Thermal cycle testing is being conducted by Boeing Phantom Works (Seattle) for the Joint Council on Aging Aircraft/Joint
Group on Pollution Prevention (JCAA/JG-PP) No-Lead Solder Project. The JCAA/JG-PP Consortium is the first group to
test the reliability of lead-free solder joints against the requirements of the aerospace/military community.
The solder alloys selected for test were:
Sn3.9Ag0.6Cu for reflow and wave soldering
Sn3.4Ag1.0Cu3.3Bi for reflow soldering
Sn0.7Cu0.05Ni for wave soldering
Sn37Pb for reflow and wave soldering
Test vehicles were assembled using these solders and a variety of component types and the test vehicles are being thermally
cycled (from -20°C to +80°C). To date,5700 thermal cycles have been accumulated.
The solder joints on the components are being electrically monitored using event detectors and any solder joint failures are
recorded on a Labview-based data collection system. The failures of a given component type attached with SnPb solder will
be compared to the failures of the same component type attached with lead-free solders by using Weibull analysis.

For more than two years,experts,authorities and sales people in the electronic industry have talked about WEEE and
RoHS. In most cases,it has been theoretical and few companies in Scandinavia have any practical experience with lead
free production. What is even more significant is that many OEMs don’t have any knowledge about what actions they
have to do to meet the requirements for a successful implementation of WEEE and RoHS. In addition to a lack of
knowledge for EMS and OEM companies,the authorities in the Scandinavian countries have kept a very low profile
which undermines the political system in European Union and the consequences of the WEEE and RoHS directives.

European directive2002/95/EC (RoHS) bans the use of several substances for electronic assemblies by July 2006. These
regulations have a great impact on the Electronic Packaging and Interconnection Technology. They affect specifications and
handling of Components,Printed Boards,Materials,Manufacturing processes,Rework / Repair and last,but not least,the
Reliability and Costs of products. Lead is the element that most affects the electronic manufacturing processes and designs,
as it is part of the standard soldering alloy (Sn63Pn37).
International associations (JEITA and IPC’s Solder Products Value Committee) recommend the use of the SAC 305 alloy
(3% Ag,0.5%Cu,96.5%Sn) as the alternative to SnPb.
This paper describes a Lead-free Test Vehicle that was used to test both the Design For Manufacture (DFM) guidelines and
the process variations in comparison with the current SnPb process. The paper is the result of a co-development project held
between OCE and Celestica to validate and modify,if necessary,the design,assembly specifications,and process control
parameters associated with the new soldering alloy.
The project was developed to test all aspects of the Pb-free assembly process from the double sided reflow process,single
sided reflow with cure process,selective wave solder process to standard wave solder processes. Different rework processes
were also evaluated,such as manual soldering,hot gas rework and solder fountain rework for TH connectors. The goal was
to determine if there was a preferred process flow for this new technology and if it could handle different processes without
any direct effect on functionality,yield or Reliability.

The electronic industry has been migrating to lead-free solder alloys by legislation forces. In Europe the WEEE/RoHS are
scheduled to ban Pb alloys in July 2006. China is in process of preparing similar regulation. In Japan legislation governing
products containing Pb has already been established. In the US,some states are exploring legislation to require recycling of
electronics to reduce Pb in products. The objective of this work is to describe a study of Surface Mounted BGA Components
when using a lead-free solder paste and two different reflow profiles. The 387SAC solder paste alloy (95.5Sn/3.8Ag/0.7Cu)
was printed on PCBs (Printed Circuit Boards) for one specific phone project under study. The devices were submitted to
thermal cycling,shock,humidity,drop and red dye penetration tests according to Motorola’s standard tests procedures. The
BGAs component interconnects were inspected from cross sectioning for solder joints quality performance. Solder ability
tests showed to be correlating with the reflow process parameters and were used as guides to get the process improvement.
The laboratory analysis suggested the use of a different thermal reflow profile was required to increase the BGA joints
reliability.

At the same time the electronics industry is moving towards higher power and faster clock speed,components are becoming
smaller in size and packed more densely on circuit boards. Together these factors result in tremendous heat flux that must be
dissipated to improve performance and maintain reliability. As a result,the need for improved board level thermal
management is becoming more and more critical. In addition to improving traditional heat sinks mounted directly to
integrated circuits,designers are turning more frequently to thermal solutions that utilize the printed circuit board itself to
supplement heat dissipation. Based on application needs,thermally conductive dielectric materials with the following characteristics were investigated: 1)
thermal conductivity ranging from 1.7 to 3 W/mK; 2) halogen and phosphorus-free material,passing UL94V0 flammability
test; 3) environmentally friendly solvent-free process; 4) high glass transition temperature with excellent 288 oC solder float
and immersion test results; and 5) free-standing dielectric layer with processing conditions similar to FR-4. The
characteristics of the free-standing sheets were chosen in order that they could be processed as IMPCB,double sided
laminate (DSL),and hybrid combinations with single or multilayer FR-4 assemblies. In this paper the characteristics of
IMPCB’s made with a variety of filler systems and environmentally friendly polymeric systems are discussed. The effects of
the filler and polymer choices on achievable thermal performance,adhesion,and flammability are investigated. The
improvement in thermal stability through the use of a non-brominated resin system is discussed. Compositions with high
thermal conductivity,high glass transition temperature,and high electrical insulation resistance are evaluated.

Nowadays,the growth of electronic industry is remarkable. All electronic devices are getting smaller with higher performance and data
transmission speed. Therefore,we have developed a new profile-free copper foil whose surface roughness (Rz) is less than 1.5 µm with
satisfactory adhesion strength. A new original surface treatment of the profile-free copper foil provided affords good peel strength (0.7
kN/m or more) equivalent to that for the conventional roughened foil with sufficient reliability. With the new profile-free copper foil,the
conventional subtractive method is applicable to the wiring of 60 µm pitch or less,and the short-circuit fault of electroless Ni/Pd/Au
plating,which is prone to occur in fine wiring,will be restrained since the wiring is formed on a smooth surface. Moreover,the
transmission loss at 5 GHz will decrease by 8 dB/m since the surface roughness of the conductor line is suppressed.

Carbon Composite raw material property comparison are summarized below:
-Thermal Conductivity – Watts per meter ? Kelvin.
The core material can spread up to 620.0 W/m?K.
-CTE – parts per million per C.
Carbon Composite Laminate has a very low negative CTE,(-1.10 ppm/C) so it contracts very slightly as temperature rises.
Traditional materials expand considerably as temperature rises. When in plane,the user can tailor the surface CTE of a
standard Printed Circuit Board from 3ppm/C to 12 ppm/C,enabling direct die attach and WLP.
-Density – grams per cubic centimeter.
The material density (and therefore weight) is approximately equivalent to fiberglass. Standard FR4 is 1.85g/cm3 carbon
composite is 1.76-2.20g/cm3. No weight premium.
-Tensile modulus of elasticity – MSI (1,000,000 PSI).
The carbon composite is much more rigid than traditional materials. It is 4 to 10 times the rigidity of standard Fr4. Tensile
modulus is 34-130 MSI per layer depending on raw material selected.
-Dielectric constant – r (relative permittivity).
The relative permittivity of the new material is higher than traditional material,however,it is used only as a plane layer
(preferably ground plane) and is isolated from the copper vias. This material can be drilled through easily so that signals pass
through the carbon composite layer,are isolated,and still can be used throughout the entire board. This eliminates the
concerns of the Dielectric constant of the core material and allows users to simply design the PCB as normal concerning
vias.

This paper presents data collected from a set of electronics manufacturers using an automated optical inspection post-place
system for the purpose of both defect detection and process-control and process monitoring. The data represent a range of
geographical locations (US,Europe,Asia),a variety of different products (cell phones,PC motherboards,etc.),and a long
period of time (seven years). Based on these experimental data,we provide real-life dramatic examples of how analysis of
both attribute and variable data over the short and long term can help increase first-pass yield,keep first-pass yield steady,
and decrease set-up time. These analyses methods can be used in combination with real-time feedback to continuously
improve product quality and,thereby,achieve earlier returns on investment.

With the introduction of Lead-free solder,voiding within BGA joints is potentially a major issue during PCBA manufacture.
With BGA components sometimes costing hundreds or even thousands of US Dollars,there has to be an understanding about
when voiding within the joint is excessive.
There are a number of specifications that a manufacturer can refer to but with respect to BGA joints,IPC-7095A is probably
the most comprehensive. It has an entire section on voiding within the BGA ball and limits on when the void size becomes
either a Process Control issue or a Corrective Action Indicator. However,some of this information seems to conflict with
other IPC specifications,for example IPC-A-610D. Instead of trying to set a global specification,this paper investigates
whether the limits specified within IPC-7095A were acceptable to a particular Contract Manufacturer and their OEM
customer.

Over the last several years there has been a great deal of advancement in post-print inspection technology. The capability to
inspect printed solder paste deposits immediately after the printing process and immediately before the component placement
process has become more accurate,more repeatable and much faster. Post print solder paste inspection systems which are an
integral feature of the printing machine itself or a standalone automated optical inspection (AOI) system are now able to
provide much more reliable inspection capability at or near the speed of the product cycle times.
However,regardless of how sophisticated,no post print inspection system can actually correct the defects it detects. The
existing post print inspection systems can certainly identify the defects and notify the operator or process engineer of a
problem. The identified defect can be fixed before it becomes a more costly defect than if it were discovered later in the
manufacturing process. A process engineer or technician must evaluate the solder paste printing performance data generated
by the post print inspection and/or statistical process control (SPC) systems to determine the “root cause” of the defect and
what action is required to actually eliminate or minimize the problem from reoccurring. No post print inspection system has
ever eliminated any defect from reoccurring without a process engineer implementing permanent corrective action.
The concept of a closed-loop process control solder paste printing process involves a system that not only detects the defects
but also has the intelligence to make adjustment to the process (primarily adjustments to the printing equipment’s operating
parameters) to prevent them from reoccurring. This paper will discuss various concepts of closed-loop process control
involving the solder paste printing process. The discussion includes the current status of our research in this field,benefits,
limitations,the technology required for implementation and future innovations.