Solder Connection

Solutions in Soldering Technology

RMA-390DH3 Fineline Solder Paste

ALPHA® RMA390DH3 is a rosin based solder paste designed for surface mount processes and other demanding electronics assembly applications where post reflow cleaning is not required. Because of its unique activator package and other special additives, RMA390DH3 is suitable to remain on the circuit board without cleaning.

Key Products Features & Benefits: 

  • Excellent rheology
  • Unique Flux Vehicle
  • High sir
  • Wide print process window
  • High tack
  • Excellent no clean reliability
  • J-STD Classification: ROH1


Product Number : RMA390DH3

Prod. No. 21513
Alpha RMA390DH3 62/36/2 700g

Prod. No. 21578
Alpha RMA390DH3 63/37 500g


Q - How long can l leave the paste container out at room temperature?
A - You can safely leave the paste out on the bench for the duration of your shift.

Q - Do we need to return to fridge after use?
A - If you are going to continue the next day, then no you should not return the paste to the fridge.

Q - How long do l have to leave the paste before l can use it once taken from the fridge?
A - Always allow the paste to come up to ambient temperature, take it out of the fridge the night before seems to work well.

Q - I need to achieve better print definition, should l look at a finer solder particle size?
A - Your first call should be to your stencil manufacturer, and see if the aperture design is correctly optimised for you design and process capabilities?

Q - Is a framed stencil a more stable print platform than a stretched foil ?
A - Not today, most foil tensioning systems will give similar print stability as would framed stencils. Much is down to cost or personnel choice.

Q - Once printed how soon before l need to place my components?
A - Always place components before the end of your shift, this has to be good practice.

Q - What kind of print speeds can l use.
A - Always refer to the Technical Data sheet for the specific product, but, to initiate and create excellent shear thinning of the solder paste and promote paste roll a suggestion would be to start at 40mm/s and adjust according to process requirements, changes to pressure / release speed / release height could also be considered to achieve maximum performance.

Q - What is colophony and can it cause any health issues?
A - Colophony is a generic term for rosin, this is the sap or sticky substance that derives from pine and spruce trees. Its "stickiness" lends itself to being used in a wide range of products. We have traditionally used this product in fluxes due to these specific properties it can however lead to breathing difficulties and skin sensitivity. Always use fume filtration when soldering and change filters regularly.

Q - What is the difference between rosins and resins?
A - The terms are often used interchangeably, but rosin is a naturally occurring substance, and resin is either a modified rosin or completely synthetic material. Rosins are plant based products and are subject to more natural variation than resins, however resins are commonly used in newer flux formulations due to their more consistent performance.

Q - Do I need to change my printing process when I go to finer printing from size 3 to size 4 paste?
A - Generally when changing from T3 to T4 there is not much difference in printing setup. Depending upon the paste used you may have to make slight adjustments to print parameters such as release speed as aperture fill is greater with finer powders on small apertures but this is just to optimise the print as you would do when changing any paste. It’s by no means certain you will need to do this but it may give you further benefits.

Q - Do I need to change my printing process when I go to Ultra Fine printing from size 4 to size 5 paste?
A - The biggest change will be going to PS5 and its not so much the printing parameters changing but the stencils are invariably a lot thinner and so you need good support and setup such as making sure you have a release distance of 3 mm set (the distance over which release speed is controlled as the stencil acts more like a drum skin) I would also run with the minimum pressure to avoid stencil damage (coining) this is as most PS stencils are <100µm typically 75µm in thickness. It’s not as bad with PS4 as most stencils are in the 100µm or slightly above range and are more robust.

In all cases (can’t really think of an exception) smaller powder sizes go hand in hand with printing smaller features. Smaller features as we approach Area Ratio 0.66 and in some cases people try to/do operate in the region of AR 0.6-0.66 mean that the printing process has to be good, you have to “respect the fundamentals” i.e. board support, calibration of such things as print height, squeegee condition, decent PCB quality, registration etc.

Again more a feature of small apertures rather than the powder size of paste itself you may need to look at what is your maximum ‘abandon’ time with any paste if you run a start stop process and work to it i.e. don’t exceed and use automatic under screen cleaning where needed. Smaller apertures tend to ‘clog’ more readily and so may need a more frequent aperture clean regime.

Associated Products

Reliacore 15 Leaded Solder Wire

More Info

Safewash SWA

More Info

Waste Paste Buckets

More Info

OM-338T Lead-Free Solder Paste

More Info