Reflowing solder paste

July 10, 2019
2 minute read.

What is solder paste?

Alloys, Flux, T4, T5, Wetting - Not sure what this all means? Here's a crash course on solder paste.


We currently offer two types of solder paste alloys in T4 and T5 particle sizes:

Tin Bismuth Silver (Sn42 Bi57.6 Ag0.4) is RoHS compliant and is meant for our conductive inks. Tin Lead (Sn63 Pb37) is meant for factory fabricated boards with a HASL finish.

Before reflow soldering on the V-One, check the following:

  • Is your board larger than 3" x 4" ( 76.2 mm x 101.6 mm) ?
  • Are you reflowing large components like connectors?
  • Does your board have multiple ground planes?

If you said YES to any of the above, then the automatic REFLOW mode may not work correctly. The board will act like a large heat sink and will not reach the peak reflow temperatures. Instead, you should use the MANUAL mode.

Tip: If your board will act like a large heat sink, do a MANUAL reflow instead (See below)

Tin Bismuth Silver (Sn42 Bi57.6 Ag0.4) Profile

Automatic reflow profile for Tin Bismuth Silver (Sn42 Bi57.6 Ag0.4)

Soak Temp. Soak Time Peak Temp. Peak Time
140°C (284°F) 45 seconds 190°C (365°F) 30 seconds

Tin Lead (Sn63 Pb37) Profile

Automatic reflow profile for Tin Lead (Sn63 Pb37)

Soak Temp. Soak Time Peak Temp. Peak Time
180°C (356°F) 45 seconds 220°C (428°F) 30 seconds

Manual Reflow

A manual reflow requires the user to place close attention to the board as it is reflowing. To perform a manual reflow:

  1. Clamp your board on the heated bed.
  2. Enter Heat > Manual mode.
  3. Set the temperature to the soak temperature.
  4. Hold for 1-2 minutes to let the whole board reach the temperature.
  5. Set the temperature to the peak temperature.
  6. Observe the solder paste closely.
  7. As soon as the last pad finishes reflowing, hit STOP to start cooling the board.
Solder Alloy Soak Temp. Peak Temp.
Tin Bismuth Silver 140°C (284°F) 190°C (365°F)
Tin Lead 180°C (356°F) 220°C (428°F)

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