Post by thread:[EE] ROHS compliancy

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Mon, Jan 28, 2008 at 09:39:34AM +0200, Dumitru Stama wrote: > Hi guys, > I was wondering if online PCB-makers are usually RoHS compliant. > I am using components which are compliant, solder without Pb, > plastic container which contains no forbidden substances but > the real question comes when i get to the PCB part. > Is it the solder mask which is usually not compatible with > ROHS constraints ? No, it's the lead finish on the traces themselves. RoHS versions use alternatives such as tin or electroplated silver or gold. Solder mask is just an epoxy-based coating, fairly harmless. You should check each one if it really matters, but it's becoming increasingly common for them to be RoHS complient. Advanced Circuits is for instance: http://www.advancedcircuits.com/index.php?load=content&page_id=17 - -- http://petertodd.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFHnY8s3bMhDbI9xWQRAmaWAJ4kACF96uMhnrKiUYh90/MbN1vXEgCggpIS XyUm7kmB+OVb9eutF++HaBY= =qEzH -----END PGP SIGNATURE-----

There are several components in a PCB that could be RoHS non-compliant. You can't really focus on one thing, say plating, and then assume that if the PCB has the correct plating then it's RoHS. Most manufacturers that I've dealt with can produce RoHS compliant PCBs, but you need to specify RoHS compliance when you order just as with any other component. -Adam On 1/28/08, Dumitru Stama <spam_OUTspanacTakeThisOuTgmail.com> wrote: > Hi guys, > I was wondering if online PCB-makers are usually RoHS compliant. > I am using components which are compliant, solder without Pb, > plastic container which contains no forbidden substances but > the real question comes when i get to the PCB part. > Is it the solder mask which is usually not compatible with > ROHS constraints ? > Dumitru > -

M. Adam Davis wrote: > There are several components in a PCB that could be RoHS > non-compliant. You can't really focus on one thing, say plating, and > then assume that if the PCB has the correct plating then it's RoHS. > > Most manufacturers that I've dealt with can produce RoHS compliant > PCBs, but you need to specify RoHS compliance when you order just as > with any other component. > > -Adam > > After some rather worrisome reports from NASA, we have decided as a company to NOT use lead-free solder and fluxes on my clients' products. We haven't regretted it, either. --Bob

> After some rather worrisome reports from NASA, we have > decided as a > company to NOT > use lead-free solder and fluxes on my clients' products. > We haven't > regretted it, either. Non -ROHS compliant is not an option is some cases - such as when selling in Europe. At the risk of over generalising I'll suggest that ROHS is largely not a vast issue for devices with "normal" clearances dimensions and sizes. Issues such as solderability and inspection / testing need to be relearned at any scale of construction. But it's when you get down to sub sub mm pad clearances and say 0402 type component sizes that things start to matter. Also, products with much longer than usual design lifetimes are liable to be at risk at almost any construction dimensions. Tin whisker growth can become a crippling issue in such cases. Russell

Apptech wrote: {Quote hidden}>> After some rather worrisome reports from NASA, we have >> decided as a >> company to NOT >> use lead-free solder and fluxes on my clients' products. >> We haven't >> regretted it, either. >> > > Non -ROHS compliant is not an option is some cases - such as > when selling in Europe. > > At the risk of over generalising I'll suggest that ROHS is > largely not a vast issue for devices with "normal" > clearances dimensions and sizes. Issues such as > solderability and inspection / testing need to be relearned > at any scale of construction. But it's when you get down to > sub sub mm pad clearances and say 0402 type component sizes > that things start to matter. > > Also, products with much longer than usual design lifetimes > are liable to be at risk at almost any construction > dimensions. > > Tin whisker growth can become a crippling issue in such > cases. > > > > Russell > > Our case is that we design safety equipment used by power companies, mostly US and Canada. Our equipment really, really MUST be able to operate properly ALL the time. Tin whiskers are just something else to worry about. Our equipment is used to shut down and/or service overloaded breakers (8,000-10,000 AMPS at moderate voltages). A "hazmat" suit is not normally required to be worn when using our stuff. --Bob A

At 04:02 PM 1/28/2008, Apptech wrote: > > Our equipment is used to shut down and/or service > > overloaded breakers (8,000-10,000 AMPS at > > moderate voltages). > >It would have to be a pretty massive tin whisker to bother >you then. Not even close. Yeah, I saw the smiley. But I was part of the team that diagnosed a major reliability problem at a coal-fired power generating station and it was I who discovered the root cause: tin whisker growth on a wire-wrap backplane controlling one of the three generators. The company wound up replacing the entire voltage regulator and power stabilizer systems on TWO separate 400MW generators - the 2nd unit had begun exhibiting the same problems as the first. They are actually running these systems over-spec - somewhere near 450MW each. That's 900MW of generating capacity that was at risk because of these tiny tin whiskers. To give you an idea of how sensitive the problem had become: rapping the side of the rack holding those card cages was almost enough to cause the plant to trip off-line - the disturbances were that severe. Some of our customers are insisting that we NOT use lead-free technology in equipment manufactured for them until it (lead-free) has been proven reliable in the long term. Mostly utility companies and such. dwayne -- Dwayne Reid <.....dwaynerKILLspam@spam@planet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax http://www.trinity-electronics.com Custom Electronics Design and Manufacturing

Dwayne Reid wrote: > But I was part of the team that diagnosed a major reliability problem > at a coal-fired power generating station and it was I who discovered > the root cause: tin whisker growth on a wire-wrap backplane > controlling one of the three generators. > What made wire-wrapping necessary on something required to be so highly reliable? Yes, I know wirewrapping can be reliable but it seems as though through-hole PCBs are about the most reliable construction method. - Martin

On Jan 28, 2008, at 4:45 PM, Martin Klingensmith wrote: > What made wire-wrapping necessary on something required to be so > highly > reliable? Yes, I know wirewrapping can be reliable but it seems as > though through-hole PCBs are about the most reliable construction > method. Wirewrap used to be really popular for backplanes, back before buses became standardized and popular. We had a couple people who would spend time debugging DecSystem-20s (late 1970s era computer) by figuring out which wire was wrapped too tightly around a nearby pin, eventually causing the insulation to "creep" and short the signal. (This in the late 1980s, well beyond 'expected lifetime' of such a computer.) BillW

At 05:45 PM 1/28/2008, Martin Klingensmith wrote: >What made wire-wrapping necessary on something required to be so highly >reliable? Yes, I know wirewrapping can be reliable but it seems as >though through-hole PCBs are about the most reliable construction method. The PCBs were as you described. It was the backplane itself that was wire-wrapped. Sort of, that is. All of the edge connectors had long wire-wrap pins for the connections. The power rails were busses with formed pockets that were pushed onto the pins. The push-fit was obviously deemed not adequately reliable because they had been soldered in place during manufacture. Most (all?) of the leads leaving the backplane used a funky spring clip that held the wire tightly against the pin. I *think* it was the AMP Termiclip family. I'm not sure if *any* connections were actually wire-wrapped - I don't remember. Its just that the edge connectors used wire-wrap pins. It was those pins that were sprouting whiskers. Yeah - those edge-connector pins were tin-plated instead of gold-plated. Note: the contacts that mated with the PCBs were gold-plated. It was just the wire-wrap pins on the backsides of the edge connectors that weren't. Quite frankly, that was the only thing that detracted from this obviously high-quality piece of equipment. Seriously high quality: mil-spec everything: from the pots to the op-amps to the solid slug (wet) tantalum caps. Not a single conventional electrolytic cap to be found. Film caps everywhere. They had sent me a complete set of spare PCBs to examine and repair if necessary. I built simple test jigs that let me test the functionality - everything tested good. Trim pots were all OK (a real surprise!) - not noisy at all. All of the active components tested OK. Thus the trip out to the plant. dwayne -- Dwayne Reid <dwaynerKILLspamplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax http://www.trinity-electronics.com Custom Electronics Design and Manufacturing

>> After some rather worrisome reports from NASA, we have >> decided as a >> company to NOT >> use lead-free solder and fluxes on my clients' products. >> We haven't >> regretted it, either. > >Non -ROHS compliant is not an option is some cases - such >as when selling in Europe. Even in Europe, space instrumentation has an exemption from RoHS for soldering ... >Tin whisker growth can become a crippling issue in such cases. And you do not need to be in a vacuum either. The vacuum possibly accelerates the whisker growth, but is not essential.

Yes but by being in European Union i have to comply with RoHS if i want to sell some product. On Jan 29, 2008 11:27 AM, Alan B. Pearce <.....A.B.PearceKILLspam.....rl.ac.uk> wrote: > >figuring out which wire was wrapped too tightly around a nearby > >pin, eventually causing the insulation to "creep" and short the > >signal. (This in the late 1980s, well beyond 'expected lifetime' > >of such a computer.) > > So, built in obsolescence , even then ... ;) > > -

> -----Original Message----- > From: EraseMEpiclist-bouncesspam_OUTTakeThisOuTmit.edu [piclist-bouncesspam_OUTmit.edu] On Behalf {Quote hidden}> Of Apptech > Sent: 30 January 2008 12:30 > To: Microcontroller discussion list - Public. > Subject: Re: [EE] ROHS compliancy - PCBs > > > Yes but by being in European Union i have to comply with > > RoHS if i want > > to sell some product. > > Yep. > They don't care if it works as long as it's green. > > People like Swatch have, I'm told, obtained full exemption > because of the problems. > > Memory says that 0.64mm pitch is the point below which > exemptions may be granted. Memory may be wrong. There are also exemptions for high reliability equipment (such as telecoms) because the long term reliability of lead free solder etc. is not yet fully understood. Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. =======================================================================

Apptech wrote: >> ... the long term reliability of lead free solder etc. is >> not yet fully understood. >> > > Maybe not "fully". > But quite well enough to know that for reliability you don't > want it if you can avoid it. > > > Russell > > > > I wonder if its possible to use silver solder for electronics work of this kind. Or for high-rel stuff just use solid gold. Fairly low melting point and your guaranteed not to put too much of the stuff on. The scroungers would love it too ;->