Nihon Superior’s SN100C P600 D4 Paste Wins a 2009 Global Technology Award

SN100C P600 D4 is a halogen-free high-reliability no-clean lead-free solder paste that does not contain F, Cl, Br and I. Designed as a high-reliability solder paste for high-density assembly with stable printability, the paste provides excellent reflow with good wetting and minimum incidence of mid-chip balling, and low residue. Additionally, it typically can be reflowed with a profile similar to that which is commonly used with SAC305 and SAC405 with 240°C peak.

SAC105 bump ageing experiments

Factiva: "Cold bump pull tests performed on wafer level chip scale packages using SAC105 solder bumps show an increase in the occurrence of brittle failure modes with aging temperature and time,' scientists in Quezon City, Philippines report.

'Fast intermetallic growth at 0-1000 h can be attributed to (Cu, Ni)(6)Sn-5, while the decrease in intermetallic growth rate at t> 1000 h can be attributed to diffusion processes leading to (Cu,Ni)(6)Sn-5 and (Ni,Cu)(3)Sn-4 formation and growth. Ni diffuses toward the solder bulk and saturates at 175-200 degrees C, while Cu diffuses from the under bump metallization (UBM) toward the solder bump at 125-150 degrees C. Interactions between Cu and Ni atoms lead to saturation of their atomic % gradients due to intermetallic formation,"

Solder material maker Shenmao expects revenues in 2010 to grow 20% on year

Digitimes: "Taiwan-based solder material maker Shenmao Technology expects its revenues in 2010 to grow 20% and reach a record high compared to 2009.

The company's October 2009 revenues dropped about 10% to NT$516 million (US$16.03 million) since the PCB industry is entering the low season, revenues are also expected to see a 10% sequential decrease in the fourth quarter, weaker than its earlier expectation of a flat or single-digit decline, according to the company.

On the other hand, Shenmao's shipments and revenues generated from BGA solder spheres both hit records in October, with revenue share reaching 6.4%. Revenue share of bumping solder pastes was less than 1%, but the company expects the segment to see rapid growth in 2010. More than half of Shenmao's products are used in notebooks.

The company is focusing on high-margin products which account more than 30% of total revenues. It estimates consolidated gross margin to remain around 18% in the fourth quarter."

Next Generation Adaptable NANOPillar Bumping Technology

Factiva: "'Looking forward, NANOPillar(TM) bumping is a key enabling technology for cost reduction by Au wirebond displacement in conventional packages as well as for emerging 3D packaging applications. The interest in Pillar bumping by our customers has been overwhelming; particularly in light of the diverse solder alloy options that are enabled. In developing our NANOPillar(TM) bumping technology, our focus has been to develop a proprietary, next generation pillar bumping technology with unsurpassed solder composition versatility.'"

Occam Process WO patent

WO2009140050A2: "A system for prototyping electrical circuits, as well as creating production circuits, without using solder. Stand-in electrical components are placed on a carrier and scanned . From the resulting data, a machine tool or laser ablation system then creates a negative master with aperture(s) into which production components are placed and secured. Component leads or packages are encapsulated with electrically insulating material with vias exposing the leads.

Traces connect appropriate leads forming a circuit sub-assembly which can serve as a basis for a circuit assembly formed through a reverse-interconnection process."

Applied Nanotech Awarded $500,000 for Tin Whiskers

Nanotechnology: "During this eighteen month Phase II Small Business Innovation Research program, which results from successful completion of a Phase I award, Applied Nanotech will focus on optimizing its patented (pending) process for the mitigation of tin whiskers. Both the MDA and NASA have reported that tin whiskers have been the cause of more than $1 billion in catastrophic damage to satellites, missiles, and other electronic equipment.

Current recognized mitigation techniques add cost and complexity to the manufacturing process and have had mixed success. Our unique ability to perform tin whisker remediation with a pulse of energy, while simultaneously preventing new whiskers from growing, provides a distinct advantage over competitive methods.

'As the world is moving toward lead free solder, the tin whiskers issue will become very problematic, not only for defense and aerospace applications, but for all electronic products,' said Dr. Zvi Yaniv, CEO of Applied Nanotech, Inc.

'This improved method of remediation of tin whiskers is a direct outgrowth of our activity in technical inks and pastes,' said Doug Baker, CEO of Applied Nanotech Holdings, Inc. 'We continue to broaden the applicability of our technology to generate increased revenues.'"

Henkel introduces zero halogen multicore HF108 solder paste

EMSNow: "Though industry consortia have set some competing standards as to the acceptable levels of halogen, the common benchmark is up to 900 ppm bromine, 900 ppm chlorine and maximum total halogens of 1500 ppm. Henkel, however, has developed a material that has zero deliberately added halogens, yet has the excellent reflow and stability characteristics normally associated with halogen-containing materials.

'Multicore HF108 has no intentionally added halogen and is under the limit of detection in the rigorous oxygen bomb/ion chromatography test,' says Steve Dowds, Henkel Global Product Manager for Solders. 'Taking out the halogen is easy -- the difficult part is how to replace it.'"

Lead free production & problems when changing the processes

evertiq.com: "In general, different variations of the Sn-Ag-Cu alloy (SAC), with silver content from 3.0% to 4.0%, are all acceptable compositions for lead-free soldering (including reflow and wave soldering). Studies using SMT test vehicles, by IPC in collaboration with solder suppliers and EMS companies (such as Flextronics), have concluded that there is no significant difference in the process performance and thermal cycling performance among these different variations of the alloy composition.

However, when the silver content is much lower (such as SAC105), the thermomechanical reliability performance is adversely affected, due to the reduced amount of Ag3Sn intermetallic compound in the solder microstructure. SAC105 is more suitable for BGA/CSP balls for handheld products where drop test reliability is more critical than thermal cycling reliability."

The tin-copper alloy is a viable alternative for wave soldering of cost sensitive products where reliability is less critical. Several variants of the Sn-Cu alloy have also been considered by the industry, including silver (Ag), nickel (Ni), and other elements as alloying additions. In addition to cost, reliability, hole-fill, and copper dissolution (especially for PTH rework) are important considerations when selecting an alloy for wave soldering.

Introducing and qualifying a new solder alloy for volume production is a significant undertaking which demands an industry-wide effort. Flextronics is working with several industry consortia to study various alternative lead-free alloys, for solder paste, bar, BGA solder balls, etc., with the hope of finding a common alloy that is suitable for across-the-board applications.

Lead-free fillet tearing

EMT Worldwide: "Selected combinations of tin / silver / copper with a silver content of 3% - 4% are prone to cause this tearing during solidification of the solder. Tin / copper and tin / copper / nickel do not seem to feature this defect type. The solder is rough in appearance due to the shrinkage of the metal between the tin dendrites. There is no evidence currently that this has any impact on the reliability of the solder joints."

EWI Signs Agreement With S-Bond Technologies

Earth Times: "EWI SonicSolder is an EWI patented binary lead-free solder alloy that melts at 231 degrees C. In conjunction with ultrasonic soldering, it can be used to join difficult-to-wet materials like aluminum, titanium, glass, ceramics, and dissimilar materials. Potential applications include tubing, electronics, medical products, and structural components. In various base-metal (copper, aluminum, titanium) combinations, shear strength of about 5 ksi has been obtained. Currently available in ingot form, the solder will be available in a wire form at a later date."

Intermetallic Formation and Fluidity in Sn-Rich Sn-Cu-Ni Alloys

Scopus: "This paper investigates the phase equilibria and solidification behavior of Sn-Cu-Ni alloys with compositions in the range of 0wt.% to 1.5wt.% Cu and 0wt.% to 0.3wt.% Ni.

The isothermal section at 268C in the Sn-rich corner was determined. No evidence for a ternary phase was found, and the section is in good agreement with past experimental studies that report wide solubility ranges for (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4. The vacuum fluidity test was applied to compositions that are liquid at 268C to map the variation in microstructure and flow behavior with composition in this system. Significant variations in fluidity length were measured among the Sn-Cu-Ni alloys, and the variations correlate with the microstructure that develops during solidification.

The generated fluidity map enables the selection of Sn-Cu-Ni solder compositions that exhibit good fluidity behavior during solidification and form near-eutectic microstructures."

Synthesis and DSC study on Sn3.5Ag alloy nanoparticles used for lower melting tempera

Scopus: " A possible way to decrease the melting temperature of a solder alloy is to decrease the alloy particle size to the nanometer range. Sn3.5Ag nanoparticles with different size distribution were synthesized using chemical reduction method by applying NaBH4 as reduction agent. The melting properties of these synthesized nanoparticles were studied by differential scanning calorimetry (DSC), and size-dependent melting temperature depression of these nanoparticles has been observed. Gibbs-Thomson equation was used to analyze the size-dependent melting temperature property, giving a good prediction of the melting temperature depression for the Sn-based lead-free solder alloy nanoparticles."

Effects of Ni addition on the interfacial reactions between Sn-Cu solders and Ni substrate

Scopus : "This research investigates the effects of adding a small amount of Ni to solder.

The interfacial reactions between Ni and the Sn-Cu solders at 250C are examined. Two sets of Sn-0.7wt% Cu-xNi solders and Sn-1.0wt% Cu-xNi solders (x=0.02, 0.05 and 0.1wt%) were prepared. The results reveal that the interfacial reactions are very sensitive to Ni. With increasing Ni addition, the reaction phase grain, Cu6Sn5, becomes larger and its morphology changes from a rod-like shape into a faceted structure. The reaction progressions are accelerated in comparison with those without Ni addition. The solder spreading effect on the Cu6Sn5 morphology was also investigated. Cu6Sn5 exhibits a gradual change in microstructure from the center to the rim for the case when the solder ball spreads over a Ni substrate. However, the solder does not alter the Cu6sn5 microstructure while reacting on a small Ni pad without spreading. This suggests that the Cu and Ni contents in the solder near the interface vary during the solder ball spreading process."

Investigation of rare earth-doped BiAg high-temperature solders

Scopus : "In the present work, the microstructure and properties of the rare earth Ce-doped BiAg solders with various Ag content are investigated.

The results indicate that the maximum of the shear strength appears in the BiAg solder joints containing 5 and 7.5 wt.% Ag. At the same time, a similar trend appears in the hardness test of the BiAg bulk solders. Moreover, the results show that the microstructure and properties of the solders can be modified due to the unique properties of rare earth element. Small amounts of rare earth addition may enhance the wettability of SiAg solder on Cu substrate, and result in the increase of the shear strength of the solder joints. However, the rare earth addition may not give obvious influence on the melting temperature and the electrical conductivity. Thus, it is expected that the BiAg solder containing small amounts of rare earth element may possess a better potential as a replacement for high-Pb solders"

Effect of praseodymium on the microstructure and properties of Sn3.8Ag0.7Cu solder

Scopus: "Effects of Pr addition on wettability, microstructure of Sn3.8Ag0.7Cu solder were studied, the mechanical properties of solder joints were investigated and the fracture morphologies were also analyzed in this paper.

The results indicate that adding appropriate amount of Pr can evidently improve the wettability of solder, and it is also found that Pr can refine the β-Sn dendrites and reduce the intermetallic compounds growth inside the solder due to the fine PrSn3 particles formed in the solder which can act as heterogeneous nucleation sites. Moreover, the joints soldered with the SnAgCuPr solders possess sound mechanical properties which may result from the finer microstructure improved by the Pr"

Development of Au-Ge based candidate alloys as an alternative to high-lead content solders

Scopus: "Au-Ge based candidate alloys have been proposed as an alternative to high-lead content solders that are currently being used for high-temperature applications. The changes in microstructure and microhardness associated with the addition of low melting point metals namely In, Sb and Sn to the Au-Ge eutectic were investigated in this work. Furthermore, the effects of thermal aging on the microstructure and its corresponding microhardness of these promising candidate alloys have been extensively reported."

the addition of Sb to the Au-Ge eutectic would not only decrease its melting point but would also improve its ductility substantially and the lattice strains induced by the In atoms were the most effective strengthening mechanism