and warned me that the only way to make sure it doesn't happen again is to not choose the black color... A production issue can happen, but this answer left me very disappointed...

Happened to me a few times before. They are not a panel fabrication company. For regular pcb’s this is not an issue ofcourse.

It seems to be bit of a gamble. I get 10x nice ones in a row, then 2x with specks or smears in the silkscreen.

[TomMAP]

Yeah those don't look particularly out of the ordinary for JLCPCB to me (unfortunately). Those look really cool otherwise Joe.

[KSS]

Welcome to MuffWiggler, TomMAP!

------------

They are not a panel fabrication company. For regular pcb’s this is not an issue ofcourse.

Yes. We've been lucky to get as good as we've generally got.

I do expect it will get better, per Flounderguts. I won't be surprised if a panel service becomes a forked process and costs more. We might then wish to get back to where we are now.

[040B]

For those of us that love pcb front panels.

For those that love FR4 front panels.

[ricko]

I have been trying out a front panel made from aluminium PCB material: Allpcb is so cheap for this.

I don't much like having the panel touching the metal sleeve of the sockets. Like a Moog modular in the 60s! (Sure, it is module 0V but that is not necessarily ground or earth.)

For perpendicular PCBs, it is no problem: just adopt Laurie's approach in the Elby modules and use the Cliff sockets with plastic necks. https://www.elby-designs.com/webtek/ima ... -jacks.jpg

But is anyone aware of insulated sockets for parallel-mounted PCBs? I found this: https://www.amplifiedparts.com/products ... r-pc-mount

(I guess at a pinch I could use bigger holes with grommets on them for insulation.)

[KSS]

The older style qingPu jacks* -then known as flight jacks, and later Erthenvar- may be used in either isolated or conductive mode. For isolated one uses a 5/16 or 8mm panel hole and a non-conductive washer under the panel nut. The jack has a double-D rounded raised plastic boss molded into the jack body which fits this setup perfectly.

*used also on TTSH PCBs.

The issue with this choice is that those jacks were updated to their present square boss in an attempt to prevent loosening with use. This loosening is-was a result of the threaded bushing having only a thin, short swaged connection to the internal Jack GND or 0V metal. When one tightened the nut excessively -and even with normal use- the threaded portion would pull free because the swaged part wasn't strong enough to fully resist the forces involved.

I've used CA, Silver solder and tried epoxy to fix this probem for these jacks. All work. The best is silver solder. I clamp a cheap soldering iron upright and since these irons have a cheap single screw holding the tip, I replace it with a brass rod sized to just fit inside the jack hole. In this way I can manually bring the jack down over the hot rod in one hand, and apply the silver solder with the other hand. Easily lifting the jack by its body once the silver solder flows.

Silver solder used so its higher temperature counteracts the following tempuerature encountered when soldering the jack to a PCB or fly wires.

The CA also works well -and is much simpler and faster- but I worry about conductivity over time. Epoxy is not a good choice in my experience.Too messy and requires larger qty which must be carefully arranged orit interferes with jack function. Capillary action eliminates this concern for the silver solder and CA methods.

Of course the best choice would be for the mfr to make a longer, stronger and proper swage. But they feel they've 'solved' the problem with the square boss. It does solve theone problem, but creates another. The once present ability to use the same P/N for both insulated or conductive to panel use is no longer available.

[joeSeggiola]

Happened to me a few times before. They are not a panel fabrication company. For regular pcb’s this is not an issue ofcourse.
It seems to be bit of a gamble. I get 10x nice ones in a row, then 2x with specks or smears in the silkscreen.

Yeah those don't look particularly out of the ordinary for JLCPCB to me (unfortunately). Those look really cool otherwise Joe.

Then I guess there isn't much I can do. It's sad however, since it's the only factory I found with nice shipping options for small quantities: for example ePacket is quite cheap and you can pay customs in advance without any surprise fee when the package is delivered at your door... Another thing they've said to me is that bigger solder mask areas are more likely to show that imperfections. That makes sense considered regular PCB are surely more packed, and if you look at my pictures you'll see the solder mask is more regular about 3mm around any feature.

I think I'll try AllPCB next, since I don't enjoy gambling. I just had a correspondence with their customer service, I told them about the issue and showed them the photos, they said they do it better and don't have this problem... I'm not naive enough to take their word for it, but it's something... What's your experience? How is their matte black, if anyone got panels made by them? (edit: I just searched this topic, thanks @ricko, @elmegil, @bomby). Prices look good, they also have aluminum and it's not expensive, but shipping options and customs duties don't look as transparent as JLCPCB's.

I do expect it will get better, per Flounderguts. I won't be surprised if a panel service becomes a forked process and costs more.

We'll see!

[Flounderguts]

What's your experience? How is their matte black, if anyone got panels made by them? Prices looks good, they also have aluminum and it's not expensive, but shipping options don't look as transparent as JLCPCB's.

I'm not sure if you saw a few pages back, when I mentioned that they DO NOT take time to orient their FR4. The raw FR4 has a TOP and a BOTTOM, with the bottom having small injection sprue nubs, as well as a very glossy finish and a bit of weave texture. When the panels go in with the FR4 bottom facing up (for your top), they can show the little nubs and the weave through the mask. Also, if the soldermask goes directly on the FR4, then it has a different, glossier sheen.

That is why I always recommend that people use a copper layer under the solder mask BY DEFAULT. Soldermask on copper has a consistent sheen, and the copper layer hides the nubs and weave. Why go through the trouble of making text on the copper layer, and exposing it carefully with soldermask, which requires extra registration? Just plate the entire surface in a copper layer, and use the soldermask layer to expose the bits you want to see! If having that layer contacting your pots or switch bushings is a concern, then just put those holes on their own little islands or holes in the copper layer.

Also, alumicore pcb material sometimes has a texture as well...not a weave, but very subtle tracks in the bottom layer, a bit like caterpillar tread marks. My micrometer wasn't able to measure the depth, but I used an optical comparator, and they appear to be about 2 or 3 tenths (1/10000th) deep...enough to see or feel a bit.

The bottom line is that if you want aluminum panels, it's best to get aluminum panels...rather than LED heat-dissipating PCB core panels. Because that's NOT what they are designed for.

Here's a question...if I were to offer panel-making services in aluminum or steel, with silkscreen and laser etching services, what would that be worth to people? I have the tooling available...

[PabloSrNaranja]

95846056-46FE-4B77-9954-156ADB3099F2.jpeg

For those that love FR4 front panels.

woow, so nice!

[bgreeves]

Here's a question...if I were to offer panel-making services in aluminum or steel, with silkscreen and laser etching services, what would that be worth to people? I have the tooling available...

This sounds worth starting a new thread about.

[joeSeggiola]

Thanks for the info, Flounderguts.

I'm not sure if you saw a few pages back, when I mentioned that they DO NOT take time to orient their FR4. The raw FR4 has a TOP and a BOTTOM [...] That is why I always recommend that people use a copper layer under the solder mask BY DEFAULT. Soldermask on copper has a consistent sheen, and the copper layer hides the nubs and weave [...] Just plate the entire surface in a copper layer, and use the soldermask layer to expose the bits you want to see!

No, I missed it. That's precious info, and I think I'll do that way. I read somewhere AllPCB black is "more matte" than JLCPCB's, so I hope the copper layer won't make the panel look too much reflective (which I wouldn't like). That said, on my latest JLCPCB order I tested this on the back layer, in fact: full copper covered entirely with solder mask: it wasn't too much reflective, but also had that same imperfections I showed

if I were to offer panel-making services in aluminum or steel, with silkscreen and laser etching services, what would that be worth to people?

I have no idea what the fair price would be, like, for any of this really. I'm a total newbie, I just learned during this winter lockdown that designing and ordering custom made PCBs is not as difficult and expensive as I would have imagined. I'm just testing factories and looking for the best options, I'm not a professional.