scholarly journals A Comparison of Adhesion Behavior of Urea-Formaldehyde Resins with Melamine-Urea-Formaldehyde Resins in Bonding Wood

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1037
Author(s):  
Seongsu Park ◽  
Bora Jeong ◽  
Byung-Dae Park
Keyword(s):  
Penetration Depth ◽  
Molar Mass ◽  
Urea Formaldehyde ◽  
Gelation Time ◽  
High Viscosity ◽  
Bond Line ◽  
Line Thickness ◽  
Bond Line Thickness ◽  
Adhesion Behavior ◽  
Resin Penetration

This paper reports a comparison of adhesion behavior of urea-formaldehyde (UF) with those of melamine-urea-formaldehyde (MU) resins in bonding wood by analyzing the results published in literatures. For this purpose, the adhesion behavior of UF resins prepared by blending low-viscosity resin (LVR) with high-viscosity resin (HVR) at five different blending and two formaldehyde/urea (F/U) molar ratios (1.0 and 1.2) was compared with those of two MUF resins synthesized by either simultaneous reaction (MUF-A resins) or multi-step reaction (MUF-B resins) with three melamine contents (5, 10, and 20 wt%). As the blending (LVR:HVR) ratio increased from 100:0 to 0:100, the viscosity and molar mass (Mw and Mn) of the blended UF resins increased while the gelation time decreased. The interphase features such as maximum storage modulus (E′max), resin penetration depth, and bond-line thickness of the UF resins increased to a maximum and then decreased as the blending ratio increased. In addition, both MUF-A and MUF-B resins also showed an increase in the Mw and Mn as the melamine content increased from 5% to 20%. However, the E′max, resin penetration depth, and bond-line thickness of the MUF resins decreased as the molar mass or melamine content increased. These results indicated that the adhesion of UF resins heavily depends on the interphase features while that of the MUF resins highly depends on the cohesion of the resins.

scholarly journals Effect of Bond-Line Thickness on Fatigue Crack Growth of Structural Acrylic Adhesive Joints

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1723
Author(s):  
Yu Sekiguchi ◽  
Chiaki Sato
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Behavior ◽  
Adhesive Bond ◽  
Bond Line ◽  
Loading Conditions ◽  
Fatigue Crack Growth Resistance ◽  
Line Thickness ◽  
Bond Line Thickness

With an increasing demand for adhesives, the durability of joints has become highly important. The fatigue resistance of adhesives has been investigated mainly for epoxies, but in recent years many other resins have been adopted for structural adhesives. Therefore, understanding the fatigue characteristics of these resins is also important. In this study, the cyclic fatigue behavior of a two-part acrylic-based adhesive used for structural bonding was investigated using a fracture-mechanics approach. Fatigue tests for mode I loading were conducted under displacement control using double cantilever beam specimens with varying bond-line thicknesses. When the fatigue crack growth rate per cycle, da/dN, reached 10−5 mm/cycle, the fatigue toughness reduced to 1/10 of the critical fracture energy. In addition, significant changes in the characteristics of fatigue crack growth were observed varying the bond-line thickness and loading conditions. However, the predominance of the adhesive thickness on the fatigue crack growth resistance was confirmed regardless of the initial loading conditions. The thicker the adhesive bond line, the greater the fatigue toughness.

Die Attach Process Analysis of Enhanced Stand-off Stopper on Tapeless Leadframe

2020 ◽  
pp. 22-26
Author(s):  
E. Graycochea Jr. ◽  
F. Gomez ◽  
R. Rodriguez ◽  
B. Bacquian
Keyword(s):  
Process Analysis ◽  
Semiconductor Industry ◽  
Bond Line ◽  
Line Thickness ◽  
Design Structure ◽  
Die Attach ◽  
Bond Line Thickness ◽  
Improved Design

Improvement on the process and design is often a reliable way to resolve a problem especially in semiconductor industry. This paper presents a leadframe or semiconductor carrier merged with a stand-off design structure that will maintain a consistent bond line thickness (BLT) criteria for quad-flat no-leads (QFN) packages. Through package and process conceptualization, the stand-off design located on the leadframe underneath the silicon die corners would result to a steady and consistent BLT during die attach process. With the improved design, die tilt occurrence in die attach process would be mitigated.

Bond Line Thickness of Thermal Interface Materials With Carbon Nanotubes

2005 ◽  
Author(s):  
Senthil A. G. Singaravelu ◽  
Xuejiao Hu ◽  
Kenneth E. Goodson
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Volume Fraction ◽  
Bond Line ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Line Thickness ◽  
Bond Line Thickness ◽  
The Impact ◽  
Interface Materials

Increasing power dissipation in today’s microprocessors demands thermal interface materials (TIMs) with lower thermal resistances. The TIM thermal resistance depends on the TIM thermal conductivity and the bond line thickness (BLT). Carbon Nanotubes (CNTs) have been proposed to improve the TIM thermal conductivity. However, the rheological properties of TIMs with CNT inclusions are not well understood. In this paper, the transient behavior of the BLT of the TIMs with CNT inclusions has been measured under controlled attachment pressures. The experimental results show that the impact of CNT inclusions on the BLT at low volume fractions (up to 2 vol%) is small; however, higher volume fraction of CNT inclusions (5 vol%) can cause huge increase in TIM thickness. Although thermal conductivities are higher for higher CNT fractions, a minimum TIM resistance exists at some optimum CNT fraction for a given attachment pressure.

scholarly journals Influence of adhesive bond line thickness on joint strength

2009 ◽  
Vol 29 (7) ◽  
pp. 724-736 ◽  
Author(s):  
P. Davies ◽  
L. Sohier ◽  
J.-Y. Cognard ◽  
A. Bourmaud ◽  
D. Choqueuse ◽  
...  
Keyword(s):  
Joint Strength ◽  
Adhesive Bond ◽  
Bond Line ◽  
Line Thickness ◽  
Bond Line Thickness

Effect of resin-rich bond line thickness and fibre migration on the toughness of unidirectional Carbon/PEEK joints

2018 ◽  
Vol 109 ◽  
pp. 197-206 ◽  
Author(s):  
Francisco Sacchetti ◽  
Wouter J.B. Grouve ◽  
Laurent L. Warnet ◽  
Irene Fernandez Villegas
Keyword(s):  
Bond Line ◽  
Line Thickness ◽  
Bond Line Thickness
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