HASL | Hot Air Solder Leveling Surface Finish- HXDcircuit

What is HASL?

hasl surface finish

HASL (Hot Air Solder Leveling) is a common and mature PCB surface finish process.Its main purpose is to form a solderable and oxidation-resistant solder layer on copper pads, making component assembly easier and more reliable.

Typical HASL Process Flow：

Pre-cleaning The PCB is cleaned to remove oil, oxides, and contaminants. This ensures a clean copper surface and improves solder wetting.
Preheating The board is heated evenly. This reduces thermal shock when it enters the hot solder bath and helps the flux work more effectively.
Flux Coating Flux is applied to the PCB surface. It removes remaining oxides and lowers surface tension to improve solder quality.
Solder Coating The PCB is dipped into a bath of molten solder (leaded or lead-free). This covers all exposed copper pads and holes with solder.
Air Knife Leveling As the PCB leaves the solder bath, high-pressure hot air (air knives) blows away extra solder. This makes the solder thickness on the pads more even.
Post-cleaning After the solder cools and hardens, the PCB is cleaned again. This removes flux residues to ensure the board is clean and reliable.

PCB Certifications

HXD HASL Process

1Layer with HASL LF

FR4 Material with HASL LF– Cost-effective and ideal for beginner projects, quick prototyping, training, and educational use. HASL LF has excellent solderability for repeated testing and manual solder experiments.

2Layer Aluminum PCB

Offers improved routing flexibility and electrical performance compared to standard single-layer MCPCBs—ideal for more complex lighting designs.

2Layer with 0.6mm thin thickness

Better Flexibility Than Standard Thickness – Slight bending tolerance makes it suitable for tight assembly structures.

6Layer roud PCB with long routing

Our 6-layer round PCB combines a complex circular shape with high-density 4/4mil track

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Why Choose HASL?

High Cost-Efficiency

Among all surface finish processes, HASL is the lowest cost, making it suitable for large-scale production.

Excellent Soldering Performance

The coating is made of actual solder (Tin-Lead or Lead-free alloy). This provides better wetting than other treatments, making it easier to create strong, reliable solder joints.

Long Shelf Life

HASL offers better protection against oxidation compared to OSP or Immersion Silver. This means your boards can be stored for a longer time without losing quality.

Early Defect Detection

During the process, the PCB is exposed to temperatures up to 265°C. This high heat acts as a “stress test,” helping you find potential delamination (layer separation) issues before you mount expensive components.

Leaded HASL vs Lead-free HASL

Whether using leaded or lead-free solder, the HASL process follows the same core principle.The main differences between Leaded and Lead-free are the chemical composition, environmental standards, and the heat required during processing.

Features	Leaded	Lead-Free
Alloy Composition	63% Sn / 37% Pb	99.3% Sn / 0.6% Cu
RoHS	Non-compliant	Compliant
Melting Point	Lower	Higher

Lead-free HASL uses alloys with a higher melting point than traditional leaded solder. Because the process is hotter, the PCB must be able to handle the extra heat.

Therefore, we recommend using high-temperature laminates (high-Tg materials) for lead-free HASL. This prevents the board from warping or damaging during production.

Although lead-free HASL provides better flatness, it is not ideal for very small SMDs (0805 and below) or fine-pitch components.

HASL (Hot Air Solder Leveling) PCB Surface Finish

Reliable Hot Air Solder Leveling for leaded and lead-free PCBs. Ensures excellent solderability, long shelf life, and stable performance for all your PCB needs.