The continuous temperature resistance of electrically insulating materials can be judged by examining the effect of thermal stress loads on the electrical properties,such as moisture and insulating resistance,tracking resistance,etc.
Which effects on the electrical insulating properties of solder masks are to be expected,in particular under subsequent climatic stress? This paper will present and discuss the results of moisture and insulating resistance tests in different climates as well as further electrical properties from both continuous storage tests at 150°C for 2,000 hours and thermal cycling tests over 1,000 cycles,-40°C/+150°C. The load at the high cycle temperatures shall be compared with those from the continuous temperature storage tests. Furthermore,the theoretical base of this methodology shall be discussed.
In order to consider any potential "pre-damage" caused by the various surface finishes,tests have also been performed with a "preliminary stress load" comparable to that of the printed circuit board and electronic assembly. The influences of processing with various surface finishes such as Nickel/Gold finish (ENIG),chemical tin finish (CSN) and HAL (Hot-Air Levelling) on the thermal cycling resistance have also been examined. The paper shall go on to discuss investigations into the moisture and insulation resistance in different climates as well as the influence of the base material and layout as well as precleaning and solder mask thickness on the thermal cycling resistance.
In addition,comparisons shall be made between aqueous-alkaline and polyalcohol developable materials.

The European Union passed two directives in 2003 addressing the increasing amount of waste from electric and electronic equipment: (1) Directives 2002/96/ECi – Waste Electrical and Electronic Equipment (WEEE) and (2) Directive 2002/95/ECii – Restriction on the use of certain Hazardous Substances in electrical and electronic equipment (RoHS).
The RoHS Directive focuses on restricting the proliferation of six hazardous substances in any product which plugs into an electrical outlet or uses a battery. Member States shall ensure that,from 1 July 2006,new electrical and electronic equipment put on the market does not contain lead,mercury,cadmium,hexavalent chromium,polybrominated biphenyls (PBB) or polybrominated diphenyl ethers (PBDE).iii The cost of not complying with the RoHS directive,or any environmental directive,is enormous. The value/cost ratio of proper
documentation is immeasurable.
There are several papers,articles,and other publications on how to make the product compliant or on the steps needed to set-up a compliance team. Companies will sell you their component compliance database; hold your hand through a consulting session on how to create the compliance team; talk to you about how to make the products in the company compliant. These are all
great first steps to meeting the directive. But what happens when a product is selected for market analysis,and is actually audited for the six banned substances?
This paper provides direction on documenting the product’s readiness to meet the RoHS directive as part of a self-declaration strategy.

Tetrabromobisphenol-A (TBBPA) is a commercial flame retardant used in rigid FR-4 printed wiring boards (PWB). It is the single largest volume brominated flame retardant in the world. In this application,the TBBPA is fully reacted into the epoxy resins that form the base material of the PWB. TBBPA’s leadership position in the rigid printed wiring board market is due to several factors,including reliable performance over time.
This paper will look at the benefits of TBBPA as a flame retardant in epoxy resin PWB. It will also address the current regulatory status of TBBPA and PWB recycle. An update on the status of the EU Risk Assessment on TBBPA and other industry assessments that compare TBBPA to alternative flame retardants for PWB will be included.

The IPC's Lead Free program addresses one of the 6 Hazardous Substances regulated by the RoHS directive. Certification to the QC 080000,the IECQ HSPM Specification,addresses the other 5 Hazardous Substances called out by RoHS thus addressing all 6 of the restricted substances. The synergy of applying both systems allows a company to accomplish total due diligence.
Directive 2002/95/EC of the European Parliament and of the Council was published on 27 January 2003. Restriction of the use of certain Hazardous Substances in electrical and electronic equipment (commonly known and referred
to as RoHS) went into effect July 1,2006. The RoHS directive was established by the European Union in order to reduce waste harmfulness,and restrict certain types of hazardous substances from being imported into the EU. The directive bans the following six substances,above the noted concentration levels,in electrical and electronic equipment:
Substance
Lead – Pb
Mercury – Hg
Cadmium – Cd
Hexavalent Chromium – Cr(VI)
Polybrominated biphenyls – PBB
Polybrominated diphenyl ethers - PBDE
In May 2006,the European Union published a guidance document intended to assist companies as they attempt to comply with the EU RoHS directive. Key issues addressed within the Guidance include the establishment of a Compliance
Assurance System (CAS) and establishment of the underlying principles that might be used to guide member states that make up the European Union in RoHS enforcement. Also addressed by the guidance document are the type of documentation that ‘producers’ (within the specific definition given in Article 3 of the Directive) might be advised to keep,the ways in which Member State enforcement authorities might use such documentation to check for RoHS compliance,the ways in which sample preparation,and analytical testing might be employed to avoid inconsistent enforcement decisions between Member
States.

Reliability of RoHS compliant products is investigated in this study. Emphasis is placed on the lead free solder joint
reliability. Solder is the electrical and mechanical “glue” of electronics assemblies. Will lead free solders provide the
characteristics necessary to allow the world to depend on it in the future? This paper cannot answer this question; however,it
will help all participants in the soldering world better understand what needs to be done in order to answer this question and
plan for the future.

Many professionals in the electronics manufacturing industry have,or eventually will,face the issue of determining
whether the materials of construction for printed wiring assemblies (PWAs) are compatible with each other for the
products produced,and producing objective evidence of this compatibility. Such a determination may be a
monitoring or changing of an existing in-house manufacturing process,the development of a new manufacturing
process,or determining if assemblies produced by a subcontractor are acceptable. The concept of materials
compatibility can be very broad,depending on what factors are chosen for examination,but is critical to
understanding the reliability of manufactured hardware.
This paper focuses on the use of the IPC-B-52 standard printed wiring assembly as a test vehicle to meet these
needs,with illustrative data from a high reliability avionics manufacturing process,including lead-free evaluations.

The in-circuit test (ICT) of printed circuit boards (PCBs) assembled with Lead Free solder was anticipated to be problematic
by industry test engineers,due to contact failures associated with the perceived lack of pin probeability of Lead Free solder
pastes and fluxes. The introduction of Lead Free processing could potentially present new challenges to the established ICT
process.
A good electrical contact between test probes and test targets on the unit under test (UUT) is fundamental to the success of
ICT. The testing of tin-lead soldered PCBs is a mature process,supported by years of effort,many studies and numerous
improvement projects,carried out on pin probable solder paste,flux development,design for test (DFT),test probe and
fixture design.
A study of Lead Free processing and the impacts to test and inspection equipment was undertaken. All available information
from customer product introductions,test equipment vendors and industry resources was collated and the risks involved in
moving from tin-lead solder to Lead Free solder were identified.
This paper describes the method and experimentation used to investigate ICT probe contact on Lead Free boards. A test
vehicle was designed with different sized test pads and vias and an ICT fixture was manufactured. Process and test
influencing factors were identified,including various Lead Free solder pastes and board finishes. Using Six-Sigma
methodology,a number of experiments were designed,results analyzed and the significance of the experiment parameters
(factors) investigated. Recipes were developed for achieving good ICT probe contact on Lead Free boards.

Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the
solder joint. The degree of wetting,the microstructure (in particular the intermetallic layer),and the inherent strength of the
solder all factor into the reliability of the solder joint. This paper presents experimental results on the effect of reflow profile
on both 63%Sn 37%Pb (SnPb) and 96.5%Sn 3.0%Ag 0.5%Cu (SAC 305) solder joint shear force. Specifically,the effect of
the reflow peak temperature and time above solder liquidus temperature are studied. Nine reflow profiles for SAC 305 and
nine reflow profiles for SnPb have been developed with three levels of peak temperature (230oC,240oC,and 250oC for SAC
305; and 195oC,205oC,and 215oC for SnPb) and three levels of time above solder liquidus temperature (30 sec.,60 sec.,and
90 sec.). The shear force data of four different sizes of chip resistors (1206,0805,0603,and 0402) are compared across the
different profiles. The shear force of the resistors is measured at time 0 (right after assembly). The fracture surfaces have
been studied using a scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS).

Lift-off (fillet-lifting) and land-lifting phenomena,which occur in wave soldering with Sn-Ag-Cu (SAC) solders,depend
on the physical properties of the solder and the laminate material used. A new Sn-Ag-Cu-Ni-Ge (SACNG) solder and
two types of printed wiring board (PWB) laminate materials with higher glass transition temperatures (Tg),lower
coefficients of thermal expansion (CTE) and higher peel strengths at high temperatures have been developed to suppress
fillet- and land-lifting. The SACNG solder and laminate materials have shown excellent reliability in the wave
soldering process and thermal cycling evaluation. Moreover,the valid physical properties of laminate materials for
suppressing fillet- and land-lifting have been investigated by FEM analysis.

Meeting the RoHS directive will require the transition from the historical tin-lead based system of materials to one that
does not contain lead. This is of course is not straight forward as it is impossible to control 100% component material
compositions. It is therefore entirely possible that components with lead finishes will find their way into Lead Free
processes. The concern is that lead contamination occurring in this way results in 1 to 10% level of lead,and that this
lead is not uniformly distributed,but segregates to the grain boundaries and joint interfaces [1]. But what is the effect of
this on thermal fatigue. The work reported here will describe experiments where the lead level in solder joints was
controlled by altering the plating on component terminations and using controlled solder compositions. Microstructural
examination verifies the segregation of lead. The built assemblies were then thermally cycled between –55 and 125ºC for
2000 cycles to assess this effect on reliability. Hot peel tests were also run to simulate problems that may occur is
secondary wave operations where the fillet strength collapses and components can detach with little force at temperatures
above 180ºC. The use of indicator test kits to detect lead were also evaluated on this set of reference samples. This paper
will discuss these results and the likely impact on the industry and the necessary precautions.