Powder, composite solders
and solder pastes(cream)
 Having
wide experience in preparation of powders
and granules UralNÅÒRÀÌÌ 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.
UralNÅÒRÀÌÌ 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°Ñ, 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
ÎÊÑ-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 300°C, whereas
the brazing alloys have temperature of
the soldering above 500°C. There is a
small number of soldering alloys with
a melting temperature in the range 300-500°C.
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
"Nåtràmm-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 500°C.
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 + 600°C. 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)
|
