A Drop-in Die-Attach Solution for the High Temperature Lead-Free BiAgX Solder Paste System

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 000058-000065 ◽  
Author(s):  
HongWen Zhang ◽  
Ning-Cheng Lee
Keyword(s):  
Thermal Cycling ◽  
Thermal Aging ◽  
Considerable Increase ◽  
Lead Free ◽  
Solder Paste ◽  
Mixed Powder ◽  
Die Attach ◽  
Alloy Solder ◽  
Dislocation Movement ◽  
High Lead

In the current work, a mixed powder BiAgX solder paste system with the melting temperature above 260°C and comparable, or better, reliability to the high lead-containing solders has been studied. The mixed powder solder paste system is composed of a high-melting first alloy solder powder as a majority and the additive solder powder as a minority. The additive solder is designed to react aggressively with various surface finish materials before, or together with, the melting of the majority solder to form a controllable IMC layer. The IMC layer of the mixed powder system is controllable by the species and quantity of the additive solder, and it is observed to be insensitive to thermal aging and thermal cycling in current tests, while the high lead-containing solders show a considerable increase in IMC layer thickness. Microstructure investigation shows that the fishbone shaped IMC layer interlocks with the bonding interface between solder and components. Both micron-sized and nano-sized Ag-rich precipitations in the joints have been observed to be well distributed in the joint. The exposed Ag-rich particles and the surrounding stepwise pattern in the Bi matrix on the fracture surface indicate that these Ag-rich particles constrain the dislocation movement in Bi matrix, enhancing the strength and the ductility of the joint. Under thermal aging and thermal cycling, both the micron-sized and nano-sized Ag-rich precipitations exhibit only discernible and localized coarsening. The stable interfacial IMC together with the existence of the well-dispersed Ag-rich particles are attributed to the promising reliability in the BiAgX solder paste system.

HIGH RELIABILITY HIGH MELTING LEAD-FREE MIXED BIAGX SOLDER PASTE SYSTEM

2012 ◽  
Vol 2012 (1) ◽  
pp. 000119-000126 ◽  
Author(s):  
HongWen Zhang ◽  
Ning-Cheng Lee
Keyword(s):  
Thermal Cycling ◽  
Thermal Aging ◽  
High Reliability ◽  
Solder Paste ◽  
High Melting ◽  
Mixed Powder ◽  
Alloy Solder ◽  
Dislocation Movement ◽  
Melting Lead ◽  
High Lead

In the current work, a mixed solder powder BiAgX solder paste system with the melting temperature above 260°C and the comparable or even better reliability to the high lead solders has been studied. The mixed solder powder paste system is composed of a high melting first alloy solder powder as majority and the additive solder powder as minority. The additive solder is designed to react aggressively with various surface finish materials before or together with the melting of the majority solder to form a controllable IMC layer. The IMC layer of the mixed powder system is controllable by the species and the quantity of the additive solder and it is observed to be insensitive to thermal aging and thermal cycling in current tests while the high lead ones do show a considerable increase in IMC layer thickness. Microstructure investigation shows the fishbone shape IMC layer interlocks the bonding interface between solder and components. Both micron-sized and nano-sized Ag-rich precipitations in the joints have been observed to be well distributed in the joint. The exposed Ag-rich particles and the surrounding stepwise pattern in Bi matrix on the fracture surface indicate that these Ag-rich particles constrain the dislocation movement in Bi matrix thus enhance the strength and the ductility of the joint. Under thermal aging and thermal cycling, both the micron-sized and nano-sized Ag-rich precipitations exhibit only discernible and localized coarsening. The stable interfacial IMC together with the existence of the well dispersed Ag-rich particles are attributed to the promising reliability in BiAgX solder paste system.

Development of BiAgX® HT Solder Paste for 200°C Application

2016 ◽  
Vol 2016 (HiTEC) ◽  
pp. 000128-000133 ◽  
Author(s):  
Hongwen Zhang ◽  
Jonathan Minter ◽  
Ning-Cheng Lee
Keyword(s):  
Shear Strength ◽  
Thermal Cycling ◽  
Melting Temperature ◽  
Thermal Aging ◽  
Joint Strength ◽  
Solder Paste ◽  
Thermal Cycling Test ◽  
Cycling Test ◽  
Die Attach ◽  
Board Level

Abstract BiAgX® paste with the remelting temperature around 262°C has been tested and adopted successfully for die attach applications [1–5]. BiAgX® HT pastes with the enhanced remelting temperature above 265°C have been designed for the application of 200°C or even higher. The joint strength has been well maintained for most of the tested pastes after thermal aging @ 200°C for 1000hrs. The thermal cycling test (from −55°C to 200°C) degrades the bond shear strength but some of the tested pastes can still keep the joint strength well above IEC standard (IEC 60749-19) required. The melting temperature and the reliability have been observed to closely associate with the alloying elements Z%wt. The BiAgX® pastes have also been modified for board level assembly application. BiAgX® solder wire is under development too.

Thermal Aging Effects on the Thermal Cycling Reliability of Lead-Free Fine Pitch Packages

2013 ◽  
Vol 3 (8) ◽  
pp. 1348-1357 ◽  
Author(s):  
Jiawei Zhang ◽  
Zhou Hai ◽  
Sivasubramanian Thirugnanasambandam ◽  
John L. Evans ◽  
Michael J. Bozack ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Thermal Aging ◽  
Lead Free ◽  
Aging Effects ◽  
Fine Pitch

Perspectives of High-Temperature Pb-Free Bonding Materials

2018 ◽  
Vol 2018 (1) ◽  
pp. 000088-000098
Author(s):  
Hongwen Zhang ◽  
Ning-Cheng Lee
Keyword(s):  
High Temperature ◽  
High Power ◽  
Temperature Cycling ◽  
Processing Temperature ◽  
Potential Candidate ◽  
High Porosity ◽  
Solder Paste ◽  
Material Cost ◽  
Die Attach ◽  
High Lead

Abstract High lead solders have been used as die-attach and interconnect materials in discrete power packages. Due to the demand of SiC devices serving the high-power market and the harmful effects of Pb to human health and the environment, alternative Pb-free solders, novel bonding materials, as well as solutions have been studied extensively in recent years. The exemption of using high-Pb solders has been extended again to 2021, although it could be terminated at any time if a new technology or material were to be accepted by the industry. This paper presents potential materials and technologies for high-temperature Pb-free die-attachment, focusing on alternative solders. Sintering materials and transient liquid phase bonding (TLPB) materials have been briefly covered as well. AuSn, AuSi, and AuGe solders have shown to be exceptionally high in cost, which limited their application. BiAg- and BiCu-based solders—the BiAgX® family including solder paste, solder wire, and solder preform—improved wetting and exhibited remelting temperatures of 262°C and 270°C, respectively. The acceptable reliability performance on temperature cycling and thermal aging, as well as low material cost, has made them the most competitive candidates for low-power discrete die-attach devices. SnSbAgCu, with well-designed compositions in recent studies, offers a remelting temperature above 320°C. SnSbAgCu is targeted in markets for mid-to-high power devices. Reliability testing for other recently designed SnSbAgCu pastes for various die-attach vehicles is being studied. ZnAl has a remelting temperature above 380°C and an extremely low material cost (comparable to or even lower than the high-lead solders). Although the bonding process is stringent, the excellent thermomechanical behavior and the superior thermal/electrical conductivity have allowed ZnAl to be a potential candidate for high-temperature/high-power die-attach that is competitive with AuSi and AuGe solders. Sintering materials form bonds through solid state interdiffusion, while TLPB materials create a joint through solid-liquid interdiffusion, in which the remelting temperature is enhanced by forming massive IMCs. The desired high thermal/electrical/mechanical/melting performances, as well as the relatively low processing temperature (<350°C), are shining the sintering materials (especially Ag-sintering materials). The intrinsic high porosity (>20%) and the evolution of pores from pressureless sintering may overshadow the reliability. In addition, the immaturity of the processing (time/temperature/pressure/atmosphere/equipment availability, etc.) may deter the industrial adoption of sintering materials. So far, none of these materials or technologies is ideal to satisfy all the requirements of the variety of high-temperature, Pb-free die-attach applications in terms of processing, reliability, and cost. However, each material and solution has the potential to be a niche within this broader categorization.

Excellent thermal-cycling stability caused by aging in Fe-doped (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 lead-free piezoceramic

2021 ◽  
Vol 202 ◽  
pp. 113990
Author(s):  
Yanshuang Hao ◽  
Liqiang He ◽  
Shuai Ren ◽  
Yuanchao Ji ◽  
Xiaobing Ren
Keyword(s):  
Thermal Cycling ◽  
Cycling Stability ◽  
Lead Free

scholarly journals Study on the Reliability of Sn–Bi Composite Solder Pastes with Thermosetting Epoxy under Thermal Cycling and Humidity Treatment

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 733
Author(s):  
Lu Liu ◽  
Songbai Xue ◽  
Ruiyang Ni ◽  
Peng Zhang ◽  
Jie Wu
Keyword(s):  
Solder Joint ◽  
Thermal Cycling ◽  
Composite Solder ◽  
Solder Joints ◽  
Solder Paste ◽  
Epoxy System ◽  
Mechanical Reinforcement ◽  
Microstructure Observation ◽  
Temperature And Humidity ◽  
Thermosetting Epoxy

In this study, a Sn–Bi composite solder paste with thermosetting epoxy (TSEP Sn–Bi) was prepared by mixing Sn–Bi solder powder, flux, and epoxy system. The melting characteristics of the Sn–Bi solder alloy and the curing reaction of the epoxy system were measured by differential scanning calorimeter (DSC). A reflow profile was optimized based on the Sn–Bi reflow profile, and the Organic Solderability Preservative (OSP) Cu pad mounted 0603 chip resistor was chosen to reflow soldering and to prepare samples of the corresponding joint. The high temperature and humidity reliability of the solder joints at 85 °C/85% RH (Relative Humidity) for 1000 h and the thermal cycle reliability of the solder joints from −40 °C to 125 °C for 1000 cycles were investigated. Compared to the Sn–Bi solder joint, the TSEP Sn–Bi solder joints had increased reliability. The microstructure observation shows that the epoxy resin curing process did not affect the transformation of the microstructure. The shear force of the TSEP Sn–Bi solder joints after 1000 cycles of thermal cycling test was 1.23–1.35 times higher than the Sn–Bi solder joint and after 1000 h of temperature and humidity tests was 1.14–1.27 times higher than the Sn–Bi solder joint. The fracture analysis indicated that the cured cover layer could still have a mechanical reinforcement to the TSEP Sn–Bi solder joints after these reliability tests.

scholarly journals Eco-Friendly Lead-Free Solder Paste Printing via Laser-Induced Forward Transfer for the Assembly of Ultra-Fine Pitch Electronic Components

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3353
Author(s):  
Marina Makrygianni ◽  
Filimon Zacharatos ◽  
Kostas Andritsos ◽  
Ioannis Theodorakos ◽  
Dimitris Reppas ◽  
...  
Keyword(s):  
High Resolution ◽  
Form Factors ◽  
Circuit Board ◽  
Lead Free ◽  
Process Conditions ◽  
Solder Paste ◽  
Electronic Components ◽  
Successful Operation ◽  
Fine Pitch ◽  
Forward Transfer

Current challenges in printed circuit board (PCB) assembly require high-resolution deposition of ultra-fine pitch components (<0.3 mm and <60 μm respectively), high throughput and compatibility with flexible substrates, which are poorly met by the conventional deposition techniques (e.g., stencil printing). Laser-Induced Forward Transfer (LIFT) constitutes an excellent alternative for assembly of electronic components: it is fully compatible with lead-free soldering materials and offers high-resolution printing of solder paste bumps (<60 μm) and throughput (up to 10,000 pads/s). In this work, the laser-process conditions which allow control over the transfer of solder paste bumps and arrays, with form factors in line with the features of fine pitch PCBs, are investigated. The study of solder paste as a function of donor/receiver gap confirmed that controllable printing of bumps containing many microparticles is feasible for a gap < 100 μm from a donor layer thickness set at 100 and 150 μm. The transfer of solder bumps with resolution < 100 μm and solder micropatterns on different substrates, including PCB and silver pads, have been achieved. Finally, the successful operation of a LED interconnected to a pin connector bonded to a laser-printed solder micro-pattern was demonstrated.

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