Why Lead-free?
Environmental improvement (reduction or elimination of the potential
hazardous effects from lead poisoning). ST promotes lead-free manufacturing,
which is mandated by legislation and supported by strong market demand.
On 27.01.2003 the European Parliament and the council adopted the
directives:
2002/95/EC on the Restriction of the use of certain Hazardous Substances
in electrical and electronic equipment ("RoHS")
What is Ecopack?
Ecopack is the registered trade-mark of ST for its component development
and programs implementation for solutions leading to environment friendly
packaging and packing materials. Ecopack products are Lead-free and
RoHS compliant. This means mainly lead (Pb) will be replaced (less
than 0.1% lead in any base material).
Base materials are for example the surface finish layer, or solder
balls. ST is introducing Ecopack products with the capability to perform
board assembly with Pb-free solder.
RoHS is considering exceptions, when the alternative to Pb-based technology
is not available, like in the case of high Pb-content (>85%) soft
solder die attach of power devices. Also in this case, the products
are called Pb-free ? which essentially means RoHS compliant.
What is the definition of Pb-free?
Content less than 1000 ppm Pb by weight of the base material. Exceptions
exist, as explained above.
Do ST products contain Lead today?
We are now ensuring all our products are being converted to
lead-free materials. Exceptions exist, as explained above. Of course
most packages still contain traces of lead: small amounts well below
legislative requirements. Conventional Sn/Pb soldering contributes
significantly to overall lead content of electronic equipment, together
with any lead present in the components themselves.
Who is the contact at ST for "Ecopack product"?
The first contact for all questions about Ecopack Products
is your sales contact.
When are "Ecopack" packages available?
ST has already the Ecopack technology for all products available
today. Samples can be ordered through your sales contact.
What is Green Component in ST?
Green is used to describe the trend to eliminate Halogenated
Flame Retardant in electronic components. Halogen free (bromine free),
including TBBA and Sb2O3, materials are not
a RoHS requirement but a trend in molding compounds to get better
performance. ST is evaluating systematically such molding compounds
to improve package robustness when necessary.
Technical
Are Ecopack ST? devices compatible with conventional
(Sn/Pb solder paste) soldering processes?
Yes. For many years our products have been suitable for the
higher temperature profiles required by most lead-free soldering processes.
Full forward / backward compatibility is ensured because all lead-free
devices have either pure tin or NiPdAu plating.
Note: one exception is the BGA (reflow temperature too low for melting
SnAgCu, SAC, solderballs).
Does pure tin plating have any effect on external/
internal dimensions or mechanical and electrical behavior?
All dimensions and both mechanical and electrical behavior
are unaffected. Also, no change in the distribution of electrical
parameters has been detected.
Do higher soldering temperatures have any negative
impact on the moisture sensitivity level (MSL)?
In most cases the MSL is not impacted by the higher soldering
temperature. However, since some rare exceptions exist, please ask
to your sales contact for more information.
Do Pb-free products have any impact on shelf
life?
No. Guaranteed shelf life remains the same as for current
SnPb products, except for the exceptions mentioned referring to MSL
level.
What are ST? Ecopack solutions?
a) NiPdAu pre-plated
b) 100% Sn (electroplated : Matt Sn + postbake or solder dipped)
c) SnAg4.0Cu0.5 (SAC) for BGA packages
Why is pure tin used?
Through many years experience ST has found pure tin to be
the proven, logical choice for coating package leads / terminals,
enabling ideal drop-in replacements for devices using lead-alloy plating
What measures are taken by ST to prevent whisker
growth on products?
Along with thorough test procedures and extended studies performed
together with Infineon, Philips, Freescale, the following measures
are introduced into the production process:
We have investigated whisker behavior of our products for more than two
years and no anomalous whisker growth has been detected in the testing
conditions reported in enclosed application note.
Does "Ecopack" affect the product reliability or
functionality?
Ecopack Products are designed and qualified for the same or better
performance as today (with respect to lead-free board assembly process).
The conversion to Ecopack products does not change the functionality.
Is the guaranteed maximum temperature in soldering
profile is measured at pins or at package?
The MSL temperature is dealing with top-package body temperature
(so is the soldering temperature resistance). Solder joint temperature
is not so different but is PC board dependant and more difficult to be
reproduced.
Does the use of Ecopack components impact the soldering
process?
Soldering process is defined by the solder paste characteristics
(melting point) and the themal capacitance of the board. Component has
almost no impact on the process. |
