1. Regarding point one, it is clear who is responsible for identifying
components to be used for lead-free product. It is defined by the contract.
The owner of the design, be it the CM or in most cases the customer, is
responsible for designing the board and calling out the corresponding BOM.
The BOM is a restriction of what components can or can not be used, so
whomever builds the BOM is responsible for determining the component design
requirements thus determining vendor part numbers, and hence takes
responsibility for whether it will be lead-free compatible or not. In many
cases, the customer may design the board and call out the BOM, but allow the
CM to build the AVL. In that case, the CM is responsible to make sure all
alternate components meet the BOM called out design requirements. In all
cases, the customer is responsible for determining the reliability of their
product, unless they specifically contract the manufacture to do that.
However, if the CM begins using lead-free solder paste and reflow profiles
on product that is NOT customer requested for lead-free, they assume all
liability.
2. Component manufactures are responsible for making sure their product is
qualified for lead-free processes and marketing them for such, i.e. with new
part numbers, new moisture sensitivity levels, or new design descriptions.
If a component is used that is not qualified by the component manufacture as
lead-free ready, then liability rests squarely on the shoulders of the BOM
owner.(see point one).
3. Keeping track of lead-free vs. non-lead-free will be virtually
transparent since that will be controlled by the BOM. Lead-free parts will
have different part numbers than non-lead-free parts. The only thing to
keep straight is the process work instruction for each "product number" that
will call out different reflow profile recipes and solder paste part
numbers.
4. As a CM, some customers demand water soluble paste, some demand no-clean
paste, while most just don't care. Either way, you'll have to work out the
logistics and processes to keep multiple pastes from being mixed regardless
of lead-free.
5. My experiences with lead-free, the boards did not sag any more than they
do normally anyway and lead free joints show up just fine on the X-ray. In
fact, no modifications of automated X-ray (5-DX) vision algorithms are
needed. AOI works just fine with lead-free as well, but you may have to
re-calibrate your visual inspection operators.
6. Cost has been analyzed and it is not justified. The cost to benefit is
negative. The toxicity of Silver is as much a moot point as the toxicity of
Lead. And the guy who dumps his battery on the side of the road is an idiot
because he can get paid to recycle the battery (I made $8 just the two days
ago when I took mine in).
Really, if you have a problem with lead-free, let your Senator know. The
only ones whispering in the ears of congress persons are special interest
groups like environmentalist.
Ryan Grant
-----Original Message-----
From: Joe Fjelstad [mailto:[log in to unmask]]
Sent: Tuesday, November 05, 2002 12:25 PM
To: [log in to unmask]
Subject: [TN] Managing the conversion to lead-free
Dear industry colleagues,
Not infrequently off line e-mail arrives which is often both illuminating
and thought provoking. The following material is from one such message, in
this case, from a contract manufacturer who has some posed some technical
and logistical questions regarding conversion to lead-free that are likely
being faced by most if not all contract assemblers.
I received permission from them to post the following for general comment.
Please consider this a "from the trenches" request from an individual on the
front lines.
Comments, suggestions or ideas relative to the points made should preferably
be posted on the forum, however, if you prefer, I can take your comments off
line and forward them to the sender.
Thanks in advance for sharing your thoughts/comments.
Kind regards to all,
Joe
"1. As a contract manufacturer, we have many customers with many designs,
and many different component part numbers. It is not clear who will be
responsible for identifying which components can handle the longer hotter
reflow cycles or wave process. I am sure the burden will be shared as some
customers will request the change and others may accept the change.
2. I am not as concerned about the bare board materials as I am about the
individual components. For each component, the reliability and
functionality needs to be reviewed -- especially components that are
Moisture Sensitive Devices as those have been qualified under the 63/37
reflow melting temperatures.
3. Identifying, Categorizing, and Separating inventories for customers with
lead-free vs. not lead free is going to be a logistical nightmare. Keep in
mind, if there is no legislation in the US and some of our customers are
happy with the current alloy they will have no reason to change and CM's
will need to keep inventories straight.
4. Many companies have a difficult time keeping No-Clean and Water Soluble
chemistries from being mixed -- Imagine if we need to keep Lead-Free
No-Clean and Lead-Free Water Soluble chemistries away from the Leaded
No-Clean and Water Solubles?
5. Equipment -- A second Wave machine will be needed, center support rails
on the reflow ovens will be needed to support the PCB's that sag under
higher heat, increased machine maintenance will be needed, and imagine how
the cost of electricity will go up along with the cost of increased AC!
What about Nitrogen -- We'll probably need to add that with the board
finishes and higher temps. How will X-ray work without Lead? How will
Vision systems work as the reflectivity of the solder joints change?
This just touches the tip of the iceberg.
I suppose what confuses me the most is the cost. Is the cost of this all
justified? Has anyone done a cost/benefit analysis?
I am also confused when I hear that Silver is one of the elements used in
one of the more promising alloys. Is the risk and high toxicity level
associated with mining and refining silver far less than the toxicity of the
lead that ends back up in the ground (where it started in the first place?)
And what about the guy who dumps his battery on the side of the road so he
doesn't have to pay $5 to get rid of it properly?
Well, I suppose that's enough for one night. It was kind of fun to be on
the soap box for a few minutes and relieve some of the stress about what
might become inevitable."
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