Thursday, 20 May 2010

Introduction and Conference Kick-off: “Better Quality, Reduced Costs and Increased Competition.”
Speaker: Lars Wallin, IPC Europe

A lack of solder joint reliability can result in assemblies with serious errors that are costly to repair and decrease competitiveness and yields. The speech will include the following:

• Why is reliability so important today?
• What does electronic hardware production cost in general?
• What does inspection and repair cost?

How to secure reliability of the bare PCB
Speaker: Bo Andersson, NCAB Group

What is the definition of reliability of a bare board from both the supplier’s and user’s perspectives? Andersson will discuss different parameters and how they drive costs. How can international standards and other tools be used efficiently to assure that bare boards have high quality and reliability — no matter where they are sourced from.

No short cuts to lead-free solder joint reliability: facts & trends, what every practitioner needs to know
Speaker: Jean-Paul Clech, EPSI USA

The problem of solder joint reliability has been compounded by the proliferation of soldering alloys and the multiplicity of solder ball and paste compositions. While some trends have emerged — e. g. some alloys look promising under thermal cycling conditions but perform poorly under mechanical loading, or vice-versa — there is no simple, universal answer to the question of lead-free solder joint reliability. In the end, reliability remains the responsibility of the product management team and a minimum investment of time and resources will be needed to establish an acceptable target performance. This talk will review and discuss some of the above trends, while advocating the need for a proactive approach to lead-free solder joint reliability.

Results from two test runs in Sweden regarding which parameters are important and which are not to design and produce a highly reliable PCB
Speaker: Lars Wallin, IPC Europe

At electronic exhibitions in Sweden in 2008 and 2010, three different boards were produced in a high-tech assembly and soldering line using lead free. The PCBs were inspected manually according to IPC-610 class 2, processed in SAM (Scanning Acoustic Microscope), SEM (Scanning Electronic Microscope), AOI and X-ray machines. In addition, several microsections were done.

The results of the quality and reliability examinations regarding the bare boards, the size of footprints, the component placements, the health of the components (BGA, QFN and POP) after one or several reflow processes will be presented.

Process qualification of lead-free process versus tin-lead
Speaker: Lorenza Lombardi, BAMES Italy

Since the early 2000s, the SEM Materials Laboratory has worked to select and test the compatibility of new chemicals and materials used for lead-free processes (i.e. solder alloy, fluxes, pcb finishing, component finishing, etc.).

One of the most important steps of this work has been the analysis of lead-free solder joints before and after various stresses such as ATC, T & H, Shock & Vibration and the comparison with the tin-lead process.

The characterization of solder joints has been carried out through activities like pull and shear test, metallographic analysis, x-ray and functional and/or electrical test.

This speech highlights some of the analyses performed by SEM Materials Laboratory on customers’ products from various market segments (automotive, electronics, industry, telecommunications…).

The speech is not exhaustive of all qualification activities necessary to get a complete overview of lead-free process performance, but it puts in evidence those that are widely used.

Design for reliability for lead-free electronic products
Speaker: Werner Engelmaier, Engelmaier & Associates

Reliability issues for lead-free electronics result from the high soldering temperatures required. Tin-lead designs survived in many cases on pure serendipity; this no longer works for lead-free assemblies. Design for reliability for PCBs, components and solder joints need to take the resulting requirements into account. Some solution options will work universally, but others need to be optimized according to design and application specifics.  

Friday, 21 May 2010

Workshops 08:30-12:00 (Separate registration required)

Lead-free solder joint reliability: material properties (what to look for) & acceleration factors
Instructor: Jean-Paul Clech, EPSI USA

The performance of lead-free soldered assemblies is dictated primarily by solder properties and the material response of solder joints to test conditions. Identifying and understanding the relevant material properties is the first step of the alloy selection process and the road to reliability. The timely assessment of lead-free solder joint reliability also requires the use of efficient accelerated thermal cycling profiles, coupled with reasonably accurate acceleration factors (AFs) that allow for the extrapolation of failure times from test to field conditions. Since test data alone does not give product life estimates, this extrapolation procedure is the only way to make an educated guess at lead-free product field reliability or the lack of it.

This workshop first reviews the essential solder properties that guide the alloy selection process. Seven algebraic AF models will be presented for SAC305, SAC387/396/405 assemblies. Relevant test profiles are discussed, as well as the basic ingredients — solder properties and applicable failure data — and methodologies that are needed to develop AF or life prediction models for lead-free soldered assemblies. The efficiency of accelerated thermal cycling profiles is discussed in parallel with the use of AF models that capture creep and dwell time effects for various solder compositions. The seven models being presented are exercised against independent test data, illustrating how accurate, conservative (or not), or overly conservative the different models can be.

Main topics:

• Lead-free reliability trends and challenges: alloy proliferation and impact on reliability assessment.
• The importance of solder material properties: what properties are most important, why strength is not an indication of reliability and how properties enter AF models.
• Thermal cycling conditions: standard profiles (lead-free vs. SnPb profiles), ramp-rate and dwell time effects; comparison of test results, failure modes and acceleration factors for short vs. long dwell temperature profiles.
• Life-prediction techniques: strain or strain energy based models; impact of creep on acceleration factors, and effect of creep parameters on the formulation of several AF models.
• AF accuracy of seven examples of SAC305/405 acceleration factors; conservative versus non-conservative versus overly-conservative models.

Increase reliability and quality with the help of IPC standards through the entire production chain of rigid electronic hardware
Instructor: Lars Wallin, IPC Europe

The seminar is aimed at production managers, production technicians, designers, CAD staff, PCB manufacturers, purchasers, quality engineers, and related personnel.

Main topics:

• IPC standards and training in the world of electronic designers and CAD staff. Participants can follow how a circuit board is born and takes its first tottering steps. Contents of IPC design standards IPC-2220 series and IPC-7351A will be covered.
  
• IPC standards and training in the world of the PWB manufacturer. Participants can follow how a PWB is born and develops into an unruly teenager. Contents of IPC-6012B and IPC-A-600H, IPC-455X-series for PWB surface finish and IPC-4101 for base materials and IPC-A-600 certification training will be covered.
• IPC standards and training in the world of the circuit board assembler. Participants can follow how a circuit board develops into a full-grown circuit board. Contents of IPC-A-610E, J-STD-001E, IPC-7711/21B and IPC-A-620A will be covered.
• IPC standards and requirements in the cleaning world of circuit boards. Participants can follow how a circuit board should be cleaned so that it lives a long time until a late retirement.

Reliability issues and solution options for lead-free soldered electronics products
Instructor: Werner Engelmaier, Engelmaier & Associates

The switch to lead-free solders has raised a number of issues and problems regarding the manufacture, processing, and reliability of electronic products. The reliability of these electronic products can only be assured with “design for reliability” based on a “physics-of-failure” understanding of these problems. Given the high temperatures required for most lead-free soldering processes, “design-for reliability” first needs to assure the survival of the electronic product during the assembly process.

In this course, the special reliability threats to the solder attachments themselves as well as to the printed circuit board (PCB) substrates and components coming from the utilization of lead-free solders will be discussed. These threats to reliability will be detailed as to the load drivers and the resulting failure modes and illustrated by pertinent examples and illustrations. Solution options in terms of material selection, design and specification steps, and processing parameters will be suggested.

The complex nature of the interacting mechanisms underlying thermally induced solder joint fatigue combined with the highly temperature-, time-, and stress-dependent behavior of solder will be explored. Solder creep-fatigue behavior as well as the different load drivers such as thermal cycling, vibration, and mechanical shock are explained. The available information for the creep-fatigue behavior of lead-free solders is as yet inadequate for solders other than SAC 405, 305, 205, 105 and SnAg for the determination of acceleration factors and the development of creep-fatigue models.

Appropriate testing to assess the extent of these various reliability threats will be suggested and discussed. Strategies to assure the reliability of the solder attachments, printed circuit boards and components in electronic product subjected to lead-free soldering will be explained.