Silver-containing conductive preparations of DODUCO GmbH

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Decades of experience in the area of production of silver-pigmented conductive preparations and close cooperation with the customer have enabled DODUCO to develop general and special problem solutions according to the customer's wish. This way, different conductive products resulted, the properties of which have been adjusted to different requirements.

 

DODUCO's range of precious-metal-containing (silver-pigmented) conductive preparations includes:

 

Silver conductive varnishes Silver conductive pastes Silver conductive glue

 

Deviating delivery forms and packagings are possible on request.

 

 

Silver conductive varnishes

DODUCO's silver-pigmented conductive varnishes are liquid, solvent-containing, physically drying varnishes. Depending on the area of application (carrier material, drying requirements), there are mostly two types distinguished:

• Conductive varnishes on acrylate-resin basis and
• Conductive varnishes on nitrocellulose basis

At a silver share of approx. 40 % silver (exceptions are possible) in the form of silver powder or silver flakes from own production, DODUCO's silver conductive varnishes are characterised by high electrical conductivities at low viscosities. The liquid conductive varnishes can be applied to the carrier materials by brush, roller or submersion. If a spray application is desired, the conductive varnish should be mixed with the corresponding diluent (information on the diluent is available on request). Drying takes place by evaporation of the solvents contained in the temperature range between 20-100°C (on demand, higher temperatures are possible as well).

 

DODUCO's product range currently contains the following conductive varnishes:

 

AUROMAL® 35
Base	Acrylate resin
silver-content	70 %
Viscosity	100-200 mPas
Surface resistance	< 100 mOhm/cm² at 150°C
Properties/use	Hard, well-conductive silver layer, suitable for galvanic reinforcement

 

AUROMAL® 38
Base	Acrylate resin
silver-content	40 %
Viscosity	40-50 mPas
Surface resistance	400 mOhm/cm² at RT   < 100 mOhm/cm² at 100°C
Properties/use	hard, well-conductive silver layer

 

AUROMAL® 50
Base	Nitrocellulose
silver-content	45 %
Viscosity	30-50 mPas
Surface resistance	< 200 mOhm/cm² at RT < 50 mOhm/cm² at 100°C
Properties/use	Level surface, particularly suitable for galvanic reinforcement

 

AUROMAL® 50L
Base	Nitrocellulose
silver-content	45 %
Viscosity	50-70 mPas
Surface resistance	< 200 mOhm/cm² at RT < 50 mOhm/cm² at 100°C
Properties/use	Hard, well-conductive silver layer, suitable for galvanic reinforcement

 

 

The benefit of the silver conductive varnishes as compared to the pastes is in simple processing and quick drying. Furthermore, they have a strong, good adhesion to the base and very good electrical and thermal conductivity.

 

DODUCO's silver-pigmented conductive varnishes are used in:

• shielding of electromagnetic waves in the area of electrical engineering and electronics
• Production of a contact in the area of electrical engineering and/or hobby electronics (e.g. electronic toys)
• Repair of conductor tracks / improvement of printed circuits
• Repair of heating conductors (rear window heatings)
• Repair of antennas
• Metallisation of non-conductive bases for galvanic further processing

 

Silver conductive pastes

The also physically drying silver-pigmented conductive pastes of DODUCO's range have a much higher viscosity than the conductive varnishes. This is caused by higher shares of silver (approx. 60%) and use of polymer basic components for formation of polymer compounds / design of the polymer structure. The silver used in the silver conductive pastes in the form of silver powder or silver flakes is also from the DODUCO-internal production.

 

The silver-pigmented polymer thick-film pastes are characterised by good electrical and thermal conductivity as well as good adhesion and bending resistance while being highly flexible. The application of conductive pastes preferably takes place by screen printing, with selection of the mesh size varying depending on printing pattern, layer thickness and base. Drying and curing may take place in circulation air dryers, IR-dryers or special tunnel furnaces.

On remand, the silver-pigmented conductive pastes can also be adjusted to different processing techniques (e.g. pad printing). The chemicals required for this may be purchased from DODUCO on request.

 

DODUCO's product range currently contains the following conductive pastes:

 

AUROMAL® 141
Base	Acrylate resin
silver-content	63 %
Viscosity	1,5-3,0 Pas
Surface resistance	< 50 mOhm/cm² at 150°C
Properties/use	Mechanically high-strength coatings with very good conductivity, Good adhesion on plastic

 

AUROMAL® 145
Base	Acrylate resin
silver-content	65 %
Viscosity	10-15 Pas
Surface resistance	< 30 mOhm/cm² at 150°C
Properties/use	thixotropic, very good conductivity, Good adhesion on plastic

 

AUROMAL® 170
Base	Mixed polymer
silver-content	60 %
Viscosity	3,5-5,0 Pas
Surface resistance	< 50 mOhm/cm² at 150°C
Properties/use	Well-conductive, flexible layers with high abrasion resistance, Good adhesion on films

 

 

The benefit of silver conductive pastes as compared to the varnishes is in the better adhesion to plastic bases as well as films. I spite of high demands by increased flexibility, the layers remain stable and retain their very good conductivity.

 

DODUCO's silver-pigmented conductive pastes are used in:

• production of conductor tracks on membrane keyboards
• production of circuits on PCBs

 

Silver conductive glue

In addition to silver conductive varnishes and silver conductive pastes, DODUCO also produces silver conductive glues. Silver-pigmented conductive glues are used to apply construction elements to different carrier materials with conductive contacts. The adhesive technique offers essential benefits as compared to soldering, since lower curing temperatures permit connecting even heat-sensitive parts to each other conductively. Additionally, the higher flexibility of the bonding improves ageing behaviour of the material/part.

 

DODUCO's delivery range contains two types of silver-pigmented conductive glues:

• Single-component conductive glue
• Two-component conductive glue

 

Single-component conductive glues are ready-to-use systems with long processing times. Curing takes place within 15-60 min. at temperatures between 120-200°C. In two-component conductive glues, in contrast, are mixed directly before use and then must be processed speedily. The processing time is approx. 4 hours, depending on ambience conditions. Curing can be thermally sped up.

Silver-pigmented conductive glues are applied by screen printing or dispenser.

 

DODUCO's product range currently contains the following conductive glues:

 

AUROMAL® K10
Base	Epoxy resin
silver content	70 %
Viscosity	15-25 Pas
Surface resistance	< 100 mOhm/cm² bei 200°C
Properties/use	thixotropic, solvent-free, High-strength bonding for transferring high current and heat volumes to ceramics or metal

 

AUROMAL® K11
Base	Epoxy resin
silver content	70 %
Viscosity	20-30 Pas
Surface resistance	< 100 mOhm/cm² at 80°C
Properties/use	thixotropic, solvent-free, fixed, flexible, well-conductive connections for transferring high current and heat volumes to PCBs, ceramics or metal

 

AUROMAL® K20
Base	Epoxy resin
silver content	70 %
Viscosity	10-20 Pas
Surface resistance	< 50 mOhm/cm² at 200°C
Properties/use	thixotropic, solvent-free, firm, well-conductive connections for use on printed circuits of ceramics, metal or plastics

 

AUROMAL® K5-A80
Base	Epoxy resin
silver content	80 %
Viscosity	20-30 Pas
Surface resistance	< 100 mOhm/cm² at 80°C
Properties/use	solvent-free, well-conductive connections, suitable for plastics, mechanically very strong connections as an alternative for soft-soldering

 

 

Special features of DODUCO's silver-pigmented silver glues are:

:

• very good conductivity
• low-stress properties
• high strength
• good heat conductivity
• no solvents
• temperature stability