TIN/TIN ALLOY NANOPARTICLE HAVING LOW MELTING TEMPERATURE AND METHOD FOR MANUFACTURING SAME

Disclosed are a nanoparticle having a size of 1-20nm prepared by electrolyzing a tin or a tin alloy, and a method for preparing same. The nanoparticle surface-melts in a temperature range of 80-130?. A solder ball having the nanoparticle can be sintered at or below 160?, and can thus, first, save 22% of energy by resolving the energy consumption of 74 kW for the conventionally used reflow processing device to an energy consumption of 50 kW by enabling the heating temperature to be lowered from 240? to 160? during reflow process. Second, deformation of a PCB board can be minimized by enabling the temperature for the reflow process to be lowered, and application areas for implementation materials having a low unit cost can be created by enabling the use of low cost polymer materials such as PET having low glass transition temperature. And third, the uniformity of a solder paste on a pad can be enhance when using a nanoparticle having a size of 10 nm or smaller, and in the case of a nano-solder ink, the limitations of micro-patterning can be overcome due to the small size of the particle (Figure 4).



WO2012096489  (A2)  -  TIN/TIN ALLOY NANOPARTICLE HAVING LOW MELTING TEMPERATURE AND METHOD FOR MANUFACTURING SAME
Inventor(s): KIM YOUNG SANG [KR] +
Applicant(s): ISP CO LTD [KR]; KIM YOUNG SANG [KR]; CHO KYUNG JIN [KR]; JANG SEOK PIL [KR]; LEE JONG HYUN [KR]; KIM HYUN SOO [KR] +
Classification:
- international: B22F1/00; B23K35/26; C25C5/02
- European:
Application number: WO2012KR00223 20120110 
Priority number(s): KR20110002482 20110110

An Investigation into Low Temperature Tin-bismuth and Tin-bismuth-silver Lead-free Alloy Solder Pastes

IPC: An Investigation into Low Temperature Tin-bismuth and Tin-bismuth-silver Lead-free Alloy Solder Pastes
Presentation by Jasmir Bath of Christopher Associates

This presentation was recorded live in San Diego, California during the Technical Conference at IPC APEX EXPO on February 28, 2012
Total run time of presentation: 17 minutes, 33 seconds

Mr. Jasbir Bath is a Consulting Engineer for Christopher Associates/Koki Solder in the Americas. He is an INEMI Consultant working on the INEMI lead-free rework optimization project.

Bath is also the owner of Bath Technical Consultancy which provides consulting and training services in the electronics manufacturing industry. Previously, he was the Corporate Lead Engineer with Solectron Corporation and Flextronics International for 10 years with a role involving tin-lead and lead-free solder process development.

Mechanical strength and fracture mode transition of Sn-58Bi epoxy solder joints under high-speed shear test

Scopus The shear force and failure behaviors of the Sn-58Bi epoxy solder joints with various surface finishes under the high-speed shear test were investigated. The relationships between the shear speed, shear force, and fracture mode are elucidated in this study. The shear force of the Sn-58Bi solder joints increased with increasing shear speed, mainly due to the high strain-rate sensitivity of the solder alloys. Brittle interfacial fractures were more easily achieved at higher shear speed in the high-speed shear test. This result was discussed in terms of the relationship between the strain-rate of the solder alloy, the work-hardening effect, and the resulting stress concentration in the interfacial regions. The fracture mode changed from ductile solder fracture to brittle interfacial fracture with increasing shear speed. On the other hand, the different surface finish materials did not affect the shear force and fracture mode of the Sn-58Bi solder joints under high-speed shear loading

Journal of Materials Science: Materials in Electronics
2012, Pages 1-6
Mechanical strength and fracture mode transition of Sn-58Bi epoxy solder joints under high-speed shear test  ( Articles not published yet, but available online Article in press About articles in press (opens in a new window) )

Cho, I.a,Ahn, J.-H.b,Yoon, J.-W.b,Shin, Y.-E.c ,Jung, S.-B.b  

a  Productivity Research Institute, LG Electronics Inc., 19-1, Cheongho-ri, Jinwi-myeon, Pyeongtaek-si, 451-713, South Korea
b  School of Advanced Materials Science and Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, 440-746, South Korea
c  School of Mechanical Engineering, Chung-Ang University, 221 Heuksuk-dong, Dongjak-gu, 156-756, South Korea

Chemo-rheological characteristics of a self-assembling anisotropic conductive adhesive system containing a low-melting point solder

ScienceDirect.comTo achieve the excellent wettability of a solder in an anisotropic conductive adhesive (ACA) in micro-packaging technology, not only the removal of the oxidized layer of the solder but also the chemo-rheological phenomena of the thermally induced self assembly of low-melting temperature solder powders were investigated for ACA applications. Both the optimum kind and amount of reductant were determined in this study to remove the oxidized layer formed on the solder surface in ambient environment. The solder wetting test was performed to observe the chemical and rheological compatibility between the solder, polymer matrix, and reductant. The thermal analysis was done using differential scanning calorimetry (DSC) analysis and rheometer test. Several chemical reactions by the reductant were proposed, and the mechanisms were postulated. It is believed that the reductant reacts with the oxidized layer, amine, and epoxide group, respectively. The relation between conversion and glass transition temperature of the polymer matrix was also obtained from DSC.


Microelectronic Engineering
Volume 87, Issue 10, October 2010, Pages 1968–1972
Chemo-rheological characteristics of a self-assembling anisotropic conductive adhesive system containing a low-melting point solder ☆
Ji-Won Baeka, b, Keon-Soo Janga, b, Yong-Sung Eoma, , , Jong-Tae Moona, Jong-Min Kimc, Jae-Do Namb, , 
a Next Generation Packaging Team, Electronics and Telecommunications Research Institute, 161 Gajeong-dong, Yuseong-gu, Daejeon 305-700, Republic of Korea
b Department of Polymer Science and Engineering, Sungkyunkwan University, Suwon, Republic of Korea
c Department of Mechanical Engineering, ChungAng University, Seoul, Republic of Korea
Received 23 July 2009. Revised 2 November 2009. Accepted 7 December 2009. Available online 29 December 2009

Properties of solders with low melting point

ScienceDirect.com: The aim of the work is to analyse thermal properties and microstructure of solders, which should be suitable for application in electronics.

The solders must have low enough working temperature to avoid thermal damage of the assembly and uniform microstructure in whole bulk. For solders presented in this work the required temperatures are less than 150 °C. They represent alternative, for example, to the conductive adhesives, which are in use. Five types of solders have been studied. They were created from the metals: Sn, In, Bi, Cd. The solder on the basis of Bi/Sn, has the composition of 58 wt.% Bi and 42 wt.% Sn of eutectic point of the alloy and the melting point of 141 °C. The second solder of the composition of 53 wt.% Bi, 26 wt.% Sn and 21 wt.% Cd proved the melting temperature of 103 °C. The next both solders are on Sn/In basis. The solder with composition of 70 wt.% In and 30 wt.% Sn has the melting point temperature of 126 °C. The second solder of nearly eutectic composition, 50 wt.% Sn and 50 wt.% In has lower melting temperatures about 117 °C. The last one is ternary solder with composition of 53 wt.% Sn, 37 wt.% Bi and 10 wt.% In with the melting point between 100 and 123 °C. Differential scanning calorimetry (DSC) was used to determine the thermal properties of these solders. For the study of microstructure light microscopy and X-ray diffraction analysis were used. The analysis of solders microstructure show that almost all solders have homogenous distribution of two or three phases in the microstructure.


Journal of Alloys and Compounds
Volume 457, Issues 1–2, 12 June 2008, Pages 323–328
Janka Chriašteľová, , Milan Ožvold
Department of Materials Engineering, Faculty of Materials Science and Technology, Slovak University of Technology, Paulínska 16, 917 24 Trnava, Slovak Republic


Received 28 January 2007. Revised 13 March 2007. Accepted 14 March 2007. Available online 19 March 2007.

EU consultant draft recommendation on ELV windscreen exemption

EU consultant Okopol has drafted a recommendation that the End of Life Vehicle Directive exemption for lead solders used in windscreens be removed.

Possible 3-year extension:


"In case the Commission grants the OEMs additional time, the consultants suggest the following wording for exemption 8 (i):
Lead in solders in electrical glazing applications on glass, except for soldering in laminated glazing, in vehicles type approved before 1 January 2015, and lead in spare parts for these vehicles."


The report has some revealing insights into development and properties of indium lead-free solders.

ACEA representing the car industry argued that indium solders melt at too low temperature and sunlight etc will melt them. However, it seems to depend on how this is measured. Some indium solders are already used in the industry for some years with no evidence of failure.

However, indium is on the list of critical materials.

In fact this is a very small market - only about 15 tonnes maximum (?in Europe) and probably less.

It also says the St Gobain are developing bismuth-based low temperature solders by end-2012.

Report

Related story

Pulse electroplating of Sn-Bi alloys on micropatterned electrodes for lead-free solder bumping

Scopus: Pulse plating of Sn-Bi alloys was performed in a simple binary Sn 2 -Bi 3 bath containing citric acid (CA), ethylenediaminetetraacetic acid (EDTA), and poly- ethylene glycol (PEG400) at pH = 1 under 70 of duty percentage and 10 Hz of pulse frequency on polyimide-micropatterned CuNi substrates (denoted as mPI-CN).

From the chronopotentiometric and scanning electron microscopic (SEM) studies, the edge effect of mass transport for Bi 3 resulted in the composition variation between edge and central regions. The increase in the Sn content of Sn-Bi deposits reduces the dendrite formation in the edge region. Through adjusting the concentration of Bi 3 ions and the current density of pulse deposition, uniform morphologies and compositions of Sn-Bi deposits could be obtained. From the demonstration shown in this work, the pulse plating method provided a reliable route to obtain uniform Sn-Bi alloys of high Sn contents (e.g., 80Sn-20Bi and 90Sn-10Bi) for the micro-sized lead-free solder bumping

Tsai, Y.-D., Yu, C.-Y., Hu, C.-C. , Duh, J.-G.

Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu 30013, Taiwan

Journal of the Electrochemical Society
Volume 159, Issue 2, 2012, Pages D108-D113

Bi-Al-Zn-BASED Pb-FREE SOLDER ALLOY

WO2011158668 Disclosed is a Pb-free solder alloy with low residual stress at solidification and high bonding strength and reliability, that can suppress Ni-Bi reaction and Ni diffusion when an electronic component that includes Ni and a substrate are bonded, and that can withstand high reflow temperatures. A first Pb-free solder alloy contains 0.03% to 0.70% by mass Al and 0.2% to 14.0% by mass Zn, and the balance, excluding unavoidable impurities, is formed from Bi. A second Pb-free solder alloy contains 0.03% to 0.70% by mass Al and 0.2% to 14.0% by mass Zn, does not contain more than 0.500% by mass P, and the balance, excluding unavoidable impurities, is formed from Bi.

ISEKI Takashi; Japan 〒19

 Assignee: SUMITOMO METAL MINING CO., LTD. Japan〒10
 News, Profiles, Stocks and More about this company

 Published / Filed: 2011-12-22 / 2011-06-03

 Application Number: WO2011JP0062792

Effect of Bismuth on Intermetallic Compound Growth in Lead Free Solder/Cu Microelectronic Interconnect

Scopus: The intermetallic compound (IMC) growth kinetics in pure Sn/Cu and Sn10 wt%Bi/Cu solder joints was studied, respectively, after they were aged at 160-210'C for different time.

It was found that the total IMC in SnlO wt%Bi/Cu joint developed faster than it did in pure Sn/Cu solder joint, when they were aged at the same temperature. And the activation energy Qa for total IMC in Sn10 wt%Bi/Cu joint was lower than that for pure Sn/Cu interconnect. The IMC growth process was discussed. The IMC Cu6Sn5 was enhanced in compensation of reduced IMC Cu3Sn growth.

The work reveals that Bi element containing in lead free solder alloys with 10 wt% can enhance IMC growth in lead free solder/Cu joint during service

Kang, T.Y.a , Xiu, Y.Y.b , Hui, L.b , Wang, J.J.b , Tong, W.P.a , Liu, C.Z.b

a Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110004, China

b Shenyang Aerospace University, Shenyang 110136, China

Effect of microelements on Sn-20Bi solder

Scopus: Adding microelements Ag In Ga and Sb into Sn-20Bi solder, the changes of melting properties and microstructures of the solder were observed.

The experimental result showed that when the content of Ag was 0.7% (wt%), In was 0.1% , Ga was 0.5% and Sb was 0.5%, the melting points of the solder reduced to the bottom and the segregation of Bi obviously decreased. Sb was not suitable to add solely but when it was added together with Ag In and Ga, it can produce a good effect on reinforcement of solid solution, furthermore it can restrain the phase change of Sn.

The Sn-Bi-X solder with the best compositions of Ag In Ga and Sb has a near melting point to Sn-37Pb. The solder is close to practicality without segregation of Bi


Li, Y., Luo, Y., Chen, X. 
School of Computer, National University of Defense Technology, Changsha, 410073, China

Drivers for low temperature solders, high temperature solders

From visit to Alpha Cookson June 2011

There are a few driving forces behind it.

1. No silver (generally)

2. Lower processing costs due to lower temperatures

a. Lower energy consumption

b. Cheaper materials used for equipment as they tend to be less aggressive

c. Cheaper heating solutions

3. Allows use of cheaper components, laminates etc

4. Big expansion in use of substrates and components which cannot tolerate higher temperatures

a. OLEDs and other displays

b. Flexible electronics

c. ……..

5. Using a low temperature solder could solve some problems in finding a high temperature solder because you could shift everything down a level so don’t need to develop/use a HT lead-containing alternative

Taiwan SnBiCe whiskers?

Factiva: "According to a study from Taipei, Taiwan, 'The effects of a rare-earth element on the microstructure, mechanical properties, and whisker growth of Sn-58Bi alloys and solder joints in ball grid array (BGA) packages with Ag/Cu pads have been investigated. Mechanical testing indicated that the elongation of Sn-58Bi alloys doped with Ce increased significantly, and the tensile strength decreased slightly, in comparison with undoped Sn-58Bi.'

'In addition, the growth of both fiber- and hillock-shaped tin whiskers on the surface of Sn-58Bi-0.5Ce was retarded in the case of Sn-3Ag-0.5Cu-0.5Ce alloys. The growth of interfacial intermetallic compounds (IMC) in Sn-58Bi-0.5Ce solder joints was slower than that in Sn-58Bi because the activity of Ce atoms at the interface of the Cu6Sn5 IMC/solder was reduced. The reflowed Sn-58Bi and Sn-58Bi-0.5Ce BGA packages with Ag/Cu pads had a ball shear strength of 7.91 N and 7.64 N, which decreased to about 7.13 N and 6.87 N after aging at 100 degrees C for 1000 h, respectively,' wrote T.H. Chuang and colleagues, National Taiwan University.

The researchers concluded: 'The reflowed and aged solder joints fractured across the solder balls with ductile characteristics after ball shear tests."

T.H. Chuang, National Taiwan University, Institute Materials Science & Engineering, Taipei 106, TAIWAN.

Low Tm Solder HP

Low Tm Solder: "The application of low-temperature solders in surface mount assembly processes for products that do not experience harshtemperature environments is technically feasible. Low-temperature assembly appears promising as an addition to the surfacemount landscape as a way of increasing process flexibility and component reliability.

However, one single alloy won’t be auniversal solution. Specific component and assembly requirements will have to be considered in choosing or tailoring thebest solder alloy for each application."

Advantages of Bismuth-Based Alloys for Low-Temperature Lead-Free Soldering and Rework

EMS007: "The increased function of personal electronic devices, such as mobile phones and personal music devices, has driven the need for smaller and smaller active and passive components."

This trend toward miniaturization, occurring at the same time as the conversion to RoHS-compliant lead-free assembly, has been a considerable challenge to the electronics assembly industry. The main reason for this is the higher reflow process temperatures required for lead-free assembly. These higher temperatures can thermally damage the PCB and the components. In addition, the higher reflow temperatures can negatively affect the solder joint quality, especially when coupled with the smaller paste deposits required for these smaller components. If additional thermal processing is required, the risk increases even more.

A low-temperature solder is advantageous in this process in that its lower temperature thermal processing requirements can reduce the total thermal damage caused by using higher melting temperature alloys. Defects, such as delamination or "popcorning" of moisture sensitive devices (MSD), could be minimized or eliminated by using lower temperature solders. Delamination or popcorning failure modes occur when moisture diffuses into plastic components that rapidly expand upon heating. These lower temperature alloys may also be considered for use with temperature sensitive components, the step soldering process or rework.

OM520 SnBiAg study

Scopus: "The compliancy with RoHS directives as well as the trend towards green technologies and green processes has been the main driver for the paste manufacturers. One direction that has proven to be worth while exploring is the one towards low melting point alloys that will enable energy savings during the manufacturing processes. Last but not least these emerging alloys will add an extra benefit to the economy of the production process, the elimination of wave soldering process. The solder paste used: OM520, 42%Sn/57.6% Bi/0.4%Ag, type 3 powder by IPC J-STD-005 [7], the study was completed on a FR2 PCB with OSP finish. A SAC305 paste - OM338PT, SAC305, type 3 powder by IPC J-STD-005 [8] - was used as benchmark for the measurements."

Cucu, T.C., Plotog, I., Svasta, P., Branzei, M.

Politehnica University of Bucharest, Romania

Alpha Announces Global Licensing Agreement with Alcatel Lucent for SnBiAg Lead-Free

Factiva: "Alpha announces that it has established a licensing agreement with Alcatel Lucent to complete Alpha’s suite of global sub-licenses required to offer SnBiAg low temperature solder paste to the global Electronics Assembly Market.

‘Cookson Electronics is a strong supporter of Intellectual Property rights for both our internally developed technologies, and for technologies developed by others,’ said Bruce Moloznik, Alpha’s VP - Global Marketing & Corporate Development. ‘Alpha’s recent agreement with Alcatel Lucent completes our global patent access to the SnBiAg alloy technology and its associated global IP landscape.’

Alpha has engineered its CVP-520 SnBiAg lead-free solder paste based on this intellectual property and will continue to utilize the SnBiAg alloy in the development of other soldering products that will produce electronic joints with higher reliability than those produced using eutectic SnBi alloys. With this increased reliability, Alpha’s SnBiAg products will enable the use of a low temperature second-side reflow process that can eliminate wave soldering of many multi-technology electronic assemblies that still require wave soldered joints.

With the higher reliability of Alpha’s CVP-520 SnBiAg solder paste over eutectic SnBi pastes, many electronics assemblers may also be able to take advantage of lower energy and material costs enabled by a 20% lower reflows peak temperature versus traditional SAC 305 processes."

Christopher Associates Debuts Koki SB6N58-A730

EMS007: "Christopher Associates announced today the introduction of Koki's SB6N58-A730 low temperature lead-free solder paste. SB6N58-A730 paste has a melting point of 201-210C. The paste also demonstrates extremely high thermal shock durability.

SB6N58-A730 contains 6% Indium while still achieving low structural transformation. Indium additions lower melting points when compared to SnAgCu alloys such as SAC305. This lower reflow temperature is desirable for PCBs."

S-Bond patent on active low temperature solders

United States Patent: 7806994: "Electronic package formed using low-temperature active solder including indium, bismuth, and/or cadmium

Abstract
An active solder alloy, an electronic device package including the active solder alloy bonding an electronic device to a substrate, and a method of forming high-strength joints by soldering using the solder alloy. The alloy contains up to about 10% by weight of an element or a mixture of elements selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, or tantalum; between about 0.1 and 5% by weight of an element or a mixture of elements selected from the group of the lanthanides (rare earths); between about 0.01 and 1% by weight of gallium up to about 10% by weight of silver; up to about 2% by weight of magnesium; and a remainder consisting of tin, bismuth, indium, cadmium, or a mixture of two or more of these elements. The alloy enables low-temperature (less than about 180.degree. C.) soldering within relatively narrow melting ranges (less than about 10.degree. C.).

Inventors: Smith; Ronald W. (Blue Bell, PA), Redd; Randall (Phoenixville, PA)
Assignee: S-Bond Technologies, LLC (Lansdale, PA)
Appl. No.: 11/579,413
Filed: May 4, 2005"

Cu alloy, Bi powder low temperature lead-free solder

Factiva: "Provided is a metal filler comprising a mixture of first metal particles with second metal particles, wherein the first metal particles are Cu-alloy particles containing Cu as the major component, which is an element being present at the highest ratio by mass, together with In and Sn; the second metal particles are Bi-alloy particles containing 40-70% by mass of Bi together with 30-60% by mass of one or more metals selected from among Ag, Cu, In and Sn; and the content of the second metal particles is 40-300 parts by mass per 100 parts by mass of the first metal particles. Also provided are a lead-free solder containing the aforesaid metal filler, a bonded structure formed by using the aforesaid lead-free solder, and a substrate to which a part provided with the aforesaid bonded structure is mounted"


 Publication No. WO/2010/098357 was published on Sept. 02.


Title of the invention: "METAL FILLER, LOW-TEMPERATURE-BONDING LEAD-FREE SOLDER AND BONDED STRUCTURE."


Applicants: Asahi Kasei E-materials Corporation (JP).


Inventors: Tomonori Kiyama (JP) and Norihito Tanaka (JP)

Low temperature solder by quenching

Patent application: "The inventors have focused on a fact that a quenching process can produce an Sn solid solution which cannot exist from the viewpoint of an equilibrium diagram. Specifically, a Sn--Cu based alloy is produced by using metal Cu exhibiting an intermetallic compound Cu.sub.5Sn.sub.5 having a melting point not less than a reflow temperature at a position adjacent to Sn in the equilibrium diagram. In the case of using a method other than the quenching process, this alloy results in a two-phase structure of Sn and a Cu.sub.5Sn.sub.5 intermetallic compound in a ratio according to the equilibrium diagram depending on the Cu content."

However, it has been unexpectedly found that, when an alloy is produced by a quenching process such as an atomizing method or a melt-span method, Cu which should intrinsically form a Cu.sub.6Sn.sub.5 intermetallic compound is forcibly dissolved into the Sn to result in a phase similar to that of Sn as a Sn solid solution and therefore, in the quenched alloy, the amount of the Cu.sub.6Sn.sub.5 intermetallic compound being a high-melting-point phase is significantly reduced as compared to the theoretical amount calculated from the ratio between Sn and Cu in the alloy. In contrast, it has also been found that, since the Sn phase contributing to soldering exists as a Sn solid solution phase, its content is significantly increased as compared to the theoretical amount.

From these findings, the inventors have further found that the alloy produced through the above quenching process is mostly composed of a Sn solid solution phase and, if the alloy in this state is used for soldering as a solder material and is then cooled in a normal way, there is formed a solid state of an alloy that is prepared by using a method other than the quenching process.

This enables soldering on a temperature condition of a relatively low temperature (about 230.degree. C.), and the solder can retain a good solid state even at a high temperature (about 400.degree. C. or more) due to existence of the Cu.sub.6Sn.sub.5 phase.

Inventors: Hiroki Ikeda Katsu Yanagimoto Noriaki Matsubara

Agents: THE WEBB LAW FIRM, P.C.

Assignees: SANYO SPECIAL STEEL CO., LTD.

Origin: PITTSBURGH, PA US

IPC8 Class: AB23K3524FI

USPC Class: 148 22

Patent application number: 20100089498