RoHS and Leaded
william chan
Posts: 1,326
What's the difference between the RoHS chips and the Leaded chips for us users?
Does RoHS chips require different soldering techniques or different solder material?
Are they the same price?
Does RoHS chips require different soldering techniques or different solder material?
Are they the same price?
Comments
They require lead-free solder and a bit of a higher temperature for soldering. It seems that this is not a big deal in terms of the SX packaging as the epoxy covering is quite durable.
I guess for Asia, RoHS won't become an issue until sometime later. Being the manufacturing hub of most of these things, they probably prefer to lag behind in compliance as they generally have backlogs of old production runs that are perfectly useful, but not leading edge technology. They also have quite a bit of the older manufacturing technology that remains useful and profitable.
Economic realities are not quite the same as new regulations.
It is quite convienent for the Asian manufactures to dump their out of date and less sucessful products in Asia. Consumers are often less well informed as the language barrier keeps them a bit behind in understanding high tech innovations. Still, they have inventors and educators that do lead the world, but these are isolated individuals, not the buying public.
I don't think you will see an immedate disappearce of lead solder and all that is related. In some ways, the new solder might be neater. Apparently it doesn't pile up as high, so you use less and your boards are not as likely to have solder bridges.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
In other words, if I have an RoHS part, but am not building an RoHS compliant assembly, do I still need to use lead free solder with the part?
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
John R.
8 + 8 = 10
Yes, at least this is the case for the SX chips. However, this is a complex issue that in my opinion requires some experimentation in your manufacturing line. The confusion stems from the manufacturers. First, some suppliers will transition to lead-free (RoHS, I use the terms interchangeably) and use the same part number. All of the sudden you will receive lead-free parts. Perhaps there's a new laser-etching on the chip; perhaps there is not. Other suppliers will tell you to order a different SKU for RoHS. We've observed a lot of inconsistency in the way this is handled. For example, in the case of a BASIC Stamp, we're switching them to RoHS-compliant but keeping the stock code BS2-IC. The reason is that if the BASIC Stamp is used as a finish good it is likely thrown in a socket rather than mounted to a PCB in a lead-free line. But in the case of the SX, we have new part numbers for RoHS parts.
This is the first point you need to pay attention to when ordering parts.
The second detail which requires more careful attention is what the manufacturer says about their RoHS-compliant parts. Some manufacturers have told us that their RoHS parts can be reflowed in a standard leaded assembly line with 235C temperature. Others, such as the packaging company we use for the SX (Greatek), tells us that you can not reflow their RoHS parts in a leaded process at 235C because the parts will fall off of the PCB. Instead, they suggest a lead-free solder and 255C reflow temperature.
That's the second point which requires special consideration.
The third thing I'd tell you is that you shouldn't be paying inflated prices for the RoHS version of a part you formerly purchased in a leaded package. Initially, many suppliers indicated that RoHS would have an additional fee of xx cents. Now, I'm seeing that prices are remaining the same (or very close) to the leaded counterparts.
The result of all of this is that you may have (as we do) double the inventory to build any given product while you make this transition. If you look at our inventory, not only is it increasing at a great rate which causes accountants to shake their finger, you'll see that we have leaded and RoHS side-by-side. This is what it takes. The new SX chips are a good example - we have twice the inventory we'd normally have since customers still require leaded parts.
The final consideration I'd suggest you investigate is the reflow oven equipment. Our current reflow oven barely reaches the 255C temperature required for the RoHS parts. On my recent trip to Asia, many of the manufacturers have bought new ovens (from Heller, a German company) just for RoHS assembly lines. I think the only winner in this conversion so far is Heller, but it's supposed to be good for the environment over the long term.
You should also note that although you may not sell to Europe, RoHS (or at least the lead-free part) will become necessary if you sell in the U.S. California has passed a law very similar to RoHS regulations which will cause all U.S. destined product to comply with California laws since our lovely state is a probable shipping destination for almost anything. You can see how California influences product contents right now by walking into a RadioShack. Their leaded solder (if they still have it) says something to the effect "California has determined that lead is associated with health effects. . . so be careful".
I believe you will also see lead times from your favorite manufacturing suppliers increase while this issue is taken more seriously. I know that for Parallax it's a difficult, albeit procedural transition that we're doing to meet the RoHS rules.
And really, I know very little about this whole RoHS thing. . . don't take my input too seriously without doing your own research.
Ken Gracey
Parallax, Inc.
Why would the parts fall off the PCB? The RoHS SX chip is heavier? : )
What about when using hand soldering, can we use leaded solder on a RoHS SX?
What is the difference in packaging for the SX?
Is the epoxy stronger? Are the chip legs made of a different alloy?
Both package types are plastic. The difference is in the bonding wire and pins, which use a different type of metal for RoHS.
Ken Gracey
For the hobbyist,
RoHS devices may be hand soldered with lower temperature lead based solders. Nonetheless, there may need to be some adjustment with technique [noparse][[/noparse]probably flux and actual temperature] in order to properly bond.
Of course such devices are intended for personal use and have no export/import implication.
Reflow presents substantial change in temperature and using RoHS approved solder may actually simplify the whole process as RoHS was never intended for mixed use.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan