Embedding materials

Electrical Properties. Electrical properties are important for the corrosion protection of chip-on-board (COB) encapsulated devices. Accelerated temperature, humidity, and bias (THB) are usually used to test the embedding materials. Conventional accelerating testing is done at 85°C, 85% relative humidity, and d-c bias voltage. Triple-track test devices with tantalum nitride (Ta2N), titanium—palladium—gold (Ti—Pd—Au) metallizations with 76... 

To achieve low stress embedding material, low modulus material such as siUcones (elastomers or gels) and polyurethanes are usually used. Soft-domain elastomeric particles are usually incorporated into the hard (high modulus) materials such as epoxies and polyimides to reduce the stress of embedding materials. With the addition of the perfect particle size, distribution, and loading of soft domain particles, low stress epoxy mol ding compounds have been developed as excellent embedding materials for electronic appHcations. 

Rheological Properties. Materials must have suitable flow properties in order to be used in production. Both Newtonian and non-Newtonian fluids and their viscoelasticity properties play a critical role in the performance of the embedding materials. 

In order to optimize each embedding material property, complete cure of the material is essential. Various analytical methods are used to determine the complete cure of each material. Differential scanning calorimetry, Fourier transform-iafrared (ftir), and microdielectrometry provide quantitative curing processiag of each material. Their methods are described below. 

Rheological properties, See also Rheology of dry foams, 12 16 of embedding materials, 10 10 of encapsulants, 10 12-13 of linear low density polyethylene,... 

Thermoplastic resins, development of, 10 172, 19 536, 537-539 packaging requirements for, 19 538 Thermoplastics, 15 407, 2 620. See also Engineering thermoplastics amorphous, 19 537 as embedding materials, 10 8 epoxy-based, 10 365 fabrication of, 26 765-766 in hazardous waste management, 25 824... 

In addition, from ultrathin slices of the embedded material HRTEM images were obtained in different crystallographic orientations ([001] (see Fig.5), [101], [110], [-111], [102], [120], [201], [122], [203], [301], [1-19], [-124]). Using the structure model of Rius et al. the comparison of kinematically electron diffraction patterns have been compared with experimental data (Cerius 4.2 [8]) as shown in Fig. 6. The basic course of... 

We have also used this method on acetone-fixed paraffin-embedded material with equal success. Slices of fresh liver are fixed in ice-cold acetone for at least 4 h. Material can then be transferred to a -20°C freezer prior to routine embedding and sectioning. In this case, uncoated glass slides were used. 

We have also used this method successfully on formalin-fixed paraffin-embedded material. For the technique to work under these conditions, the sections are microwaved in O.OlMcitric acid, pH 6.0, for approx 14 min on full power (700 W) The exact time of incubation required varies depending on the tissue and must be determined by experimentation. 

For sufficient contrast, most specimens will require lead staining after the uranium acetate stain. Although all conventional lead stains can be used, we found staining with Millonig s lead hydroxide for 2 min under N2 best for Lowicryl and LR Gold embedded material. 

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