A Comparative Study of the Performance of Compact Model Topologies and Their Implementation in CFD for a Plastic Ball Grid Array Package

2000 ◽  
Vol 123 (3) ◽  
pp. 232-237 ◽  
Author(s):  
Sarang Shidore ◽  
Tien Yu Tom Lee
Keyword(s):  
Natural Convection ◽  
Forced Convection ◽  
Network Model ◽  
Ball Grid Array ◽  
Cold Plate ◽  
Detailed Model ◽  
Plate Test ◽  
Plastic Ball ◽  
Plastic Ball Grid Array ◽  
Compact Models

A detailed model of a die-up 256-pin Plastic Ball Grid Array (PBGA) package was created and validated against experimental data for natural convection and forced convection environments. Next, four compact models were derived; two two-resistor models (one created through a two-point computational cold plate test; the other using the DELPHI optimization approach), a multi-resistor Star network model and a shunt network model. The latter three models were derived using the methodology established by the DELPHI (Development of Libraries of Physical models for an Integrated design environment) project. The four compact models and the detailed model were each placed in natural convection and forced convection (velocities of 1,2, and 4 m/s) environments. Good agreement was obtained for the die-junction temperature rise for both the detailed and the shunt compact models. The star and two-resistor models were seen to be inferior in terms of accuracy. The two-resistor model created using the DELPHI methodology was found to be superior compared to the one created with the computational cold-plate test. The star model showed little gain in performance as compared to the DELPHI two-resistor model.

Prediction of Thermal Performance of Wire-Bonded Plastic Ball Grid Array Package for Underhood Automotive Applications

2003 ◽  
Vol 125 (3) ◽  
pp. 447-455 ◽  
Author(s):  
K. Ramakrishna ◽  
J. R. Trent
Keyword(s):  
Thermal Conductivity ◽  
Natural Convection ◽  
Ambient Temperature ◽  
Thermal Performance ◽  
Ball Grid Array ◽  
Automotive Applications ◽  
Molding Compound ◽  
Wide Range ◽  
Plastic Ball ◽  
Plastic Ball Grid Array

Thermal performance of a three chip, overmolded wire-bonded plastic ball grid array (WB-PBGA) package with four layer substrate attached to a 1.52-mm-thick, four-layer (2s2p), FR4 printed wiring board (PWB) has been evaluated under horizontal natural convection conditions for underhood automotive applications as a function of ambient temperature, package design parameters, and thermophysical properties of the package and PWB materials. A two-tier modeling approach, which accurately accounts for multidimensional heat transfer effects caused by substrate features such as vias and C5 solder joints, has been developed and implemented. In this methodology, the effect of small features is first characterized using a detailed micromodel from which an effective thermal conductivity is computed. The effective thermal conductivity is implemented in the global model thereby excluding the small features in the global model. The actual stackups of the package and PWB have been used in the computations to accurately determine the in-plane heat spreading. Using this methodology for automotive underhood applications, a parametric study of thermal performance of the WB-PBGA package has been carried out. This study shows that: 1. The maximum junction temperature rise above ambient, ΔT, decreases with increase in ambient temperature by 30% as the ambient temperature increases from 23 to 125°C. 2. ΔT decreases by 20% as the emissivity of the molding compound and the PWB surfaces increases from 0 (no radiative loss) to 0.8 under natural convection conditions. 3. The decrease in ΔT is small (∼7%) as the thermal conductivity of the die attach material varies over a wide range. 4. ΔT decreases by 30% as the thermal conductivity of the molding compound is varied over a wide range. 5. ΔT decreases by 45% as the thermal conductivity of the substrate increases (i.e., as the number of vias in the substrate increase) from no vias case to densely populated vias.

Prediction of Thermal Performance of Flip-Chip-Plastic Ball Grid Array (FC-PBGA) Packages: Effect of Die Size

2001 ◽  
Author(s):  
K. Ramakrishna ◽  
T.-Y. Lee
Keyword(s):  
Forced Convection ◽  
Thermal Performance ◽  
Flip Chip ◽  
Ball Grid Array ◽  
Thermal Parameters ◽  
Freestream Velocity ◽  
Asymptotic Values ◽  
Wide Range ◽  
Plastic Ball ◽  
Plastic Ball Grid Array

Abstract Package level thermal performance of flip-chip plastic ball grid array (FC-PBGA) packages has been predicted using experimentally validated mechanistic methodologies. The resulting conjugate heat transfer models have been solved using methods of computational fluid dynamics under natural and forced convection for freestream velocities up to 2 m/s. Overall junction to ambient, Θja, junction-to-board, Ψjb, and junction to case Ψjτ thermal resistances (here after referred to as thermal parameters) have been derived from the results of these computations. Using these models and methodologies, which are previously validated against experimental data, a parametric study of effect of die size on the package thermal parameters has been carried out for die sizes in the range 2 to 20 mm (area of 4–400 mm2) under natural and forced convection with freestream velocities in the range of 0.5 to 2 m/s. The predictions in this study are expected to be ±10% of the measured data. Based on this work the following conclusions have been drawn: 1. The junction to ambient, Θja, and junction to board, Ψjb, thermal resistances decrease with increase in freestream velocity, U, and junction to case thermal resistance, Ψjτ, increases with U. Ψjb shows a weaker dependence on U than Θja does. 2. For a fixed substrate size, package thermal resistances, Θja and Ψjb, decrease as the die size increases from 2 mm (4 mm2) to 20 mm (400 mm2). However, these resistances reach asymptotic values for die sizes above 50 mm2. The change in these resistances is in the range 20% to 35% and the effect of freestream velocity on the percentage changes is small. 3. An extensive database of experimentally validated FC-PBGA package thermal parameters have been generated for a wide range of die sizes.

Backside Application of Acoustic Micro Imaging (AMI) on Plastic Ball Grid Array (PBGA) and Plastic Quad Flat Pack (PQFP) Packages

2004 ◽  
Author(s):  
Luis A. Curiel ◽  
Andrew J. Komrowski ◽  
Daniel J.D. Sullivan
Keyword(s):  
Ball Grid Array ◽  
Acoustic Microscopy ◽  
Electronic Packages ◽  
Nondestructive Technique ◽  
Molding Compound ◽  
Microscopy Technique ◽  
Plastic Ball ◽  
Die Surface ◽  
Plastic Ball Grid Array ◽  
Bond Pads

Abstract Acoustic Micro Imaging (AMI) is an established nondestructive technique for evaluation of electronic packages. Non-destructive evaluation of electronic packages is often a critical first step in the Failure Analysis (FA) process of semiconductor devices [1]. The molding compound to die surface interface of the Plastic Ball Grid Array (PBGA) and Plastic Quad Flat Pack (PQFP) packages is an important interface to acquire for the FA process. Occasionally, with these packages, the standard acoustic microscopy technique fails to identify defects at the molding compound to die surface interface. The hard to identify defects are found at the edge of the die next to the bond pads or under the bonds wires. This paper will present a technique, Backside Acoustic Micro Imaging (BAMI) analysis, which can better resolve the molding compound to die surface interface at the die edge by sending the acoustic signal through the backside of the PBGA and PQFP packages.

The Effect of Ball Pad Metallurgy and Ball Composition on Solder Ball Integrity of Plastic Ball Grid Array Packages

1998 ◽  
Author(s):  
C.H. Zhong ◽  
Sung Yi
Keyword(s):  
Failure Mode ◽  
Barrier Layer ◽  
Shear Force ◽  
Solder Ball ◽  
Ball Grid Array ◽  
Reliability Test ◽  
Shear Forces ◽  
Ball Shear ◽  
Plastic Ball ◽  
Plastic Ball Grid Array

Abstract Ball shear forces of plastic ball grid array (PBGA) packages are found to decrease after reliability test. Packages with different ball pad metallurgy form different intermetallic compounds (IMC) thus ball shear forces and failure modes are different. The characteristic and dynamic process of IMC formed are decided by ball pad metallurgy which includes Ni barrier layer and Au layer thickness. Solder ball composition also affects IMC formation dynamic process. There is basically no difference in ball shear force and failure mode for packages with different under ball pad metallurgy before reliability test. However shear force decreased and failure mode changed after reliability test, especially when packages exposed to high temperature. Major difference in ball shear force and failure mode was found for ball pad metallurgy of Ni barrier layer including Ni-P, pure Ni and Ni-Co. Solder ball composition was found to affect the IMC formation rate.

Plastic Ball Grid Array

2001 ◽  
pp. 577-613
Author(s):  
Mark J. Kuzawinski ◽  
Thomas R. Homa
Keyword(s):  
Ball Grid Array ◽  
Plastic Ball ◽  
Plastic Ball Grid Array
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