BGA’s,ceramic capacitors,and similar strain sensitive components are used extensively throughout the automotive and consumer electronics industries. Unfortunately these components can be easily damaged when exposed to excessive board strain and flex and induce microscopic defects within the components that typically are undetectable. Additional thermal and mechanical cycling can cause these defects to propagate over time and ultimately lead to component failure,product failure,and customer dissatisfaction. Since defect detection is ineffective,defect prevention is the key to success.
This paper will review in depth the various failure modes,identify high risk assembly processes,and outline the critical prevention strategies that need to be implemented to produce a defect-free quality product. Topics will cover product design,process design,and verification strategies.

Like many other electronics industries,the automotive electronics industry has long been concerned about ESD. As dramatically seen in the news today,quality recalls can detrimentally affect the faith and loyalty that a customer has for a company’s products. Automotive collision avoidance radar systems,Telematics and some audio products are currently made with parts that are extremely sensitive to ESD. Robust ESD controls at the vehicle electronic system suppliers are needed to protect their customers from ESD. This in most cases can be done by complying with the ESD control industry’s standards ANSI/ESD S20.20 and IEC 61340-5-1. The ESD controls built around these standards have been successfully used for over the past 20+ years,but will need improved upon for more sensitive future devices. In addition,ESD control issues at the assembly plant will also be discussed as current guidelines may need to be improved given the growing trend for more sensitive electronics in vehicles and at the same time,the explosion of even more vehicle parts made from static generative plastics.

• Genesis in December 2008
• Follow-up discussions APEX 2009
• Input received from SMEs
• Conference Call July 22,2009
• Discussions IPC Midwest 2009
• First white paper issued by IPC SPVC June 2010

Using X-ray imaging,solder corrosion,resembling metal migration,had been observed under QFN (Quad Flat No-Lead package) devices and chip resistors on circuit boards that were processed with two SAC 305 alloy solder pastes after 500 hours of exposure to 85ºC and 85% R.H. with no applied voltage. Analysis of the material under QFN’s by SEM (scanning electron microscopy) and energy-dispersive X-ray spectroscopy showed it was primarily a tin compound. This phenomenon was only observed for components that had a relatively large quantity of flux residue trapped underneath them. Further investigation was made using six different SAC305 alloy solder pastes and solder paste test coupons with copper OSP and NiAu metal surface finishes. The test coupons were examined with X-ray imaging before exposure to 85ºC and 85% R.H. and then after 250,500,750 and 1000 hours of exposure. On the NiAu boards,tin corrosion was observed for five of the six pastes after 250 hours exposure,and after 750 hours exposure for the sixth paste. For OSP boards,three pastes showed corrosion after 250 hours,an additional paste after 750 hours,and two pastes showed no corrosion after 1000 hours exposure. The corrosion is dependent on solder paste flux chemistry,solder alloy and the board’s metal finish. The investigation discussed here concerns three solder paste flux chemistries,SAC305 and 63 Sn 37 Pb alloys and 3 reflow conditions. Flux chemistry had the greatest effect on tin corrosion under QFN components; however SAC305 corroded faster than 63 Sn 37 Pb. Reflow conditions had almost no effect.

The effects of nano-TiO particle additives on the microstructure and microhardness of the 2 Sn3.5Ag0.5Cu composite solder were studied. Results show that alloying with nano-TiO 2 particles dramatically reduced the formation of primary ß-Sn phase,the average size of Ag3Sn phase,and the spacing lamellae in the Sn3.5Ag0.5Cu composite solder. This is attributed to the adsorption of nano-TiO2 particles with high surface free energy on the grain surface during solidification. Microhardness improved with the addition of nano-TiO 2 particles,which refinded Ag Sn INCs. The refined IMCs acted as a strengthening phase in the 3 solder matrix and enhanced the Vicker’s microhardness of the Sn3.5Ag0.5Cu composite solders,which corresponds well with the prediction of the classic dispersion strengthening theory.

In globally competitive markets,managing product quality,reliability and risk is not an option. However,it also brings its own unique set of challenges to complex organizations:
- Product design teams need to gain early insight into product reliability - A systematic process is needed to plan for quality,and to identify and mitigate risks - The product design must be more closely aligned with customer requirements - Reliability and quality must be balanced with lifecycle costs and profitability - A centralized system is required to enable guided corrective actions and prevent repeat issues Today,many companies struggle with these demands,creating fragmented tools and processes that delay analysis and prevent communication,the consequences of which range from undesirable to catastrophic,including: Escalated costs,undetected risks,product recalls,decreased consumer confidence,and loss of market share. Customer demands and government oversight have never been greater,which is further amplified with 24 hour access to consumer blogs and media coverage. Every corporate boardroom is forced to consider the
impacts of quality,reliability and risk on their business.

- Regulations are driving increasing IPC-1752 use
- More restricted substances and product categories in scope
- The business challenge is much bigger than “regulatory compliance”
- Teams increasingly manage multiple,evolving standards
- Business goal: Early visibility
- How? Systematically acquire,validate,and maintain environmental data
- Progressive disclosure
- Required: Data Management and Systems Integration
- Enabling continuous data acquisition & analysis
- Compliance Summary: Key Business Needs
- Product Environmental Performance is the next wave
- Driver: Product environmental footprint
- Life Cycle Environmental Impact
- Extended BOM for LCA Modeling and Regulatory Compliance

- Correlating film properties to the propensity to whisker will lead to the development of a comprehensive whisker growth model and create successful mitigation strategies.
•Hillock and whisker growth have been correlated to measureable film properties
–Film stress evolution
–Grain boundary mobility
–Crystallographic texture evolution
•Film properties are influenced by basic processing parameters
–Electrolyte type
–Electrolyte additives
–Deposition current density
–Film thickness

The lead-free directive from the EU has created a number of challenges for high reliability electronic applications. Key among those challenges is the need to address the issue of tin whiskers. While complete elimination of the tin whisker phenomenon on tin finished materials is not possible there are steps that can be taken to manage and mitigate the creation and effect of tin whiskers. Delphi has focused on mitigation steps to reduce the likelihood of tin whisker occurrence and has implemented processing measures to reduce the potential for damage by tin whisker that do occur. Those mitigation steps and findings from validation work and product performance reviews are shared.

•Board-level drop shock test was performed on 9 assemblies
–63 parts / board
–Parts representative of military package styles
•Assembled on Pb-free compatible laminate with SAC 305 solder
•Selection of the non-BGA parts reworked with SnPb solder
•Metallurgical characterization
•Assemblies fixtured to drop table and subjected to 500Gs for a total of 20 drops
•In-situ shock response,net resistance and strain recorded
•Physical FA performed to characterize mechanical damage