Thermal Degradation and Mass Transport of Underfill Material

2007 ◽  
Author(s):  
Wen-Hao Lee ◽  
D. S. Liang ◽  
W. P. Wang ◽  
C. S. Hsiao
Keyword(s):  
Thermal Degradation ◽  
Mass Transport ◽  
Adhesion Strength ◽  
Moisture Absorption ◽  
Plastic Material ◽  
Water Molecules ◽  
Packaging Materials ◽  
Weight Loss Curve ◽  
Solder Reflow ◽  
Underfill Material

In order to enhance the reliability of flip chip packages, the initiation and propagation of various interfacial failures and robust interfacial bonds between the underfill and the other components are highly desired. The water molecules inside the plastic material were chemically bonded with polymers by hydrogen bonds in the microholes formed by the polymer molecule chains. The bonding of water molecules and polymers reduced the adhesion strength at the interface between epoxy material and die. In this study, the interfacial bond strengths of commercial underfills with silicon nitride passivation are measured using bottom shear test. The thermal degradation of epoxy-based underfill material has been studied by thermogravimetric analysis (TGA). The results show that adhesion strength is correlated with TGA weight loss curve. Besides, epoxy is sensitive to moisture at high temperature storage. Moisture diffusion characterization at high temperatures in polymeric packaging materials is important since moisture absorption of polymeric packaging materials plays a determining role in “popcorn cracking” of IC packages during the solder reflow process especially for lead-free solder reflow profile. The moisture absorption was measured by using mass transport and diffusion theory.

Hygrothermal stress analysis of a plastic ball grid array package during solder reflow

2004 ◽  
Vol 218 (9) ◽  
pp. 957-970 ◽  
Author(s):  
K-C Chang ◽  
M-K Yeh ◽  
K-N Chiang
Keyword(s):  
Finite Element ◽  
Moisture Absorption ◽  
Ball Grid Array ◽  
Design Parameters ◽  
Shear Stresses ◽  
Packaging Materials ◽  
Element Analysis ◽  
Plastic Ball ◽  
Plastic Ball Grid Array ◽  
Solder Reflow

This study investigated how the internal temperature and moisture of a plastic ball grid array (PBGA) package affect interfacial hygrothermal stresses (primarily peeling and shear stresses) during solder reflow. Two-dimensional finite element analysis was applied to evaluate temperature distribution, moisture diffusion and hygrothermal stresses inside the PBGA package. A series of popcorn experiments on PBGA packages was carried out to verify the accuracy of the finite element model. The design parameters of the PBGA package were varied to assess their effect on hygrothermal stresses at the interfaces. Moisture absorption and desorption experiments on the PBGA packaging materials were conducted in a hygrothermal chamber and an oven, to obtain moisture diffusivity data and saturated moisture contents of PBGA packaging materials. Results in this study can be applied to optimize the design parameters of the PBGA package and thus reduce interfacial hygrothermal stresses during solder reflow.

Thermoplastic Optical Polymers with Lead-Free Solder Reflow Resistance for HB-LED Packaging and Assembly

2010 ◽  
Vol 2010 (1) ◽  
pp. 000156-000163
Author(s):  
Weijun Zhou ◽  
Quan Yuan ◽  
Chris Li ◽  
Stephen F. Hahn ◽  
Kurt A. Koppi ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Dimensional Stability ◽  
Moisture Absorption ◽  
Lead Free ◽  
Lead Free Solder ◽  
Optical Polymers ◽  
Reflow Process ◽  
Short Period ◽  
Solder Reflow ◽  
Free Solder

A new class of thermoplastic optical polymers made by substantially fully hydrogenating block copolymers of styrene and butadiene, known as cyclic block copolymers (CBCs), were recently discovered to exhibit lead-free solder reflow resistance with peak reflow temperature up to 260°C. This kind of behavior is uncommon for traditional thermoplastic polymers. The block copolymer design and the resulting nanostructured morphology lead to strong elastic and soft solid material characteristics for CBC, which may explain why CBCs can maintain good dimensional stability at high temperatures (i.e., above its glass transition temperature, Tg) for a short period of time such as in a solder reflow process. This hypothesis was examined by computational fluid dynamics modeling on a molded CBC lens of LUXEON K2 LED package configuration. When the CBC lens is subjected to a simulated solder reflow process, the change in physical dimension due to thermal expansion and gravity effects is predicted to be negligible. However, the residual stress in the molded lens may play a profound role on its dimensional stability. There exists a critical stress value below which no observable deformation is predicted for the CBC lens. With excellent optical transparency and good long term optical stability, low moisture absorption, and good injection moldability, CBCs is a promising class of materials for LED packaging that contributes to improved LED manufacturing economics.

Improving Releasability of Mold Materials for IC Encapsulation Using Epoxy Compounds

2012 ◽  
Vol 706-709 ◽  
pp. 2529-2534
Author(s):  
Satoshi Kitaoka ◽  
Naoki Kawashima ◽  
Masato Yoshiya ◽  
Shigeru Miyagawa ◽  
Yoshinori Noguchi ◽  
...  
Keyword(s):  
Surface Energy ◽  
Adhesion Strength ◽  
Integrated Circuit ◽  
Active Sites ◽  
Dissociative Adsorption ◽  
Water Molecules ◽  
Molding Compounds ◽  
Co Doping ◽  
Ceramic Surfaces ◽  
Adsorption Of Water

The effect of dopants such as zirconium and nitrogen on the releasability of Y2O3-based ceramics from molds was investigated for integrated circuit packaging using epoxy molding compounds (EMCs). Co-doping of these elements was carried out by annealing the surfaces of 5mol% ZrO2-Y2O3 samples under a N2 flow at 1100-1300 °C, resulting in concentration of nitrogen near the surfaces of the samples. The adhesion strength was minimized by exposure at about 1200-1250 °C, which was less than half the value for the undoped Y2O3. The co-doping remarkably decreased the polar part of the surface energy and consequently hydrophobicity of the ceramic surfaces increased. The excellent releasability characteristics were likely related to the depression of dissociative adsorption of water molecules, which are considered to act as active sites for the adhesion of EMCs.

The Mechanics and Impact of Hygroscopic Swelling of Polymeric Materials in Electronic Packaging

2002 ◽  
Vol 124 (2) ◽  
pp. 122-126 ◽  
Author(s):  
E. H. Wong ◽  
R. Rajoo ◽  
S. W. Koh ◽  
T. B. Lim
Keyword(s):  
Thermal Stress ◽  
Electronic Packaging ◽  
Flip Chip ◽  
Polymeric Materials ◽  
Packaging Materials ◽  
Excellent Correlation ◽  
Reliable Technique ◽  
Hygroscopic Swelling ◽  
Solder Reflow ◽  
Swelling Characteristics

A reliable technique for characterizing the hygroscopic swelling of materials has been developed and used to characterize a number of packaging materials. Using these data, hygroscopic stress modeling were performed. The hygroscopic stress induced through moisture conditioning was found to be significant compared to the thermal stress during solder reflow. Hygroscopic stress in over-molded wire bond PBGA and molded Flip Chip PBGA was found to be 1.3 times to 1.5 times that of thermal stress. Hygroscopic swelling of the underfill in FCPBGA was found to be the main failure driver during autoclave test. Autoclave performance of FCPBGA package assembled with different underfills and chips were analyzed. Excellent correlation was found between autoclave performance and the hygroscopic swelling characteristics of the underfills.

scholarly journals A Molecular Interpretation of the Dynamics of Diffusive Mass Transport of Water within a Glassy Polyetherimide

2021 ◽  
Vol 22 (6) ◽  
pp. 2908
Author(s):  
Andrea Correa ◽  
Antonio De Nicola ◽  
Giuseppe Scherillo ◽  
Valerio Loianno ◽  
Domenico Mallamace ◽  
...  
Keyword(s):  
Mass Transport ◽  
Chemical Potential ◽  
Fluid Model ◽  
Diffusion Mechanism ◽  
Sorption Kinetics ◽  
Glassy Matrix ◽  
Water Molecules ◽  
Lattice Fluid ◽  
Molecular Interpretation ◽  
Dynamics Simulations

The diffusion process of water molecules within a polyetherimide (PEI) glassy matrix has been analyzed by combining the experimental analysis of water sorption kinetics performed by FTIR spectroscopy with theoretical information gathered from Molecular Dynamics simulations and with the expression of water chemical potential provided by a non-equilibrium lattice fluid model able to describe the thermodynamics of glassy polymers. This approach allowed us to construct a convincing description of the diffusion mechanism of water in PEI providing molecular details of the process related to the effects of the cross- and self-hydrogen bonding established in the system on the dynamics of water mass transport.

scholarly journals Factors affecting betacyanin stability in juice of LD5 Red-fleshed dragon fruit (Hylocereus polyrhizus)

2018 ◽  
Vol 17 (06) ◽  
pp. 72-76
Author(s):  
Ngan N. T. Trinh
Keyword(s):  
Ascorbic Acid ◽  
Fruit Juice ◽  
Light Exposure ◽  
Plastic Material ◽  
Heating Time ◽  
Packaging Materials ◽  
Factors Affecting ◽  
Acid Addition ◽  
Dragon Fruit ◽  
Hylocereus Polyrhizus

In Binh Thuan province (Vietnam), the red-fleshed dragon fruit (Hylocereus polyrhizus), concretely LD5 variety majorly grows and contains a large amount of betacyanin, a natural colourant that potentially applied to many products in the food industry. In this study, the processing factors possibly influencing the betacyanin stability in the red-fleshed dragon fruit juice were in turn investigated. The heating treatment included 2 factors: temperature (65, 75 and 85oC) and heating time (10, 20 and 30 minutes); while the pH values ranged between 3.0 to 7.0 and the ascorbic acid addition varied in concentrations (0.1, 0.2, 0.3, 0.4 and 0.5% w/w). The processed fruit juice was stored in different packaging materials (plastic and glass) with and without light exposure for 5 weeks to monitor the retained betacyanin. The results showed that the betacyanin was remained with the highest proportion (0.84 ± 0.02) at 0.3% ascorbic acid addition, pH 4.0 and heat treatment at 65oC for 10 minutes. In storage without light exposure, both plastic and glass packaging materials kept efficiently betacyanin in fruit juice. However, the glass material represented better efficiency in the betacyanin remaining than the plastic material did.

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