Thermal analysis of flip chip plastic ball grid array assembly

2004 ◽  
Vol 33 (6) ◽  
pp. 371-382
Author(s):  
Ay Su ◽  
Yi-Wei Liu
Keyword(s):  
Thermal Analysis ◽  
Flip Chip ◽  
Ball Grid Array ◽  
Plastic Ball ◽  
Plastic Ball Grid Array

Strain Measurements in a Thermally-Cycled Flip-Chip PBGA Solderball

1999 ◽  
Vol 563 ◽  
Author(s):  
E. S. Drexler
Keyword(s):  
Flip Chip ◽  
Ball Grid Array ◽  
Organic Substrates ◽  
Strain Measurements ◽  
Silicon Chips ◽  
Flip Chips ◽  
Plastic Ball ◽  
Plastic Ball Grid Array ◽  
Ball Grid Array Package ◽  
Solder Fatigue

AbstractThe mismatch between the coefficients of thermal expansion of silicon chips and their organic substrates has been mitigated through the practice of using underfill in flip-chip packages. Yet solder fatigue and package failures still occur. This is particularly true for flip-chips on organic substrates that are thermally cycled between low (−55 °C) and high temperatures (125 °C). In this study, I used electron-beam moir6 to measure displacements and calculate strains in a solderball contained in a flip-chip plastic-ball grid array package. A crossed-line grating with a pitch of 450 nm was used to allow detailed measurements of the local displacements from a cross section of a flip-chip package. Elastic displacements were observed and measured, and the v-field displacements, out of the plane of the chip, were more significant than the shear or u-field, in the plane of the chip, displacements. Larger v-field displacements were measured near the center of the silicon chip than at the edge of the chip.

Effect of Lid Materials on the Solder Ball Reliability of Thermally Enhanced Flip-Chip Plastic Ball Grid Array Packages

2006 ◽  
Vol 306-308 ◽  
pp. 1043-1048
Author(s):  
Yi-Ming Jen ◽  
Hsi Hsin Chien ◽  
Tsung-Shu Lin ◽  
Shih Hsiang Huang
Keyword(s):  
Fatigue Life ◽  
Thermal Fatigue ◽  
Solder Ball ◽  
Flip Chip ◽  
Ball Grid Array ◽  
Stress Strain ◽  
Thermal Fatigue Life ◽  
Plastic Ball ◽  
Plastic Ball Grid Array ◽  
Solder Balls

This research studied the thermal fatigue life for eutectic solder balls of thermally enhanced flip-chip plastic ball grid array (FC-PBGA) packages with different lid materials under thermal cycling tests. Three FC-PBGA packages with different lid materials, i.e., Al, AlSiC, and Cu, were utilized to examine the lid material effect on solder ball reliability. The cyclic stress/strain behavior for the packages was estimated by using the nonlinear finite element method. The eutectic solder was assumed to be elastic-plastic-creep. The stable stress/strain results obtained from FEM analysis were utilized to predict the thermal fatigue life of solder balls by using the Coffin-Manson prediction model. Simulation results showed that the fatigue life of the FC-PBGA package with a Cu lid was much shorter than FC-PBGA packages with other lid materials. The relatively shorter fatigue life for the FC-PBGA package with a Cu lid was due to the complex constrained behavior caused by the thermal mismatch between the lid, substrate and the printed circuit board. The difference was insignificant in the fatigue lives between the package with an Al lid and the conventional package.

An Evaluation of Thermal Enhancements to Flip-Chip-Plastic Ball Grid Array (FC-PBGA) Packages

2003 ◽  
Author(s):  
K. Ramakrishna ◽  
T.-Y. Tom Lee
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Flip Chip ◽  
Ball Grid Array ◽  
Heat Spreader ◽  
Thermal Enhancement ◽  
Plastic Ball ◽  
Plastic Ball Grid Array ◽  
Underfill Material

Flip-chip plastic ball grid array (FC-PBGA) packages are fast becoming the industry norm, in particular in the performance and cost driven consumer electronics sector. Since high thermal conductivity (k∼15–20 W/(m K)) ceramic substrate is replaced by a low conductivity (k∼0.2–0.5 W/(m K)) organic substrate in the FC-PBGA packages, enhancement of thermal performance of these packages to meet ever increasing demands is crucial for their wide spread use. In this study, enhancements to thermal performance of FC-PBGA packages due to material and design changes and external means such as heat spreaders and overmolding of the packages have been evaluated by solving a conjugate heat transfer models using the methods of computational fluid dynamic. The thermal enhancements evaluated in this study include the effect of thermal conductivity of the chip to package interconnect due to change in underfill material and the C4 bump pitch, effect of package to printed wiring board (PWB) interconnection through the use of thermal balls, effect of a heat spreader on the backside of the die, and overmolding the die without and with a heat spreader. Thermal performance of the FC-PBGA packages have been studied using junction to ambient thermal resistance, Θja, junction-to-board thermal resistance Ψjb, and junction to case thermal resistance ΨjT under natural and forced convection for freestream velocities up to 2 m/s and the for following ranges of parameters: Substrate size: 25 to 35 mm, die size: 6.19×7.81 mm (48 mm2 area) and 9.13×12.95 mm (118 mm2 area), C4 pitch: 250 mm, 150 mm and below, underfill material thermal conductivity: 0.6 to 3.0 W/(m K), no thermal balls between the package and the PWB to 9×9 array of thermal balls on 1.27 mm square pitch, and with copper heat spreader on the back of the bare and overmolded die. Based on previous experience, predictions in this study are expected to be within ±10% of measured data. The following conclusions are drawn from this study: 1. It is concluded that the thermal conductivity of the underfill materials in the range 0.6 to 10 W/(m K) is negligible. 2. It is also concluded that the bump pitch can decrease thermal resistances by 12 to 15 %. The change may be smaller with large die area. 3. Thermal balls (C5) connected to the PTHs in the PWB can decrease thermal resistance by about 10% to 15% as the number of thermal balls & PTHs increase zero to 9×9 on 1.27 mm pitch. The effect die size on this thermal enhancement is more noticeable on Ψjb. 4. Heat spreader on the back of the die decreases Θja by a small amount (6–7%) in natural convection and a large amount, about 25% in forced convection. 5. Overmolded die with heat spreader on the top of the overmold provides better thermal enhancement than heat spreader alone up to about 1 m/s. Beyond 1 m/s, heat spreader (without overmold) performs slightly better.

Comparative Study of Phenolic-Based and Amine-Based Underfill Materials in Flip Chip Plastic Ball Grid Array Package

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Z. Kornain ◽  
A. Jalar ◽  
R. Rasid ◽  
S. Abdullah
Keyword(s):  
Adhesion Strength ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Ball Grid Array ◽  
Bending Test ◽  
Temperature Cycle ◽  
Storage Test ◽  
Plastic Ball ◽  
Plastic Ball Grid Array ◽  
Epoxy Systems

Phenolic and amine epoxy systems are widely used as hardeners in underfill materials for flip chip packaging. A comparison was made between these two systems in order to evaluate the reliability performance of a flip chip plastic ball grid array (FC-PBGA). The coefficient of thermal expansion, glass transition temperature (Tg), Young’s modulus (E), and fracture toughness were revealed by using a thermal mechanical analyzer, a dynamic mechanical analyzer, and a single-edge notch three-point bending test, while moisture absorption study was performed using an 85°C/85% relative humidity chamber. The adhesion strength with different conditions of temperature and humidity was performed using a die shear test. The series of standard reliability tests such as accelerated temperature cycle test, pressure cooker test, thermal humidity storage test, and high temperature storage test were executed upon the FC-PBGA, which was filled by phenolic and amine epoxy systems of underfill materials. It was found that the adhesion strength of phenolic-based underfills is better than that of amine-based underfills in almost all test conditions. Phenolic-based underfills also demonstrated better reliability compared with amine-based underfills.

Sign in / Sign up

Export Citation Format

Share Document