RIFA caps, again - Page 1
Forum section: electronics / general

author: rdenney
author_rank: Regular Contributor
timestamp: September 25, 2025, 01:39:47 pm
content: What is the prevailing view on modern RIFA caps from Kemet for replacements in old equipment? Erik at Erik's Electronics Workbench seems to think the modern versions have corrected the material problem of older examples so that they do not crack with age. But Mr. Emperor of Test Equipment won't use anything with the RIFA brand on it, Kemet acquisition notwithstanding.I've been buying them simply because nothing else has the same lead spacing, and finding alternatives with the correct values also isn't easy. At least I'm resetting the aging clock. And it seems Digikey won't let me at X2 and Y2 failure ratings as a filter when searching through their 2.4 bazillian caps.What say the greybeards of EEVBLOG?Rick "doesn't buy caps from ebay or Amazon, especially those with critical safety ratings" Denney

author: floobydust
author_rank: Super Contributor
timestamp: September 25, 2025, 04:09:15 pm
content: PME 271 metallized-paper EMI cap announced in 1973! They were rated to 200MHz and high dV/dt rated 1,200V/usec. Rifa a Swedish company originally.I think paper beat plastic in 1973- but those days are long gone.These caps are well proven failures with age. Many theories about why they fail. I found new ones, in a parts drawer at work that had ballooned out a bit as well as the epoxy cracking. Unused, they hadn't even been through reflow/wave soldering. Some dimensional instability. Flamed Kemet in an email but no response, and the parts are still on the market.Lead spacing is non-standard:25.4mm -> use 25mm20.3mm -> use 22.5mm stuff it in there15.2mm -> use 15mm10.2mm -> use 10mmI get new film caps with longer leads "PC Pins - Long Leads" and splay them to fit. Like R46 PP or R47 or the Wurth or Epcos B32921, 922 parts.

author: TERRA Operative
author_rank: Super Contributor
timestamp: September 25, 2025, 10:35:39 pm
content: I agree with floobydust.Also, on Digikey you can search for X and Y rated caps by going to the film capacitor section and selecting the desired ratings in the 'Ratings' column.This link will get you started:https://www.digikey.jp/short/p58ttv3v

author: thm_w
author_rank: Super Contributor
timestamp: September 25, 2025, 11:41:30 pm
content: Quote from: rdenney on September 25, 2025, 01:39:47 pmThe "correct value" doesn't really matter. Anything close or a bit larger in capacitance would be fine.I don't think Rifa's are used for capacitive dropper circuits? If they are then you'd want something close to the rating.https://www.eevblog.com/forum/beginners/quality-replacement-for-rifa-x2-capacitor/

author: Swake
author_rank: Frequent Contributor
timestamp: October 03, 2025, 06:25:05 pm
content: Same here, found 'new-old-stock' classic RIFA caps in a drawer that were cracked.They are also present in mains filter modules potted in some extra epoxy and still fail in those too. All those caps failed or will fail very soon from now and RIFA never took any responsibility about it. That is a big no no for me in terms of reputation.Early on they got me with the Kemet rename. I wasn't aware and bought some stuff from that brand. Never again will they get a place from me. I cannot get over it.