Silica filled epoxies

A part, consisting of a carbon fiber composite tube, was initially adhered to the inside of a short titanium coupling by a silica-filled epoxy. The bond failed and a fluorinated mold release was believed to be the cause of the failure and was the purpose for this investigation. A sample of the epoxy (Sample A) and the part (Sample B) were submitted for X-ray photoelectron spectroscopy (XPS) to analyze for the presence of both fluorine and silicon. 

Fig. 25. Effective Young s modulus for silica filled epoxy 46]. Circles are experimental data [45]...

Fig. 26. Comparison of the predicted (solid lines [46]) and measured (points [45]) strain rate dependence of the compressive yield stress of silica filled epoxy at different filler concentrations...

Fig. 28. Dependence of the compressive stress-strain curves on strain rate of silica filled epoxy [46]...

Thermal conductivity and expansion are important properties of adhesives used in electronics. Both properties influence the performance of computer chips. Generally, the chip has a protective cover which is attached by an adhesive. The adhesive bond must be maintained during thermally induced movement in the chip. The chip is bonded to its base with an adhesive which must also take thermal movement and, in addition, transfer heat from the chip. Two epoxy adhesives were used in the study silica filled epoxy (65 and 75 wt% SiO2 epoxy) and epoxy containing 70 wt% Ag. Figure 15.6 shows their thermal conductivities. The behavior of both adhesives is completely different. The silver filled adhesive had a maximum conductivity at about 6()"C whereas the maximum for SiOz filled adhesive was 120"C. The Tg of both adhesives was 50 and 160 C, respectively. Below its Tg, the thermal conductivity of the adhesive increases at the expense of increased segmental motions in the chain molecules. Above the Tg the velocity of photons rapidly decreases with increasing temperature and the thermal conductivity also decreases rapidly. 

The effect of fillers on the gel point of thermosets has not been studied extensively. Ng and Manas-Zloczower (1993) used isothermal dynamic time tests to measure the crossover point for a silica-filled epoxy resin. They noted a decrease in gel time with increasing filler loading. Metzner (1985) also noted that the storage modulus and loss modulus increased by different amounts with filler loading. Therefore, the gel-point tests for highly filled systems must involve knowledge of the effect of filler characteristics at various levels. 

It has been demonstrated that thick layers of fused silica filled epoxy resins with processable viscosities can be UV cured In... 

Silica-filled, epoxy-anhydride undeifill High reliability capillary underfill... 

MG-6 Silica-filled epoxy resins, EP Dexter Corp. 

Glass filled polystyrene Glass filled polyester Graphite fiber filled nylon Glass filled ABS materials Glass filled polycarbonate Silica filled epoxy... 

Fig. 31. Comparison of the profile of the apparent mean viscosity vs, time for the silica filled epoxy molding compound, measured by RPA. (O denotes conventional crushed fused silica and denotes spherical fused silica)...

Because of the thermal contraction mismatch of a silicon chip, metal lead-frame and silica-filled epoxy molding compound integrated circuit (IC) packages bow or warp when cooled to room temperature after manufacture. The magnitude of the bow in an IC package can be determined quantitatively by... 

Silica-filled epoxy molding compounds use an epoxysilane for such a reason. In some cases, special epoxysilanes that have low chloride and low ionic content are used to further minimize negative effects on electrical properties. 

Chem. Descrip. 77% Salt of unsat. polyamine amides and acidic polyesters with 20% 2-butoxyethanol, 2% xylene, 0.5% ethylbenzene Uses Wetting agent, dispersant, vise, reducer for filled, unsat. polyester and epoxy resin systems, esp. those with alumina trihydrate or calcium carbonate fillers and silica-filled epoxy flooring compds. 

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