How to solve the problem of dry solder paste?

For solder paste drying problem, you can start from storage, use, process, environment, material selection, emergency treatment and other aspects, the following provides you with systematic solutions:

I. Analysis of the causes of dryness

I. Analysis of the causes of dryness

II. Targeted Solutions

Storage Management

Temperature control

Unopened solder paste: Refrigerate at 0-10°C, avoid freezing (to prevent separation of components)

Opened solder paste: 20-25 ℃ sealed storage, use up within 48 hours

Sealing Measures

Put the lid on immediately after use and press the inner lid tightly.

Recommended sealing of solder paste jar bottle and lid with adhesive tape (to reduce the risk of oxidation)

Usage specifications

Re-warming process

Refrigerated solder paste should be left at 25℃ for 4 hours (heating is not allowed to speed up the rewarming process).

Stirring after rewarming: low speed (500-800rpm) clockwise stirring for 1-2 minutes.

Printer management

When adding solder paste, "small amount, many times" (single addition <1/3 of the length of the squeegee).

Stopping the press for more than 60 minutes to cover the paste and switch off the squeegee pressure.

Process optimisation

Environmental control

Workshop temperature and humidity: 23 ± 2 ℃, 50-60% RH (equipped with constant temperature and humidity equipment)

Reduce the air flow (avoid the vents blowing directly on the printing machine)

Printing parameter adjustment

Squeegee pressure: 0.2-0.5kg/cm² (excessive pressure will accelerate solvent evaporation)

Printing speed: 20-50mm/s (too fast leads to paste shear thinning)

Material selection

Anti-drying solder paste with slow evaporating solvents (e.g. rosin-based/resin-based fluxes).

High antioxidant formulation (e.g. addition of benzotriazole inhibitors)

Emergency treatment

Minor crusting: Remove the hardened layer with a clean squeegee and continue to use the paste underneath.

III. Preventive testing methods

IV. the common misunderstanding

Wrong practice: use a hot air gun to heat back to temperature → lead to flux evaporation

Misconception: "refrigeration can be stored indefinitely" → the actual shelf life of 4-6 months

Over-reliance: add diluent → may change the reliability of the solder joints, dilution process and quality can not be controlled

V. Manufacturer technical support

Require vendors to provide "solder paste storage and use of instructions

Regular printing process verification (recommended quarterly)

Apply for free sample testing (focusing on verification of open time indicators)

Management effect:

Through systematic management, can reduce the probability of dry solder paste more than 90%

Enhance printing yield (typical case: a mobile phone motherboard manufacturer through humidity control + process optimisation, solder paste waste reduced by 37%)

The above solution combines measures in storage, use, process, environment, materials and other aspects, which can effectively solve the problem of solder paste drying.