Electrical characteristics of fine pitch flip chip solder joints fabricated using low temperature solders

2004 ◽  
Author(s):  
Un-Byoung Kang ◽  
Young-Ho Kim
Keyword(s):  
Low Temperature ◽  
Flip Chip ◽  
Solder Joints ◽  
Electrical Characteristics ◽  
Fine Pitch

Corrections to "Ultra-fine pitch stencil printing for a low cost and low temperature flip-chip assembly process"

2007 ◽  
Vol 30 (2) ◽  
pp. 359-359
Author(s):  
Robert W. Kay ◽  
Stoyan Stoyanov ◽  
Greg P. Glinski ◽  
Chris Bailey ◽  
Marc P. Y. Desmulliez
Keyword(s):  
Low Temperature ◽  
Flip Chip ◽  
Low Cost ◽  
Assembly Process ◽  
Stencil Printing ◽  
Fine Pitch ◽  
Flip Chip Assembly

Flip Chip Joining with Quaternary Low Melting Temperature Solder Bump Fabricated with Injection Molded Solder

2019 ◽  
Vol 2019 (1) ◽  
pp. 000103-000109 ◽  
Author(s):  
Takashi Hisada ◽  
Toyohiro Aoki ◽  
Eiji Nakamura ◽  
Sayuri Kohara ◽  
Hiroyuki Mori
Keyword(s):  
Thermal Cycling ◽  
Flip Chip ◽  
Solder Joints ◽  
Quaternary Alloy ◽  
Thermal Cycling Test ◽  
Sac305 Solder ◽  
Cycling Test ◽  
Fine Pitch ◽  
Alloy Solder ◽  
Injection Molded

Abstract IBM has developed and has been enhancing the injection molded solder (IMS) technology as an advanced solder bumping technology with flexible solder alloy composition applicable even to fine pitch and small diameter systems. IMS is a simple bumping technology that can form solder bumps by injection of molten solder into via holes patterned in a photoresist layer. IMS is applicable to formation of solder caps for Cu pillar bumping which is a technology widely used for fine pitch applications. One of the advantages of IMS is the capability of using ternary, quaternary, or more compositions solder alloys for bumping, which is not achievable by current plating technology. In this study, the feasibility of IMS bumping and flip chip joining with quaternary solder alloys is demonstrated through assembling of 2.5D package test vehicles using low melting temperature (135°C) SnBi based quaternary alloy solder and associated reliability test. The test vehicles passed the 2250 cycles criteria of thermal cycling test and the observation of microstructures showed that there is no significant crack at the solder joints after flip chip joining or after the 2250 cycles of thermal cycling test. In addition, the tensile test on SnBi based quaternary alloy solder, Sn-58wt%Bi-2.0wt%In with small amount of Pd (less than 1wt%) was conducted using fine diameter specimens. From the SS curve obtained from the test, Young's modulus of the solder was determined as 7.3 GPa and 0.2% proof stress was obtained as 73 MPa both at 25°C. The creep property of the solder was evaluated and the constants for Norton's creep law for the solder were determined at 25, 80 and 110°C. The microstructure observation and Energy Dispersive X-ray (EDX) analysis of the flip chip joints revealed the formation of a thick bismuth (Bi) layer between CuSn intermetallic compound (IMC) layers within a joint. The mechanical simulation of the 2.5D test vehicles showed that the thermomechanical stress of a flip chip joint with Bi/CuSn IMCs at thermal cycling condition is comparable to those of CuSn IMC or Sn-3.0Ag-0.5Cu (SAC305) solder joints consistent with the thermal cycling test result. The advantage of using low temperature quaternary solder materials in flip chip packages is confirmed by mechanical simulation of 2D packages at reflow condition which showed lower stress on low-k dielectric layers for the packages with quaternary solder joints than for the packages with SAC305 solder joints.

Reliability of Fine Pitch Sn–3.8Ag–0.7Cu Flip Chip Solder Joints With Different Connection Pads on PCB

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Dezhi Li ◽  
Changqing Liu ◽  
Paul P. Conway
Keyword(s):  
Flip Chip ◽  
Printed Circuit Boards ◽  
Solder Joints ◽  
Bulk Solder ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Fine Pitch ◽  
Solder Volume ◽  
Failure Location ◽  
Solder Interface

The reliability of fine pitch Sn–3.8Ag–0.7Cu flip chip solder joints with three different pads, i.e., bare pads, pads with solder masks, and pads with microvia, on printed circuit boards (PCBs) was studied through thermal cycling. After assembly, (Au,Ni)Sn4 intermetallics (IMCs) formed both in the bulk solder and at the interfaces due to the immersion-Au finish on the PCB side. The (Au,Ni)Sn4 IMCs formed in the solder joints on the pads with microvia were more abundant than those formed in the solder joints on the pads without microvia. The results showed that the solder joints on the pads with a microvia had poor reliability due to the insufficient solder volume and the formation of large amounts of (Au,Ni)Sn4 IMCs. The main crack initiation position was the corner of solder joint at the chip side. For the pads with microvia, the main location of failure was at the (Au,Ni)Sn4/solder interface on the chip side, and for the solder joints on bare pads and pads with solder mask, the possible failure location was in the bulk solder.

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