Powder, composite solders
and solder pastes(cream)

Having wide experience in preparation of powders and granules UralNR applies these materials to manufacture of welding alloys and solderi pastes. The solder alloys by way of powders and granules will be used for the soldering of goods for the most miscellaneous forms and materials. UralNR designs new kind of soldering alloys and investigates a complex of their properties. For this purpose equipment for manufacture of solder alloys (plant for atomisation, classification and pressing of a powder, melting pot of powders and fluxes) is used. Investigation of properties of solder pastes and junction in different range of temperatures and humidity (gauging of viscosity and adhesion, durability from -60 up to 600, spreading and other) is applied for this purpose.

Solder pastes

It is a homogeneous mix of solder powder and flux. The flux includes different components preventing separation of a powder and flux provides significant viscosity. Solders pastes are introduced in very wide range of combinations from different solder alloys, fluxes, viscosities and sizes of particles and are suitable for applying in the different purposes. In Table 1 the sorts of solder alloys and their basic performance are represented. In Table 2 and Table 3 the classes and sizes of particles of a powder of solder alloy used to make pastes are represented. In Table 4 the chemical compositions of solder alloys, and in Table 5 the chemical compositions of brazing alloys are represented. One of the principal advantages of usage of soldering alloy by way of solder pastes is in possibility of a precise batching of an indispensable amount of solder alloy at surface-mount technologies both plotting from cartridges and squirts.

Application

Fig. 1. The soldering of auto radiator and bellows-sealed.

The general application of pastes is soldering of electronics components at surface mounting of hybrid circuits and printed circuit boards. Solder pastes are applied also at mounting of power electrical networks. In Table 6 and in Table 7 the areas of application of solder pastes are introduced. Pastes will be widely used for the constructional soldering of fitting for cool and hot water, gas and vacuum communications. The great quantity of pastes will be used for the soldering of automobile radiator and air conditioners. Pastes on a base of a powder of soldering alloy (Sn50%Pb50%) will be used for the soldering of a radiator metal paper to a corrugation, and on a base of a powder -600 of a brazing alloy (CuSnPNi) for the soldering of funnels of refrigeration and corrugation. Pastes are divided for the soldering by soft and hard alloys. The soft alloys are soldering alloys with a melting temperature up to 300C, whereas the brazing alloys have temperature of the soldering above 500C. There is a small number of soldering alloys with a melting temperature in the range 300-500C. Such soldering alloys concern into the semi-hard class. The soft alloys as a rule are prepared from alloys on a base of tin whereas brazing alloys - on a base of copper, aluminum and nickel.

Delivery of solder pastes and brazing alloys

Solder pastes are delivered in syringe with a capacity 5 ml (20 grams), 10 ml (25-50 grams) and 150 ml (20-600 grams). The syringe are completed by needles with a diameter of holes 0,8; 1,0 and 1,2 mm. Pastes also are delivered in polyethylene hermetic banks with a capacity 0,5 and 1 kg. The powders of solder alloys are delivered in hermetic parcels in environment of nitrogen or argon in amounts of 3-10 kg or metal tare with a capacity up to 40 kg.

Fig. 2. Methods packing of pastes

Composite soldering alloys and solder pastes

Fig. 3. Forms of solder alloys

It is a new aspect of a solder material representing a mix solder powder and a flux in the solid or fluidic forms. The existing tubular soldering alloys containing rosin have deficiencies (strong sputtering of soldering alloy at a boiling of rosin). It is caused to dissimilarity of allocation of metal and flux. Composite soldering alloy is more homogeneous system from a fine powder of a flux and alloy. For example, the composite soldering alloy "Ntrmm-16" is represented by way of a wire with diameter 0,5 - 6 mm obtained by pressing of a powder of the soldering alloy Sn61Pb39 and powders of rosin and other active components. It is known also that soldering alloys usually have lower durability than base. Some our solder pastes contain along with particles of solder alloy the fine-dyspersated impurities of refractory (higher than a melting temperature of soldering alloy) particles or ceramics. These impurities allow to increase durability and yield stress of soldering connection. The solder alloy can be produced in different types: paste, granules, wire and metal foil. The soldering alloys with low temperature of the soldering and high temperature of the unsoldering are recently designed. For example, the soldering alloys on a base of gallium have temperature of the soldering 20-35 0C and temperature of the unsoldering above 500C.

Development and testing of soldering pastes

The firm is engaged permanently in development of new types of solder alloys and solder pastes. For this purpose there is indispensable technological and analytical equipment. In particular the developments on creation of soldering pastes having powders dimensioned of particles 25-15 microns and even 15-5 microns will be carried out. The methods permitting to obtain such powders in amount up to 50 % from total mass are designed. There is a burst machine of a type MIP-5000, permitting to conduct tests the mechanical characteristics of solder mounting in a range of temperatures from -60 up to + 600C. There is also laboratory plant for gas-dynamic classification of fine (less than 20 microns) powders.

 

Fig. 4. Plant MIP-5000

The detailed characteristics of soldering pastes (Table 1-7)