Senju Metal Industry to Expand China Solder Operations

Factiva: "Tokyo based major solder maker, Senju Metal Industry expands Chinese operation. The firm expands the integrated operation output capacity from solder alloy to finished products at Huizhou and Beijing in 3 years. The firm also improves the optimization of the production in Chinese operations including paste operations in Shanghai and Hong Kong."

Isotropic conductive adhesives on immersion silver printed-circuit boards

Scopus: "This paper presents the electrical properties of Ag epoxy composite ICAs materials on Cu-finished and immersion-Ag finished PWBs, as solder replacements for SMT or flip chip technologies."

J. Lee, J.E. Morris, Portland State University, US

C.S. Cho, Kyungpook National University, South Korea

IPC Voices Concerns Over RoHS Revision Developments

PCB007: "On the heels of a recent news report that Tetrabromobisphenol A (TBBPA) is on a draft list of substances for priority examination under the European Union's (EU) Restriction of Hazardous Substances (RoHS), IPC President Denny McGuirk dispatched a letter to EU commissioners expressing the organization's concerns for the inclusion of TBBPA."

Nihon Superior patent for precipitating Cu from wave solder baths

Precipitation of copper in lead-free soldering of copper lead wires used for mounting components on printed wiring board, involves adding tin to copper eluted in lead-free soldering and precipitating copper-tin complex.

The purpose of the present invention is to separate excess coppers leached out in a lead-free solder bath and recover tin with high efficiency. An element X (Ni, Co, Fe) for forming a (CuX)6Sn5 compound between copper and tin in molten lead-free solders is added to separate out a (CuX)6Sn5 compound. Tin is recovered by binding the (CuX)6Sn5 compound by passing thereof through a multi-perforated plate, further generating swirling currents to precipitate and separate the bound (CuX)6Sn5 compounds and removing thereof. 

US20080216605, Sept 2008

Indiana Skunkworks Wants to Eliminate Solder

PCB007: "Defense electronics' 20-year reliability requirements rule out the use of l-f solder. Tin whiskers, copper dissolution from printed circuit pads, copper migration into l-f solder, voids, and poor wetting are just some items on the list of l-f hazards that result in shorted or open circuits, even without the help of vibration or shock. The higher melting temperature for l-f solder stresses components and printed circuits, making them less reliable as well. L-f tosses another curve at defense electronics. Use of lower-cost 'commercial off-the shelf' components is constrained because l-f finishes and tin-lead solder are not compatible."

Well-meaning European environmentalists, with help from the tin industry and other self-interest seekers, forced l-f solder on a divided, fragmented, leaderless electronics industry after 1998.

The great irony is that in 2008 problematic l-f solder has inspired a better, cheaper assembly system alternative that eliminates all PCB assembly solder: the Occam Process. If Occam had been universally used in 2008, 9 trillion solder joints would have been replaced by reliable true 3-D blind via interconnects, copper plated, to join component leads to traces. The following discussion will place the new manufacturing structural change in a historical context and discuss the many economic improvements, reliability increases, and environmental benefits.              

Harvey Miller                

International Conference on Lead-Free Electronics to be held December 8–10, 2008

Global SMT & Packaging magazine: "IPC - Association Connecting Electronics Industries and JEDEC Solid State Technology Association today announce an International Conference on Lead-Free Electronics. To be held December 8–10, 2008 at the Fairmont Hotel in Dallas, Texas, the event will feature a full-day technical conference with an outstanding roster of speakers, as well as two full days of informative half-day workshops."

Intel Patent InX Reactive Solder

Intel have patented the use of In with 2% of 'active' rare earth elements such as hafnium, cerium, titanium and lutetium, transition elements such as nickel, copper, iron, and cobalt, and other elements such as magnesium, strontium and cadmium.

 

The solder is for typical use as a solder-based conductive adhesive in die bonding to thermal management devices.  It does not have to use a flux and can bond to non-metallic surfaces.
The patent also mentions SnAg and 'other conventional thermal conductive solder types', although the claims are for indium.

Melting point of In is 156'C so it is not a high temperature option.

Patent

Plans to extend RoHS law out from the shadows

ENDS: Details of legislative plans to extend the EU's 2002 restriction of hazardous substances (RoHS) directive have emerged.  A draft proposal seen by ENDS confirms plans put to public consultation earlier this year.

The proposal was drafted by the European commission's environment department and is currently going through inter-service consultation with other departments pending formal adoption.

The environment department proposes extending RoHS to cover medical devices from 2012.  Industrial monitoring and control instruments would become subject to the rules from 2015.  In vitro diagnostic devices and "active implantable medical devices" should be covered from 2016 and 2020 respectively.

Five new chemicals would be reviewed for possible inclusion on a list of six substances already banned from use in electrical goods under RoHS . These are the brominated flame retardants TBBP-A and HBCDD, and the phthalates DEHP, BBP and DBP.

In future the list should be reviewed in line with the EU's Reach regulation, the environment department says.  Detailed rules for how this will work in practice will be established under the EU comitology procedure, it adds.

A new annex setting out a list of products to be covered by the law is proposed.  The move is designed to more closely align RoHS with a related EU law on waste electrical and electronic equipment (Weee).  This alignment is also proposed in draft legislation to revise the Weee directive.

Other proposals include a requirement for EU member states to carry out market surveillance activities to ensure conformity with the rules.  New "maximum concentration values" for the presence of substances banned under RoHS in "homogeneous materials" are also proposed.

The Influence of an Imposed Current on the Creep of Sn-Ag-Cu Solder

Scopus: "The work reported here included preliminary tests on the influence of an imposed current on the creep rate of the Pb-free solder Sn-Ag-Cu 305 (Sn-3Ag-0.5Cu in wt.%)"

Samples were prepared with three starting microstructures: as cast, thermally aged by long-term isothermal exposure, and current aged by long-term exposure to a fixed current density. The three microstructures were then tested with and without current at two ambient temperatures. The different microstructures had very different creep rates in the absence of current but, surprisingly, imposing a current (5.5 × 103 A/cm2) increased the creep rate by very nearly the same factor (~7×) in every case. Neither of these results is well understood at this time.

University of California, US

Cisco Systems, US

EU governments looking to increase RoHS enforcement

evertiq.com: "Mr. Norlem, Esq. continues: 'EU governments are also looking at more international collaboration with local-RoHS monitoring authorities in China and the United States. Many products sold in Europe are that of companies trading worldwide, so there is scope for more collaboration internationally'. Intertek hosted a forum in which EU and Chinese, and EU and Taiwanese authorities met, respectively, in Shanghai and Taipei on November 16 and 19, 2007 to present and discuss this. A further forum is being organized for February 2009 with California’s DTSC."

Executive's Guide to Environmental Megatrends that will Shape the Future of the Electronics

Research and Markets: "This 67-page guide was written by Dr. Paul Goodman of ERA Technology, one of the world's leading consultancies on environmental trends with expertise in the electronics industry. IPC commissioned this study to help electronics executives steer their companies through the increasingly costly and complex landscape of worldwide environmental requirements. Three major environmental trends are the focus of the report. It covers future substance restrictions, including new substances that may be restricted by RoHS and the new REACH regulation restricting an estimated 30,000 chemical substances. It also forecasts the impact of energy efficiency and end-of-life recycling requirements and trends. Published September 2008."

Conductive adhesive could replace solder

EETimes.com: "Researchers have invented a nanotube-based dry adhesive that they propose using instead of solder to assemble components on circuit boards. The adhesive, which has very high electrical and thermal conductivity, models its sticking power on the foot of the gecko lizard. It works without heat or solvents, permitting use in the vacuum environments used to make chips and in space."

Limin Dai, Liangti Qu, University of Dayton, Ohio

Zhenhai Xia, University of Akron

Zhong Lin Wang, Georgia Institute of Technology

Morley Stone, Air Force Research Laboratory

See also:

ASI (Adhesives & Sealants Industry), 21/10/08

Japan Automotive to be lead-free by 2009

Kay Nimmo, ITRI, 04/05/08

The japanese automotive industry have required suppliers of electronics to be Pb-free by 2009

Market data: Potential tin use in High-Lead High Temperature Solders

Kay Nimmo, ITRI, 04/05/08

The Japanese estimate of use of high Pb solder (i.e. 95%Pb) in japan is actually a third of total Pb use (in 2000 statistics) and therefore around 11,000tpa. They think that half of this can be replaced in 2-3 years. 

Correction: Japan use 2000 = 2,500 tpa, extrapolating to 11,000 tpa Sn90Pb worldwide

Otmar Deubzer, Fraunhofer-IZM, 17/09/08

The total amount of high melting point solders in electronics is around 11,000 t per year. This refers to HMP solders with high lead content. The figures go back to a detailed interview with Senju Metals in Japan. However, the data are from 2000. I do not have more current ones, and I have never found another source indicating the amount of HMP solders used in electronics. 

I do not have the exact range of lead content in these HMP solders. 

The influence of low level doping of Ni on the microstructure and reliability of SAC solder joint

Scopus: "Both solder composition and PCB surface finish had a notable effect on the interfacial microstructare, the Ni addition can give rise to needle like NiCuSn IMC formation and reduce the grain size locally at solder/NiAu pad interface after one time reflow according to top-view interface analysis, and had no obvious effect on the IMC evolution of solder/OSP pad," It was found that the decrease of Ag concentration and Ni addition in SAC solder could significantly improve the drop test performance when NiAu pad was used. In bending test, OSP pad show better performance than Au/Ni pad. The correlation between joint microstructare and joint reliability was discussed in detail.

Samsung

Effects of Ni addition on microstructure and the shear strength of Sn-3.0Ag-0.5Cu/Cu solders joints

Scopus: "The results indicate that the addition of Ni element increases the shear strength of solder joint. When the content of Ni is 0.10 wt. %, the shear strength of solder joint is the highest by 40.28MPa which is 18% higher than that of Sn-3.0Ag-0.5Cu lead-free solder. The fracture morphology shows that the addition of Ni promotes grain refinement which leads to the increase of shear strength. The shear strength of the solder joints decrease continuously. The fracture microstructare became coarse-rained with the increase of thermal aging time."

Harbin University, China

Suppressing intermetallic compound growth in SnAgCu solder joints with addition of CNTs

Scopus: "Results revealed that after soldering, the initial interfacial IMC thickness of the unreinforced solder joint was comparable to that of the composite solder joints. However, after aging, the interfacial IMC layer of the unreinforced solder joint was observed to grow more significantly than that of the composite solder joints. Furthermore, the composite solder joints exhibited lower diffusion coefficient"

University of Singapore

Solder joint reliability of different BGAs reworked using low melting point Pb-free alloys

Scopus: "Solder joint reliability of different BGA's reworked using low melting point Pb-free alloys was investigated." The CSP 46 component was removed and a new component was placed using low-melt In-containing alloy A

Celestica

Matsushita Use Bubbles for Solder Self-Assembly

Matushita have developed a novel self-assembly technique for soldering using a bubble-generating reagent during heating to 'herd' solder particles towards electrodes, eliminating bridging and cutting process time.

The work was presented at the September 2008 IMAPS Nordic meeting in Denmark.

The SASB (Self Assembling Solder Bonding) technique disperses a solder paste containing solder particles and the reagent across the whole interconnection region between two boards or a board and component. In the heating process, the bubbles cause the solder particles to migrate to the interconnection space between opposite electrodes, where they can then be melted to form the multiple solder joints. The resin is also cured, meaning that no additional underfill operation is needed.

Matsushita have successfully used the technique for 100um pitch board-to-board connections for flexible printed circuits (FPCs), without bridging and with good reliability.

To obtain a copy of the paper, apply to the IMAPS Nordic office for the CD of proceedings.

The effect of Ni nanoparticles addition on shear behavior and microstructure

Scopus: "The result shows that adding nickel nanoparticles can improve the shear performance of the soldered joint; the shear force of the soldered joint is highest when adding 0.5wt% Ni nanoparticles at reflow 240s. The SEM observations shows that the hexagonal Cu6Sn5 IMC (intermetallic compound) in the inside solder is disappears gradually and the morphsa of the IMC that on the interface of the solder joint becomes planar after adding Ni nanoparticles into solder"

Shijiazhuang Railway Institute, China

Reliability Prediction for Different Sn-based Solders

Scopus: "Recent studies revealed that there is no simple 'drop in' solution for the lead-free replacement of SnPb joints, instead different Sn-based solders are advantageous for different use conditions, which can be dominated either by drop loading or by thermal cyclic loading in harsh use conditions. By way of high-speed shear testing reliability assessments of components during drop and shock events can be studied in a simplified manner. Dynamic 3-D finite element simulations have been performed applying explicit FEA to replicate the shear tests virtually. It was shown in this way that SAC 1305 solder outperformed SAC 387 solder. The low cycle fatigue behavior of different SAC alloys is additionally of interest."

Rainer Dudek, Fraunhofer IZM, Germany

Sn-Ag-Cu-Mg Lead-Free Solders

Scopus: "The results indicate that Mg, combined with the other alloying elements Ag and Cu, plays a key role in modifying the melting characteristics of the alloy solders. And with the added Mg, the wettability of solders is depressed."

REACH Impact on Electronics Greater Than RoHS

Factiva: "It has been estimated that the financial impact on electronics manufacturers of Reach will be 12 times greater than that of RoHS, which covers a narrow scope of substances in electronic products comprising about 100 different chemicals. This contrasts with Reach, which will cover about 30,000 unique chemicals."

Shear fracture behavior of SAC solder joints on Cu pads with different solder volumes

Scopus: "To meet the urgent demands of future electronic packages, the solder joints have to become increasingly miniaturized. Compared to the large solder joints, mechanics behavior for the small solder joints is very different, resulting in a series of reliability issues. The results show that shear strength of the solder joint increases with the decreasing of the solder joints volumes. For the large volume solder joints, the fracture occurs close to the interface, and the solder joint shows strong brittleness. Whereas, for the small solder joints, the fracture occurs within the bulk solder, and the solder joint shows ductile property."

Harbin Institute of Technology, China

Samsung China

Backward compatibility of solder joints under thermal cycle

Scopus: "In this paper, the backward compatibility solder joints were chosen in simulation of perimeter PBGA272 assembly. On the basis of above analysis, the geometry parameters of the chosen assembly are optimized by design of experiment (DOE). The factors included PCB size, PCB thickness, chip size, chip thickness, substrate size, substrate thickness, solder height and solder radius."

Guilin University, China

Reaction of Sn-10Sb-5Cu high temperature lead-free solder and Cu substrate

Scopus: "Sn-Sb alloys are potential solders for replacement of high-Pb solders because of their high melting temperature in lead-free solders. However, Cu substrate is extremely dissolved by the Sn-Sb binary alloy during the high temperature soldering process, which will cause serious reliability problem of the solder joint. Based on this critical issue, we designed a new high temperature lead-free Sn-10Sb-5Cu ternary solder to prevent the dissolution of Cu substrate"

Zhejiang Metallurgical Research Institute, China

Zhejiang University, China

Manufacture of Hourglass-Shaped Solder Joints

Scopus: "Induction heating reflow method, which can achieve the solder bumping and interconnecting process in a simple way, was studied to control the height and shape of solder interconnects employed in electronic packaging application. In this work, the barrel-shaped solder joints with high heights and the hourglass-shaped solder joints can be obtained which is useful to increase the solder joint lifetime."

Harbin Institute, China

Jeonnam Provincial College, South Korea

Effect of Shear Rate on Lead-Free Solder Joint Strength

Scopus: "Solder joint strength at high strain rates is a critical reliability requirement for portable electronic devices. Experimental observations showed low shear rate tests of solder joints cannot be used to accurately predict the mode of deformation and failure behaviors under high speed impact condition. Due to strain rate effect, brittle failure of solder joints under dynamic loadings may not take place at low strain rates. Thus, characterization of solder joints under impact becomes critical in package design and manufacturing for high reliability. This is particularly true for lead-free solder in handholds 

Hong Kong University, AMD Canada

Silver nanosintering: A lead-free alternative to soldering

Scopus: "We propose a lead-free silver paste as a replacement for a high-temperature lead-rich solder used for electronics. The pastes tested here contain a small amount of solvent, but primarily consist of silver powder and alkoxide-passivated silver nanoparticles that undergo nanosintering when heated. The pastes were used to connect silicon diode chips to copper bases at 350'C in nitrogen ambient without external pressure. The resulting diode packages had electrical and thermal properties about equal to those with lead-solder joints. The mechanical strengths also were comparable to the lead joint. These properties make this nanosilver paste the first viable lead-free alternative to a lead solder."

Maruyama, Osaka University