Dear Mr. Schmidt,
I would like to comment on one aspect which I think is completely different from what you described. You wrote:
" 4.) Maybe one of the most simple technical problems will be the most
important system problem: we have to switch over just at one moment, e.g. at
the same moment we need all the components with lead free finish and the
board(s) with leadfree finish and all the processes (reflow, wave and
rework) to be defined and approved. We either have to waste the old
components from the stock or organize the complete stock of lead containing
components to run out at the same time, refill the stock with the new
components, not to have any mixture and then to switch over - good luck !!
The most problematic seems to be the component availability (think of a
horrible market today): as wide as the spread of component funtionalities is
the spread of manufacturers - from the large
semiconductor/passives-producers to small specialists. How can they/we
handle this. "
Sometime during the sixties, Sweden went from driving on the left to driving on the right side of the road. They had one traffic-free night with a lot of hard work of a big crew of people and the next morning everybody drove on the right. This
illustrates that, for some situations, this can be done.
However, I think that we will never be able to do something similar in electronics. We will be facing a period of a "mixed economy" with lead containing and lead-free components, boards and solders. That implies a boundary condition that all these parts
and materials should be backward and forward compatible.
There is one more reason for this. Many systems have to be maintained for decades (telephone exchanges, medical equipment, airospace and defence systems, etceteras). In order to enable this, components and modules have to be stocked for such long
periods, simply because the lifecycle of components is limited. (E.g. probably, not a single IC type from 20 years ago is in production any more so, they should be stocked instead.) After many years, they still have to be mountable, e.i. lead containing
parts will have to be soldered with lead-free solder into a lead containing piece of equipment.
In conclusion:
We can only handle this by developing soldering systems with backward and forward compatibility.
Best regards,
Erik
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Erik E. de Kluizenaar
Philips CFT - Electronic Packaging & Joining (EP&J)
Building SAQ-p, p/o box 218, 5600 MD Eindhoven - The Netherlands
Tel/Fax: (+31 40 27) 36679/36815; E:mail [log in to unmask]
PHILIPS worldwide homepage: http://www.philips.com
Internal PHILIPS only: http://pww.cft.philips.com/cfteurope/electronics/elpajo/index.htm
-----------------------------------------------------------------------------------------------------------------------------------
[log in to unmask]@[log in to unmask] on 2000/10/24 10:16:08 AM
Please respond to [log in to unmask]@SMTP
Sent by: [log in to unmask]
To: [log in to unmask]@SMTP
cc:
Subject: [LF] we need a system solution for 'leadfree'
Classification:
Dear colleagues,
I've just looked through all the mails from the forum of the last months and
learned a lot on "what's happening inside the solder joint" and "politics
are ..." but I like to remind you all to the points mentioned in some
writings of H.J. Bauer and D. Suraski (send in April, see annex):
The major point is that we need a system solution and not a solution simply
for one point !!!
Let me point out some facts:
1.) There are a lot of boards (e.g. telecom) containing a collection of very
different components: from small ceramic resistors to large PE-capacitors,
tantalum-caps and even transformers - all those just adjacent to any of the
other ones. Not all boards are memory boards using a few different types of
integrated circuits and some ceramic caps and resistor chips. Someone wrote
of using more IR-heating to solve the temperature problems or to select
shiny cans to prevent components from overheating. On the other hand the
technical evolution presented "forced air convection" to enable
manufacturers to use a component mix like mentioned before. I don't think
that we are able to step back. And if you'll present new restrictions to the
layouters: you won't find any new friend there and lose the old ones !
2.) Reliability is a severe problem with different aspects: the producer of
things like "discman", "minidiskplayer" etc need that all their products
must have full functionality when delivered to the customer. But does
someone think of a diskman working for 10 years at 24h a day at any day of
the year ?????? But telecom bords must !!!! Military products must stand
the same time but not working continously at (nearly) constant temperatures
but switching on/off within a large temp-range and meeting their
specification from < 0 degree C to > 50 degree C. What's about reliability
then ??
3.) As not all the components are available (see 1.) as SMDs the combination
of wave- and reflow-soldering makes still sense. So we not only need a
solution for reflow but as well for wave soldering. And from a manufacturer
of soldering systems (SEHO) I've learned that they still have the problem
that their machines will stand the "standard-lead-free-soldes" for only some
month.
4.) Maybe one of the most simple technical problems will be the most
important system problem: we have to switch over just at one moment, e.g. at
the same moment we need all the components with lead free finish and the
board(s) with leadfree finish and all the processes (reflow, wave and
rework) to be defined and approved. We either have to waste the old
components from the stock or organize the complete stock of lead containing
components to run out at the same time, refill the stock with the new
components, not to have any mixture and then to switch over - good luck !!
The most problematic seems to be the component availability (think of a
horrible market today): as wide as the spread of component funtionalities is
the spread of manufacturers - from the large
semiconductor/passives-producers to small specialists. How can they/we
handle this.
Sorry it was a long list but I think we habe to regard system solutions -
otherwise we will have more problems than we can handle.
I'm waiting for your response and discussion !!!!
Regards
W.-D. Schmidt
(Product-Engineer)
SEL Defense Systems
PO-Box 1760
D-75117 Pforzheim
Tel.: +49 7231 15 3386
Fax: +49 7231 15 3390
eMail: [log in to unmask]
> -----Ursprüngliche Nachricht-----
> Von: <Hans Juergen Bauer> [SMTP:[log in to unmask]]
> Gesendet am: Montag, 17. April 2000 14:41
> An: [log in to unmask]
> Betreff: [LF] AW: Re: [LF] DTI update report
>
> Hello Mr.Dsuraski,
>
> thanks for Your opinion, You are the second, who is thinking after the
> components. It may be, that "whisker, solidus, liquidus, several kinds
> of alloys" are of interest for metallurgicians, but if process
> temperatures
> will rise 30deg to 40deg above the todays existing for tin lead alloys,
> we must bury some component families:
> Polyester Caps
> Polypropylen Caps
> Aluminium Electrolytics, some will explode, some will loose a lot of their
> useful lifetime.
> Tantalum chips,
> Ceramic multilayer with reduced reliability.
> Most of todays electromechanic components are unable to withstands higher
> temperatures.
> (semiconductors I don´t know, it´s not my profession)
>
> Who is interested to buy a car with ABS and Airbag electronics, produced
> with such processes?
>
>
> Waiting for answers,
>
> Hans Juergen Bauer
>
> ----------
> Von: dsuraski / unix ([log in to unmask])
> An: [log in to unmask]
> Betreff: Re: [LF] DTI update report
> Datum: Montag, 17. April 2000 13:53
>
> Perhaps it's naiveté, but it seems to me that the major impediment in the
> lead-free issue is indeed related to components- but not their plating.
> Rather, it seems that the questionable reliability of many components
> when
> exposed to the higher reflow temperatures of lead-free solders remains
> the
> biggest issue. We know that there are some solutions regarding the
> plating
> issue, even if these are more expensive and more difficult to process.
> But
> what can we do to assure that components are not degraded/destroyed by
> reflow peak temps of 240-260C? Is anyone trying to rate their components
> to these temperatures en masse?
>
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