Multiphysics Modeling of Underfill Flow and Cure during Thermocompression Bonding

2015 ◽  
Vol 2015 (1) ◽  
pp. 000526-000529
Author(s):  
Mark Oliver ◽  
Nagi Elabbasi
Keyword(s):  
Dynamic Viscosity ◽  
Temperature Profiles ◽  
Process Variables ◽  
Degree Of Cure ◽  
Multiphysics Modeling ◽  
Conductive Film ◽  
Underfill Flow ◽  
Thermocompression Bonding

We present a model of fillet formation and cure during thermocompression bonding with a non-conductive film. Process variables in the model include the position and temperature profiles applied to the silicon die and substrate by the bonding tool. The chemorheology of the underfill is accounted for in order to track the degree of cure of the material and its impact on dynamic viscosity. Simulation predictions of how the underfill chemorheology impacts the fillet shape and level of cure advance during the processes are presented.

An investigation of the effects of autobrazer parameter variations on the quality of return bend joints

1997 ◽  
Vol 211 (6) ◽  
pp. 443-450 ◽  
Author(s):  
E I Agba ◽  
E W Jones ◽  
A S Penaherrera ◽  
B Thrift
Keyword(s):  
Temperature Profiles ◽  
Process Variables ◽  
Heating Rates ◽  
High Quality ◽  
Parameter Variations ◽  
Brazed Joints ◽  
Temperature Monitor ◽  
Low Probability ◽  
And Control

A temperature monitor that can record brazing temperatures inside an autobrazer for process control and qualification was developed. The monitor was made of a heat exchanger coil instrumented with multiple thermocouples at statistically selected return bend joints that had a high or low probability of leaking. The brazing temperatures recorded at the selected return bends were compared with control temperature profiles for high-quality brazed joints. The results clearly accentuated the disparities in the heating rates, the cooling rates and the peak bonding temperatures between the non-leaking joints and the leaking joints. The autobrazer process parameters were then correlated with a number of leaks and leak locations to determine how to configure the autobrazer and control the process variables to ensure similar brazing conditions at all joints. By so doing, the repeatability of the brazing process and the production of high-quality joints was guaranteed.

Non-Conductive Film (NCF) with No Voiding and High Reliability

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 1-28 ◽  
Author(s):  
Edgardo Anzures ◽  
Anupam Choubey ◽  
Avin Dhoble ◽  
David Fleming ◽  
Robert Barr ◽  
...  
Keyword(s):  
High Reliability ◽  
New Technology ◽  
High Volume ◽  
Temperature Cycling ◽  
Significant Activity ◽  
Wafer Level ◽  
Dimensional Changes ◽  
Conductive Film ◽  
Thermocompression Bonding ◽  
Multiple Devices

There has been significant activity in recent years to develop Non-Conductive Films (NCF), which are also known as Pre-Applied Underfills (PAUF) and Wafer Level Underfills (WLUF), for use in the High Volume Manufacturing (HVM) of 2.5D and 3D packages. They are essentially underfills in laminate film form. Like other underfills, they ensure the integrity of the electrical interconnects in a package by mitigating stress, acting as an adhesive to bind the package together, and encapsulating to protect against moisture and other unwanted materials that can compromise electrical connectivity. NCF's are seen as an alternative to the more traditional capillary underfills, especially in devices with finer pitch, smaller gap, and larger size. Since the NCF can be applied to multiple devices simultaneously, this new technology has an advantage over capillary underfills in HVM. These film-type underfills can be applied to wafers (PAUF, WLUF, NCF) or substrates (PAUF, NCF). Two key attributes of any underfill are no voiding and high reliability. No voiding is an essential requirement for high reliability. Voiding in NCF materials can result from the lamination and thermocompression bonding (TCB) processes. Voiding under the die can manifest from a variety of causes, including some of the following: (1) volatilization of materials in the coating, (2) dimensional changes within the coating during processing, (3) poor fundamental conformation to surface topography during film lamination and (4) ineffective air release during TCB due to un-optimized material flow. Unwanted issues such as reduced adhesion, solder shorting, increased moisture uptake and reduced stress mitigation can result from the presence of voids in the NCF. Pressure cure after joining is one method for eliminating voids in NCF materials. An earlier version of the NCF discussed in this study required pressure to eliminate voids after TCB. Pressure curing, however, adds process steps and is not accepted by all manufacturers. An improved NCF formulation and bonding process has resulted in a void-free NCF that does not require pressure cure for void elimination. This improved version not only addresses voiding after bonding, but also it has been proven to be very reliable in the presence of extreme temperatures, high humidity and temperature cycling. No one test is sufficient to adequately determine the long term reliability of NCF materials so a battery of tests was run to conduct a comprehensive assessment. The reliability evaluation results demonstrate that this newly developed NCF exhibits not only no voiding after TCB without the need for pressure cure, but also high reliability to various forms of temperature and humidity stress testing.

Effects of the Thermocompression Bonding on the Microstructure and Contact Resistance for the Ultrafine Pitch Chip-on-Glass Packaging With Nonconductive Film

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Jianhua Zhang ◽  
Jinsong Zhang ◽  
Lianqiao Yang
Keyword(s):  
Contact Resistance ◽  
Bonding Temperature ◽  
Anisotropic Conductive Film ◽  
Bonding Parameters ◽  
Conductive Film ◽  
Geometric Size ◽  
Ε Phase ◽  
Thermocompression Bonding ◽  
Temperature And Pressure ◽  
Glass Packaging

Nonconductive film (NCF) is a challenging potential material to substitute the application of anisotropic conductive film in the ultrafine pitch chip-on-glass (COG) packaging. The NCF interconnection requires a high bonding temperature and pressure to form joints, and this causes new reliability concerns. This study investigated effects of the thermocompression bonding parameters on the microstructure and geometric size in the joints to a COG module packaged with NCF. The results revealed that the high temperature and pressure compressed the joints to become wider and shorter. A dual layer of intermetallic compounds consisting of AuSn2 (ε phase) and AuSn4 (η phase) was found in each joint. They were the two kinds of interphases with different melting points (AuSn2:309°C and AuSn4:257°C) during the interfacial reaction between Au and Sn. At the low temperature (below the melting point), the high pressure induced the residual inner stress to generate the cracks in the joints, and this also increased the contact resistance of the joints. The contact resistance increased with the pressure elevating at the same temperature and with the temperature degrading at the same pressure. In the COG packaging with NCF, a proper elevating of the bonding temperature could produce a stable direct connection with the low contact resistance.

Key process variables in group treatment for substance use

2013 ◽  
Author(s):  
P. Crits-Christoph ◽  
J. E. Johnson ◽  
M. B. Connolly Gibbons ◽  
R. Gallop
Keyword(s):  
Substance Use ◽  
Group Treatment ◽  
Process Variables
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