Source for RF Sheilding Cans? - Page 1
Forum section: electronics / projects

author: edpalmer42
author_rank: Super Contributor
timestamp: November 01, 2021, 12:00:11 am
content: Can anyone suggest a good source for the RF shields that are soldered onto a circuit board to block RF interference either entering or leaving a section of the circuit? They're typically made of tin-coated steel and have a friction-fit top.I've looked around and have found a very limited selection that's very expensive. It seems like most of these items are custom-designed but since I only need a few, that's not an option.I've checked all the usual sources that I can think of.- google, electronic distributors, ebay, aliexpress, etc. At this point, I'm considering using small tin-plated steel boxes and modifying as necessary.Thanks,Ed

author: bob91343
author_rank: Super Contributor
timestamp: November 01, 2021, 12:08:49 am
content: You have pretty much done all you can do. Maybe you can cannibalize a unit. My signal generators are full of those cans. I have seen people use cans from Altoids.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 01, 2021, 12:16:13 am
content: https://www.digikey.ca/en/products/detail/leader-tech-inc/SMS-201F/7203528orhttps://www.digikey.ca/catalog/en/partgroup/two-piece-circuit-board-shields-cbs-10-20-40-50-and-80-series/69165https://leadertechinc.com/assets/files/catalogs/cbs.pdfAlthough the prices are pretty high but they didn't used to be. Basically you have a strip with through hole pins, you fold it along the dents and you order the cover.You didn't mention size at all.

author: BrokenYugo
author_rank: Super Contributor
timestamp: November 01, 2021, 12:56:33 am
content: For just a few could you cut and bend your own out of brass sheet? I've also seen pieces of copper clad PCB soldered into a shielding box.

author: ricko_uk
author_rank: Super Contributor
timestamp: November 01, 2021, 01:16:06 am
content: Wurth (we does quite an extensive range. Some also have the cover that you can remove):https://www.we-online.com/catalog/en/pbs/emc_components/emi_shielding_material/board-level-shieldingalso Harwin:https://www.harwin.com/connectors-hardware/emc-shielding/rfi-shield-cans/?gclid=Cj0KCQjw_fiLBhDOARIsAF4khR0cHFBUDF7xzP1JbJ1RDOBSbUzuyCzmll65i5-gx6wfLsrY7WZZop4aAmlbEALw_wcB

author: edpalmer42
author_rank: Super Contributor
timestamp: November 01, 2021, 02:42:49 am
content: Thanks for the links and ideas guys. But it seems that all the economical shields are too small and the ones that are an interesting size are crazy expensive. Harwin has an interesting kit to build your own, but it costs C$35 from Mouser and I'll need 3 or 4 of them.I didn't mention size because I have to decide how to shield the circuits before I finalize the designs. But they will be relatively large due to some through hole components. That's the other problem - these days most of the high-volume, lower price items are for surface mount devices.I have considered building them myself. I hadn't thought of brass - it's worth considering. I did find that it's economical to buy sheets of tin-plated steel. Circuit boards are also a possibility. I've seen a few where 'fingers' are cut along the edge and then the fingers interlock for improved rigidity. Kind of like a dovetail joint in wood.So far, I'm leaning towards tin-plated steel boxes I found on Aliexpress. They cost less than C$2 each for 5 boxes. Oddly enough, they don't seem to be available in that size without the paint so I might strip the paint to ensure a good RF connection between the box and the top.If you're interested, here's the boxes I'm looking at. There are lots of different sizes and shapes available on Aliexpress. Most are smaller and cheaper than these.https://www.aliexpress.com/item/1005002392365130.htmlEd

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 01, 2021, 03:29:13 am
content: Well I'm as surprised as you at the price of these things. They're just a "fence" that you bend and a select a cover to go with it.Have you also considered going to a 4 layer board with ground planes on the outside and all connections on the inside? Absent any details of your circuit I'm just throwing out ideas.Also you could just order ~<0.020" copper-clad PCB material and cut it with shears. It's flexible and you can easily solder it.

author: edpalmer42
author_rank: Super Contributor
timestamp: November 01, 2021, 04:08:15 am
content: I'm expecting that there will be a *LOT* of mods to this circuit. Claiming to 'design' it is a stretch. More like hack it until it works. So a 4 layer board clearly won't work. The first, and probably last, version will be dead-bug style. That sounds bad, but dead-bug actually works quite well for RF circuits. I'm using a circuit that I built a couple of years ago. Without trying very hard it has noise floor measurements in the low e-11 range.I don't know if you're into time-nuttery ( if not, you're lucky!), but I'm making my version of a DMTD (Dual Mixer Time Difference) system to measure the performance of high-quality frequency references. The first version of this circuit gave noise floor measurements in the low e-13 range. At levels like this, it seems like you not only need bulletproof circuits, but you must think positive thoughts during the measurement runs !These shields will be used to isolate channels from each other to prevent crosstalk within the instrument. How much shielding do I need? All of it!!Ed

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 01, 2021, 04:16:00 am
content: Well then why not something like this?https://www.ebay.ca/itm/152731240781I don't think anodized aluminum makes a good contact to itself and slots radiate, so I'd sand down the edges and jam some sort of EMI gasket woven metal mesh in there.

author: edpalmer42
author_rank: Super Contributor
timestamp: November 01, 2021, 04:28:42 am
content: Yes, I'll be using something like that for the main enclosure - I already have that part. The shields we're discussing will go inside the main enclosure to isolate the channels from each other.Ed

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 01, 2021, 04:42:01 am
content: The drone world maybe?https://hobbyking.com/en_us/tbs-core-shield-for-discovery-fpv-multirotor.html?queryID=4348d470773cf4285df6a2678afb0a8e&objectID=44067&indexName=hbk_live_products_analyticsI have no clue what this thing is for but it might loosen up your search filters to look elsewhere...

author: mon2
author_rank: Frequent Contributor
timestamp: November 01, 2021, 07:01:10 am
content: US $50.00 | Factory Custom Made High Precision Pcb Board Emi Rfi Rf Metal Shielding Case rf shieldhttps://a.aliexpress.com/_mrzpuFg

author: EPAIII
author_rank: Super Contributor
timestamp: November 01, 2021, 08:36:45 am
content: The ones I have seen on professional equipment and consumer stuff too, have mostly been custom designed to fit a particular PCB or other circuit situation. In the past there were tube shields but I doubt that any are being made today or if they are, they are custom. Often times different sections of a PCB are isolated with a simple, flat fence that is soldered to the ground plane with tabs - but buss wire could be used.What I would suggest is DIY. You don't even have to buy much, just cut up tin cans and they can be soldered together so assembly is easy too. You may want to buy some tools for cutting the shapes. The HVAC trade uses tools to cut shapes for custom air ducts. There are inside corner tools, notching tools, hole punches, edge rollers, etc. They even make tools that can create a corrugated edge so one piece of duct fits inside another for a joint and tools for an offset edge which is also handy for slip fits. I keep a small collection of these tools in my shop and they are often handy.And if you want to find someone to make them for you, people who do duct work may be one source. A large city may have other shops which can do sheet metal work.Another source may be your grocery store. Sometimes things like mints and candy are packaged in tin containers. These can be two piece containers where the lid is a friction fit on the bottom. Some work with tin snips could yield a box with a removable cover. You could use paint remover to take off the finish so there is electrical contact between them.

author: EPAIII
author_rank: Super Contributor
timestamp: November 01, 2021, 08:47:16 am
content: Another thought is steel chassis boxes. Aluminum is the most popular metal for most inexpensive project boxes and chassis, but people like Bud, Hammond, and others do make them from steel. They will be heavier than what you are probably thinking about, but you can probably get them in a variety of sizes. Price should be mid-range. Or, it was the last time I looked. But you will still need to fabricate a means of mounting them to a PCB if that is where you are going.Aluminum would provide electrostatic shielding, but you would need to fasten it to a PCB with screws.And then, many manufacturers of modern equipment use conductive paint on plastic for shielding. That certainly opens up a lot of possibilities.Another thought is the use of metal foil attached to a cover made of plastic or some other insulating material. You can purchase heavy duty aluminum foil at the grocery (barbecue section) or get other metal foils from commercial metal suppliers.https://www.google.com/search?client=firefox-b-1-d&q=stsainless+steel+foilHow about 3D printing the shape you need and then applying conductive paint or metal foil to it either inside or outside.I can't stop my mind from finding more ways to do this. I may not be able to sleep tonight with all the ideas.

author: Sprock
author_rank: Contributor
timestamp: November 01, 2021, 08:50:02 am
content: Hello Edused Schubert Cases for rf stuff in early days.For quick and dirty one can use tin can.http://www.schubert-gehaeuse.de/weissblechgehaeuse.htmlgood luckSprock

author: geggi1
author_rank: Frequent Contributor
timestamp: November 01, 2021, 09:32:57 am
content: Get a sheet of 0,3 mm or 0,4 mm copper. Can be cut with a cheep industrial scissor.Make a drawing of your shield-can in scale 1:1 (un-folded) and glue the drawing to the copper sheet.Cut along the cut lines and bend along the bend lines.The bending tool can be as simple as some wooden blocks and a few C clamps or a small vice

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 01, 2021, 06:26:16 pm
content: 0.3mm thick copper seems excessive and very expensive?https://www.leevalley.com/en-ca/shop/tools/supplies/project-materials/40946-brass-shim-stockThis stuff is great, I used it for patches but just realized it does come in rolls. Quite thin stuff like 1-2 mils is perfectly fine, easy to cut, shaped by hand, easy to solder.Any decent hardware store should have some. Like, probably not Home Depot but Rona in Canada does.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: November 01, 2021, 06:58:39 pm
content: While it might not be affordable, I have to contribute a word of caution: Aluminium, even if not anodized, does not make proper contact to anything due to the oxide layer forming. Conductive passivation, or if not bound to ROHs, the wondergful ALODINE process is the only way to get a stable conductingsurface from aluminium.We use inter-channel shielding which is milled from Aluminium and conductively passivated, with 0.5mm lids of the same type.

author: nfmax
author_rank: Super Contributor
timestamp: November 01, 2021, 07:08:57 pm
content: A long time ago, we used a company in Weymouth (UK) to make some custom shields for a small-batch product. They are still going, and advertise a range of custom shielding cans as well:https://www.tecan.co.ukJust don't expect Chinese prices!

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 01, 2021, 07:40:35 pm
content: https://www.ebay.ca/itm/162018379450?epid=1412356947&hash=item25b90c46ba:g:tnAAAOSw4NFgU8ZmMaybe a sheet of adhesive backed copper foil. Cut a box pattern with scissors, solder to itself, instant kludgy box.

author: coppercone2
author_rank: Super Contributor
timestamp: November 01, 2021, 10:56:12 pm
content: Quote from: Neomys Sapiens on November 01, 2021, 06:58:39 pmwhat alodine do you use? I just got the standard commonly available one (1201) for screwing around but when I was researching contact resistances, it seems that one of the alodine variants outperforms the other ones. Does not seem to be available.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 02, 2021, 01:32:32 pm
content: I think that's called Iridite in North America. It also comes in clear.

author: edpalmer42
author_rank: Super Contributor
timestamp: November 02, 2021, 05:57:52 pm
content: I had no idea that my simple question would generate so much interest. Almost 700 views in less than 2 days!Lots of good alternatives here for lots of situations. For me, I think that the metal box from Aliexpress is the way to go. Spending the time & effort to make my own is hard to justify when a box costs less than $2. I can also guarantee that the $2 box will lookmuchbetter than anything I could build!But, based on the number of views, I think that this topic will help out a lot of makers. Thanks to everyone who contributed.Ed

author: TimFox
author_rank: Super Contributor
timestamp: November 02, 2021, 07:03:35 pm
content: Back in my MRI days, we had RF shields in reasonable quantities made by Fotofab in Chicago fotofab.com.They used photo etching to make custom flat parts (including mounting tabs) that we folded up (like an open box) and soldered to PCBs.We needed non-magnetic materials, and we used either brass or Be-Cu, sometimes tin-plated.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 02, 2021, 07:36:54 pm
content: Well if a candy tin is good enough, surely you can buy Altoids near you.https://upload.wikimedia.org/wikipedia/commons/thumb/d/dc/Altoid_and_tin.JPG/220px-Altoid_and_tin.JPG

author: Andreas
author_rank: Super Contributor
timestamp: November 02, 2021, 08:07:17 pm
content: Hello,what about TEKO 3710 or TEKO 4020?https://www.reichelt.de/stahlblechgehaeuse-54-x-50-x-19-mm-silber-teko-3710-p34042.html?&nbc=1on the other side if you need it custom specific:every PCB manufacturer (who can do SMD stencils) should be able to etch/laser any size of housing from brass or nickel silver.Some examples of home made self etched parts (from photo sensitive coated brass sheets available from BUNGARD).https://www.conrad.de/de/p/bungard-271003-145-messing-blech-fotobeschichtet-negativ-messing-l-x-b-x-h-215-x-145-x-0-3-mm-inhalt-1-st-529060.htmlwith best regardsAndreas

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: November 03, 2021, 06:33:34 pm
content: Quote from: coppercone2 on November 01, 2021, 10:56:12 pmAlodine 1200S according to a note. (MIL-DTL-81706A Class3) But it was always done by some surface treatment shop.