A novel high melting lead-free mixed solder paste system

2011 ◽  
Author(s):  
HongWen Zhang ◽  
Ning-Cheng Lee
Keyword(s):  
Lead Free ◽  
Solder Paste ◽  
High Melting ◽  
Melting Lead

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.

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.

Quantitative Evaluation of Voids in Lead Free Solder Joints

2015 ◽  
Vol 772 ◽  
pp. 284-289 ◽  
Author(s):  
Sabuj Mallik ◽  
Jude Njoku ◽  
Gabriel Takyi
Keyword(s):  
Solder Bump ◽  
Solder Joints ◽  
Void Formation ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
X Ray ◽  
Size And Shape ◽  
Solder Bumps ◽  
Free Solder

Voiding in solder joints poses a serious reliability concern for electronic products. The aim of this research was to quantify the void formation in lead-free solder joints through X-ray inspections. Experiments were designed to investigate how void formation is affected by solder bump size and shape, differences in reflow time and temperature, and differences in solder paste formulation. Four different lead-free solder paste samples were used to produce solder bumps on a number of test boards, using surface mount reflow soldering process. Using an advanced X-ray inspection system void percentages were measured for three different size and shape solder bumps. Results indicate that the voiding in solder joint is strongly influenced by solder bump size and shape, with voids found to have increased when bump size decreased. A longer soaking period during reflow stage has negatively affectedsolder voids. Voiding was also accelerated with smaller solder particles in solder paste.

Study of a Low Cost Reballing of BGA Method with Lead-Free Solder Paste

2019 ◽  
Vol 14 (1) ◽  
pp. 651-657
Author(s):  
Talita Mazon ◽  
Guilherme E. Prevedel ◽  
Egont A. Schenkel ◽  
Marcio T. Biasoli
Keyword(s):  
Low Cost ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Free Solder
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