Sodium hypophosphite

About: Sodium hypophosphite is a research topic. Over the lifetime, 1695 publications have been published within this topic receiving 15932 citations.

Method of forming electric pad of semiconductor device and method of forming solder bump

Abstract: Electroless nickel plating and gold plating is performed on an aluminum electrode in order to construct a highly reliable electrode. The steps are: depositing zinc on the aluminum electrode with zincate treatment liquid containing sodium hydroxide and zinc oxide; immersing it in solution which is prepared by dissolving sodium hypophosphite as a reducing agent into de-ionized water, followed by addition of de-ionized water while adjusting for the pH of 9.0 to 12.0 with sodium hydroxide solution, so as to make a total volume of 1000 ml; nickel-plating the aluminum electrode of the semiconductor device by using electroless nickel plating solution of oxidation-reduction reacting type containing sulfur compound as a reaction promoter, under a condition of the pH at 4.0 to 6.8 and a temperature of 80 to 90° C.; electroless gold-plating by substitutional reaction type; and, electroless gold-plating by oxidation-reduction reacting type, so as to form a nickel film containing phosphor and gold plated films on all aluminum electrodes of the semiconductor device. In this way, a nickel plate film of good electrical conductivity and also a gold plate of a thick film on all aluminum electrodes of the semiconductor device are formed, without resulting in corrosion of the passivation film and the aluminum electrodes.

Effects of pre-treatments on the corrosion properties of electroless Ni-P layers deposited on AlMg2 alloy

Abstract: Amorphous Ni–P layers with 8–10 wt.% phosphorus were deposited by sodium hypophosphite onto AlMg2 type aluminium alloy substrates after different pre-treatments. Prior to the electroless nickel–phosphorus (ENP) deposition in an acetate and lactic acid based nickel bath, the widely applied Zn (zincate) or Ni displacement (Ni strike) pre-treatments for aluminium substrates as well as a non-conventional surface conditioning one (soaking in a warm solution containing only hypophosphite and lactic acid) were all tested and their effects evaluated on the corrosion and other properties of the Ni–P layers developed right afterwards. The surface morphology and structure of the ENP layers were characterized by scanning electron microscopy and X-ray diffraction analysis. Polarization resistances were measured in 0.5 mol dm − 3 Na 2 SO 4 solution at pH 3. Compared to the direct electroless plating on the bare aluminium alloy AlMg2, it was found, that the hypophosphite adlayer (hypophosphite immersion pre-treatment) have also increased the corrosion resistance as the displacement pre-coatings, but without decreasing the deposition rate unlike conventional displacement methods. In the studied ENP deposition systems the decrease of corrosion rate could mainly be attributed to the lower microporosity and smoother morphology of the nickel–phosphorus coatings.

Preparation of cross-linked cellulose nanofibril aerogel with water absorbency and shape recovery

Abstract: Cellulose nanofibril (CNF) aerogels are promising materials for various applications because of their highly porous and ultralight characteristics. The fiber network of CNF aerogels held together by hydrogen bonding and mechanical entanglement of adjacent fibers is easily destroyed when it is exposed to water. In this study, cross-linked CNF aerogels were prepared using maleic acid and sodium hypophosphite as cross-linking agents. In the first step of treatment, CNF dispersed in water was reacted with maleic acid to form an ester linkage. Sodium hypophosphite was then added to the maleic acid-functionalized CNF suspension and the suspension was rapidly frozen using liquid nitrogen. CNF aerogel was obtained after freeze drying. The cross-linking of the cellulose was formed by the reaction between the carbon–carbon double bond of maleic acid-functionalized CNF and hypophosphite. The cross-linked CNF aerogel exhibited good network stability in water and springiness after compression.

Preparation of electromagnetic reflective wool using nano-ZrO2/citric acid as inorganic/organic hybrid coating

Abstract: Nano-ZrO 2 particles were stabilized on wool surface using citric acid (CA) as a crosslinking agent and sodium hypophosphite (SHP) as a catalyst under UV irradiation. The influence of the amount of nano-ZrO 2 on the performance of wool fiber was investigated by the use of Fourier transform infrared spectrophotometer (FTIR), horizontal flammability apparatus (HFA), scanning electron microscope (SEM), water contact angle tester (WCA), reflectance spectrophotometer (RS) and electromagnetic transition instrument (ETI). The possible interactions between nano-zirconia particles, cross-linking agent and wool free radicals were elucidated by the FTIR spectroscopy. Results indicated that the stabilized nano-zirconia enhances the flame retardancy and electromagnetic reflection of wool.

FTIR Spectroscopy Study of the Formation of Cyclic Anhydride Intermediates of Polycarboxylic Acids Catalyzed by Sodium Hypophosphite

Abstract: In recent years, extensive efforts have been made to find formaldehyde-free durable press finishes to replace the traditional formaldehyde-based N-methylol compounds. 1,2,3,4-Butane-tetracarboxylic acid (BTCA) has been the most efficient nonformaldehyde crosslinking agent for cotton, with sodium hypophosphite (NaH2PO2) being the most effective catalyst. In our previous research, we found that a polycarboxylic acid esterifies cellulose through the formation of a five-membered cyclic anhydride intermediate by the dehydration of two adjacent carboxyl groups. In this research, we use Fourier transform infrared spectroscopy (FTIR) to study the formation of cyclic anhydride intermediates by BTCA and poly(maleic acid) (PMA) with and without the presence of NaH2PO2. In the absence of NaH2PO2, BTCA forms the cyclic anhydride only when the temperature reaches the vicinity of its melting point. In the presence of NaH2PO2, however, the anhydride forms at much lower temperatures. We have found that NaH2PO2 weakens the...