Reliability of fine pitch Sn-3.8Ag-0.7Cu flip chip solder joints with different connection pads

2006 ◽  
Author(s):  
Dezhi Li ◽  
Changqing Liu ◽  
P.P. Conway
Keyword(s):  
Flip Chip ◽  
Solder Joints ◽  
Fine Pitch

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.

Fracture Behaviors of Simulated Sn-Ag-Cu Solder Microbumps: Effects of Joint Scale and Aging

2013 ◽  
Author(s):  
Z. Huang ◽  
I. Dutta ◽  
G. S. Subbarayan
Keyword(s):  
Fracture Mechanics ◽  
Mixed Mode ◽  
Flip Chip ◽  
Solder Joints ◽  
Small Scale ◽  
Joint Thickness ◽  
Fine Pitch ◽  
Fracture Behaviors ◽  
Cu Substrates ◽  
Very High

Solder microbumps are widely applied in 3D packages using fine-pitch Cu-pillar or Through Silicon Via (TSV) technologies. Due to the small scale of these joints, the volumetric proportion of intermetallic compounds (IMCs) formed in these joints is typically very high. This renders microbump-joints much more brittle compared to traditional solder joints (flip-chip or BGA). In particular, the reliability of microbumps during a drop, which corresponds to a mixed-mode high strain rate fracture test, is of substantial concern because of the brittleness of these joints. This study reports on the fracture mechanics and mechanisms of simulated microbumps, which have similar thicknesses and IMC contents as actual microbumps, but are laterally scaled up to constitute valid fracture mechanics samples. Compact mixed mode (CMM) specimens with adhesive solder joints (Sn-3.0%Ag-0.5%Cu) between massive Cu substrates were utilized to measure the fracture properties. The fracture behavior was characterized as a function of joint thickness and proportion of IMC, the latter being controlled by adjusting the dwell time and aging time. It was found that the fracture toughness GC decreased monotonically with joint thickness (hJoint) due to increased triaxial constraint imposed by the substrates. With aging, the proportion of IMC thickness relative to the joint thickness (2hIMC/hJoint) increased, as did hJoint. This resulted in lower GC values. The associated mechanisms of fracture that led to these effects are discussed.

scholarly journals Demonstration of fine pitch FCOB (Flip Chip on Board) assembly based on solder bumps at Fermilab

2009 ◽  
Vol 4 (11) ◽  
pp. T11001-T11001
Author(s):  
E Skup ◽  
M Trimpl ◽  
R Yarema ◽  
J C Yun
Keyword(s):  
Flip Chip ◽  
Fine Pitch ◽  
Solder Bumps

Rapid diagnosis of electromigration induced failure time of Pb-free flip chip solder joints by high resolution synchrotron radiation laminography

2011 ◽  
Vol 99 (8) ◽  
pp. 082114 ◽  
Author(s):  
Tian Tian ◽  
Feng Xu ◽  
Jung Kyu Han ◽  
Daechul Choi ◽  
Yin Cheng ◽  
...  
Keyword(s):  
High Resolution ◽  
Synchrotron Radiation ◽  
Flip Chip ◽  
Solder Joints ◽  
Failure Time ◽  
Rapid Diagnosis

Crack Propagation Experiments on Flip Chip Solder Joints

1998 ◽  
Vol 515 ◽  
Author(s):  
S. Wiese ◽  
F. Feustel ◽  
S. Rzepka ◽  
E. Meusel
Keyword(s):  
Crack Propagation ◽  
Flip Chip ◽  
Solder Joints ◽  
Shear Loading ◽  
Displacement Curve ◽  
In Situ Experiments ◽  
Propagation Experiment ◽  
Crack Propagation Experiment ◽  
Number Of Cycles ◽  
Force Displacement

ABSTRACTThe paper presents crack propagation experiments on real flip chip specimens applied to reversible shear loading. Two specially designed micro testers will be introduced. The first tester provides very precise measurements of the force displacement hysteresis. The achieved resolutions have been I mN for force and 20 nm for displacement. The second micro tester works similar to the first one, but is designed for in-situ experiments inside the SEM. Since it needs to be very small in size it reaches only resolutions of 10 mN and 100nm, which is sufficient to achieve equivalence to the first tester. A cyclic triangular strain wave is used as load profile for the crack propagation experiment. The experiment was done with both machines applying equivalent specimens and load. The force displacement curve was recorded using the first micro mechanical tester. From those hysteresis, the force amplitude has been determined for every cycle. All force amplitudes are plotted versus the number of cycles in order to quantify the crack length. With the second tester, images were taken at every 10th … 100th cycle in order to locate the crack propagation. Finally both results have been linked together for a combined quatitive and spatial description of the crack propagation in flip chip solder joints.

Effect of entropy production on microstructure change in eutectic SnPb flip chip solder joints by thermomigration

2006 ◽  
Vol 89 (22) ◽  
pp. 221906 ◽  
Author(s):  
Fan-Yi Ouyang ◽  
K. N. Tu ◽  
Yi-Shao Lai ◽  
Andriy M. Gusak
Keyword(s):  
Entropy Production ◽  
Flip Chip ◽  
Solder Joints ◽  
Microstructure Change ◽  
Eutectic Snpb

A Study of the Aperture Filling Process in Solder Paste Stencil Printing

1999 ◽  
Author(s):  
Jianbiao Pan ◽  
Gregory L. Tonkay
Keyword(s):  
Flip Chip ◽  
Deposition Process ◽  
Area Ratio ◽  
Solder Paste ◽  
Stencil Printing ◽  
Printing Process ◽  
Surface Mount ◽  
Fine Pitch ◽  
Main Indicator ◽  
Advanced Packaging

Abstract Stencil printing has been the dominant method of solder deposition in surface mount assembly. With the development of advanced packaging technologies such as ball grid array (BGA) and flip chip on board (FCOB), stencil printing will continue to play an important role. However, the stencil printing process is not completely understood because 52–71 percent of fine and ultra-fine pitch surface mount assembly defects are printing process related (Clouthier, 1999). This paper proposes an analytical model of the solder paste deposition process during stencil printing. The model derives the relationship between the transfer ratio and the area ratio. The area ratio is recommended as a main indicator for determining the maximum stencil thickness. This model explains two experimental phenomena. One is that increasing stencil thickness does not necessarily lead to thicker deposits. The other is that perpendicular apertures print thicker than parallel apertures.

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