No Clean RMA Solder Creams

RM92

• Screen printing and stenciling grades
• Grades suitable for fine pitch applications available
• Excellent resistance to preheat slump
• Good tack performance and wetting
• Residues may be left uncleaned

PRODUCT RANGE
Multicore RM92 solder creams may be supplied with powder made from most solder alloys in the Multicore Product Range. The most common alloys used are Sn60, Sn62 and Sn63 conforming to the purity requirements of J-STD-006 and EN 29453. Minimum order requirements may apply to certain alloys and powder particle sizes.
   A wide range of metal contents and solder powder particle size distributions may be ordered but most applications will be served by the following recommended products:

For dispensing applications, the equivalent Multicore RM89 solder creams are recommended.
   If clear residues are preferred, the user should evaluate the Multiprint range. Customers wishing to print at high speed should consider Multicore RP10 solder creams.

RECOMMENDED OPERATING CONDITIONS
APPLICATION: The appropriate grades of Multicore RM92 solder creams have been specially formulated for application by screen printing and stenciling.  They do not require the addition of thinners either before use. It is recommended that products shipped in jars should be gently stirred for 15 seconds before use.

REFLOW: Any of the available methods of heating to cause reflow may be used including IR, convection, hot belt, vapour phase and laser soldering. It is not practicable to recommend an ideal reflow temperature profile for all situations. However, the following shows an example profile which has given good results in practice.

 Multicore RM92 solder creams have been specially formulated to show a marked resistance to preheat slump. They can tolerate the longer preheat times often required for large surface mounted devices or densely populated boards. Furthermore, Multicore RM92 solder creams are less liable to char during reflow at the elevated temperatures required for some solder alloys.

CLEANING: The residues from Multicore RM92 solder creams may be left on the PCB in many applications since they do not pose a hazard to long term reliability. However, should there be a specific requirement for residual removal, this may be achieved using conventional cleaning processes based on solvents such as Multicore Prozone, or water containing suitable saponifying agents such as Multicore PC85.

SOLDER POWDER: The solder powder for Multicore RM92 solder creams is produced by atomising alloys conforming to the purity requirements of J-STD-006, EN 29453 or other national and international standards where relevant.

   Careful control of production processes ensures that the solder powder is at least 97% spherical (aspect ratio < 1.5) and contains less than the minimum level of contaminants that would adversely affect solder cream performance. A typical maximum oxide contamination level of 80ppm (expressed as oxygen in the solder) is regularly achieved or bettered.

SOLDER CREAM MEDIUM: The flux for Multicore RM92 solder creams is a RMA type showing the following characteristics. Test reports are available on request.

SOLDER CREAM: The properties of a solder cream depend in part on the metal content, the solder alloy and the solder powder particle size range. In general terms, increasing metal content reduces the tendency to slump and reduces the tackiness of the solder cream while the solder balling performance improves. Using solder alloys with increased density has the same effect as reducing the metal content.
   It is common practice to characterise the rheology of solder creams by making a viscosity measurement at a single specified shear condition. Increasing metal content increases the measured value and at higher metal contents, decreasing the mean solder powder particle size can have the same effect.
   The characteristics of Multicore RM92 solder creams which confer their superior slump performance also increase their sensitivity to the conditions of sample preparation before making Brookfield viscosity determinations. Excessive stirring before testing can lead to erroneously low values for viscosity. A more informative indication of the rheological properties of solder creams is provided by a plot of viscosity versus shear rate and these typical results for a selected Multicore RM92 solder cream are shown in the following graph.
Typical properties of selected Multicore RM92 solder creams are as follows. Full details of test methods will be supplied on request.

VISCOSITY DATA FOR SELECTED MULTICORE Sn62RM92 SOLDERING CREAMS
Measurements made with the Malcolm Viscometer

• 1kg, 500g or 250g plastic jars with an insert to seal off the surface of the cream

• 1kg vacuum filled cartridges for direct application

Other forms of packaging may be available on request.

SHELF LIFE: Providing Multicore RM92 solder creams are stored at 5 - 10°C tightly sealed in the original container, a minimum shelf life of 12 months can be expected.
Multicore RM92 solder creams have been formulated to reduce separation on storage to a minimum but should it occur, gentle stirring for 15 seconds will return the products to their correct rheological performance.

WARNING: The following information is for guidance only and users must refer to the Material Safety Data Sheets relevant to specific Multicore RA10 solder cream products before use.

FUMES, VAPOURS and PRECAUTIONS: The flux fumes given off at soldering temperatures are irritating to the nose, throat and respiratory organs. Prolonged or repeated exposure to flux fumes may cause sensitisation.
   These materials should always be used in a well ventilated area and suitable fume extraction equipment should be used to extract flux fumes away from the operators.

PROTECTION & HYGIENE: Suitable protective clothing should be worn to prevent materials from coming into contact with the skin and eyes. If the materials come into contact with the skin, the affected area should be cleaned with a proprietary skin cleanser followed by washing with soap and water. If the materials come into contact with the eyes, they should be irrigated thoroughly with running water for at least ten minutes and medical attention sought.
   Eating, drinking or smoking should not be permitted in the working area and hands should be washed thoroughly before eating.

FIRE HAZARDS and PRECAUTIONS: The flashpoint of the solvent used in these materials is high (127°C) but it is combustible. Carbon dioxide, foam or dry powder extinguishers are suitable. High temperatures may produce heavy metal dust, fumes and/or vapours. Do not use water where molten metal is present.

SPILLAGE and WASTE DISPOSAL: Spills of the materials should be scraped up and the contaminated area washed with water.
Waste materials should be stored in closed containers and disposed of in accordance with the relevant local and national regulations.