Design Challenges: Avoiding the Pitfalls, winning the game - Xilinx

Designer Challenges
for Pb-Free and
Green Products
Ease the transition to green solutions with Xilinx Pb-free products.
by Paula Ungs
Sr. Marketing Manager
Xilinx, Inc.
paula.ungs@xilinx.com
Many challenges are associated with
designing products that are not only safer
for the environment but meet the legislative
and OEM requirements that are being
adopted around the world. To ensure success,
you must understand the global
requirements and deadlines for the removal
of hazardous substances from electronic
products. At a more practical level, you
must understand how Pb-free devices
impact board design. Xilinx ® understands
these challenges and offers a strategy to ease
the transition to Pb-free and environmentally
friendly products.
Global Environmental Requirements
To develop products that can be shipped
globally, you must comply with global
requirements and deadlines for the
removal of Pb and other hazardous substances
from electronic products. As
shown in Figure 1, the most eminent
requirement is the European Union (EU)
directive for the restriction of the use of
certain hazardous substances (RoHS). This
directive bans shipments of electronic
products into the EU after July 1, 2006
that do not comply with the directive’s
restriction on Pb, mercury, cadmium,
hexavalent chromium, PBB, and PBDE
flame retardants.
Japan recognizes RoHS and also
enforces their own green initiatives, driven
by recycling/reuse laws in their country.
China recently announced plans to adopt
legislation that will be more strict than the
RoHS legislation – banning, rather than
restricting, the named substances by the
same July 1, 2006 timeframe. Individual
states in the U.S. are also considering bans
on the same list of materials – and potentially
others.
Pb-Free in Board Designs
How do Pb-free solutions impact board
designs? As a rule of thumb, Pb is distributed
in electronics in the solder (75%),
board (20%), and components (5%), so
you must understand the implications to
the overall solution. “Green” components
in the industry feature new material sets
that require changes to solder materials
and processes, which in turn affect board
selection. The good news is that most Pbfree
packages have the same form, fit, and
function as standard packages; no special
board layout considerations are required
from the component side.
Pb-free lead-frame packages (for example,
PQG and TQG) that use matte tin
plating on the leads are of little concern,
since they are considered “backward compatible”
to traditional SnPb manufacturing
processes. However, many Pb-free BGA
package solutions in the industry use a
SnAgCu solder ball material that is not
backward compatible with traditional
manufacturing processes. The SnAgCu
material requires higher peak reflow temperatures
than those specified for standard
packages. This situation makes it difficult
for designers to mix Pb-free and standard
components on the same board. So the
decision must be made up-front as to
whether the board will be Pb-free or not.
The BOM for Green Products
Crafting the bill of material (BOM) can be
difficult when designing Pb-free solutions.
Pb-free devices cannot always be mixed
with standard devices on the same board
because of differences in the manufacturing
process. Therefore, you need to know if a
given device is Pb-free or standard when
including it in a board design. What makes
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