Silver epoxies

The microarray electrodes used for solid state electrochemistry are a slight variation of the transistor decribed in Sect. 5.2.2 The most appealing feature is the location of all the necessary electrodes on a single microchip, the reference electrode being provided by the application of a droplet of silver epoxy to one of the gold micro electrodes (Fig. 7). 

Figure 23. Processing flow for 3-D electrode array fabrication using silicon micromachining with colloidal filling of the electrode material. The six steps are identified as the following (i) patterned photoresist (PR) on silicon substrate, (ii) PR removal after DRIB micromachining, (iii) insulate silicon mold by oxidation, (iv) colloidal electrode filling material centrifuged into the mold, (v) silver epoxy added to provide mechanical stability and electrical contact, (vi) the electrode flipped over and released from the mold by immersion in a TEAOH solution.

In the study of the electrochemistry of single crystals, e.g. semiconductors, at rotating electrodes, an RDE can be fabricated with a shallow hole and the crystal, after appropriate machining, cemented in place with silver epoxy resin. 

The simplest way to construct these electrodes is to solder or glue with silver epoxy resin a cylindrical specimen of the electrode material to a stainless steel shaft. A mantle of epoxy resin or plastic is then made around the disc to the shape required. 

While we have not yet carried out detailed kinetic measurements on the rate of photocorrosion, our impression is that the process is relatively insensitive to the specific composition of the strontium titanate. Trace element compositions, obtained by spark-source mass spectrometry, are presented in Table I for the four boules of n-SrTi03 from which electrodes have been cut. Photocorrosion has been observed in samples from all four boules. In all cases, the electrodes were cut to a thickness of 1-2 mm using a diamond saw, reduced under H2 at 800-1000 C for up to 16 hours, polished with a diamond paste cloth, and etched with either hot concentrated nitric acid or hot aqua regia. Ohmic contacts were then made with gallium-indium eutectic alloy, and a wire was attached using electrically conductive silver epoxy prior to mounting the electrode on a Pyrex support tube with either epoxy cement or heat-shrinkable Teflon tubing. 

The second type of sample is composed of single crystals [19]. The crystals are plate-like (flakes) and have sub-millimeter size. They were glued by silver epoxy to the sample holder by one of their side faces. The opposite face of the flakes was used as a needle to gently touch the noble metal counter electrode in liquid helium. In this way we tried to make, preferentially, a contact along the ab plane. On average in... 

For the conductivity measurements, the films were deposited on glass slides which had been precoated with 1,000-A-thick stripes or pads of evaporated silver metal. The deposited silver metal was bonded to silver wires with silver epoxy which were in turn connected to tungsten connectors by platinum wires (Fig. 1). A high-vacuum glass apparatus was constructed with which... 

What actually occurs during these final preparation procedures can be inferred from resistance measurements taken on pellets within the furnace. A DC technique with current reversal was used for these measurements. Four platinum leads were attached to the pressed pellet sample with silver epoxy. The epoxy was covered with a layer of protective ceramic paste. (8) To compensate for induced thermal emf s, an average of the forward and reversed current directions was... 

Tra-Duct [Tra-Con] Conductive nickel or silver epoxy adhesives. 

Most IC materials are either solder pastes or silver epoxies. Besides providing an electrical path for a circuit, they can also be used to attach radio frequency shields. 

Silver epoxies consist of silver flakes suspended in an adhesive carrier. The materials are designed so that the silver flakes touch each other when cured and provide an electrically conductive path. Generally, silver epoxies have lower conductivity than solder paste, but usually have the advantage of a reflow temperature lower than the temperature required for solder paste. 

They can also be designed with lower modulus of elasticity and various coefficients of thermal expansion to suit applications. Silver epoxies also feature good thermal conductivity. 

Surface-mount adhesives, silver epoxy, solder paste, and comer and edge bonding... 

DieMat DM 6030 Series, High thermal conductivity silver epoxy adhesive, DieMat Product Data Sheet. March 19, 2008. 

The recticulated vitrous carbon is cut into 2mm x I mm X 0.5 mm. A copper connective wire (0.3 mm) with thermoplastic insulation is attached to the RVC by silver epoxy. The silver epoxy is allowed to dry overnight in a vacuum oven (70 C) and is then insulated by nonconductive epoxy. The polymeric film is deposited from a degased solution of monomeric porphyrin using the same procedure as described for the preparation of a single-fiber sensor. After film formation, the electrode is dried in a vacuum oven at 40 C and then dip-coated in 1% Nafion in alcohol. The biological cells suspended in 3 ml culture medium are placed dropwise onto the sensor (sterilized by UV light) located in a 60 x 15 mm tissue culture dish. The concentrated cell suspension on the sen.sor is incubated for approxi-... 

Fig. 20 The variable temperature electrode employed by Korzeniewski (see Ref. [177]). (i) Rdisc (ii) silver epoxy ...

Fig. 7 Schematic diagrams of the microchip electrophoretic system with the movable contactless-conductivity detector (A) along with a detailed design of the movable electrode system top (B) and bottom (C) views as well as cross-sectional views without (D) and with (E) the PMMA separation chip, (a) Run buffer reservoir, (h) sample reservoir, (c) unused reservoir, (d) movable electrodes, (e) separation chaimel, (f) sample waste reservoir, (g) PMMA chip, (h) conductive silver epoxy, (0 PVC clamps, (/ ) copper wires, (k) aluminum foil electrodes, and (/) Plexiglas plate (Reprinted with permission from Ref. [9])...

Typical in situ electrical resistivity specimens. (a) Nomex Aramid made with silver-epoxy paint. 

The method of choice for the measurement of resistance when one wishes to avoid potential drops across the contacts is the four-probe method. In this method, four low-resistance contacts are made diagonally (in the shape of a diamond) on the polymer surface using thin wires fixed to the surface by preparations such as silver epoxy (soft cure) or Electrodag. A constant current is passed through two contacts and the potential difference is measured across the other two. From this the resistance or conductivity may be calculated. The condition to be satisfied in this measurement is that the thickness of the polymer film (or pellet) should be much less than the length. 

In photothermal spectroscopy, a sensitive fast response thermistor is attached to the back of the test electrode with silver epoxy (to achieve a good thermal contact), whilst an identical thermistor is placed in the bulk of the solution [27]. These thermistors are then configured as two branches of a balanced Wheatstone bridge and the electrode is illuminated with a chopped monochromatic light beam. The small periodic changes in the electrode temperature are then detected... 

Working electrodes were prepared as follows Pt disks (dia =3.3 mm) were heat-sealed onto the surface of Kel-F cylinders by melting the Kel-F around the disk with a heat gun and then physically pressing the Pt into the heat-softened surface. Electrical contact was made to the back of the Pt disk with silver epoxy (Epo-Tek 410E, Epoxy Technology). The electrodes were then polished as described previously (21). 

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