PCB board solderability testing

PCB board solderability testingIt is an essential step in the SMT process, and its core is to verify the physical and chemical properties of the solder interface through scientific means, ensuring a strong and reliable connection between the solder and the substrate. Through testing, companies can detect material defects in advance, optimize process parameters, and ultimately improve product yield and long-term reliability.

PCB board solderability testingIt is an experimental method for quantitatively evaluating the wetting ability of solder, and the detection method is as follows:

Immersion tin method

Immerse the test sample (such as component pins or PCB pads) into molten solder, measure the change of wetting force over time through sensors, and calculate the wetting speed and wetting area.

Standard requirements: Wetting time ≤ 2 seconds, wetting area ≥ 95% (such as IPC-J-STD-020 standard).

Solder ball wetting test

Place the solder ball on the heated solder pad and observe whether it spreads evenly after melting. If the solder ball shrinks or forms a spherical shape, it indicates insufficient solderability.

X-RayTesting method

In SMT production lines, AOI (Automatic Optical Inspection) orX-RaydetectionAfter reflow soldering, indirectly evaluate the wetting quality of the solder joint.

The main verification items of weldability testing

Surface treatment quality

Whether the plating of PCB pads (such as the thickness of ENIG gold layer and the integrity of OSP film) is uniform and free of oxidation;

Whether the plating (such as tin lead alloy, nickel palladium) of component pins (such as QFP, BGA) meets the soldering requirements.

Material pollution and oxidation

Whether the solder pads or components have oxidized or left soldering flux due to improper storage (such as high temperature and high humidity environment);

Whether the solder paste has decreased wettability due to moisture absorption or poor printing.

Welding process parameters

Is the reflow soldering temperature curve reasonable (such as preheating zone heating rate, peak temperature);

Is the flux active enough to effectively remove oxides.

long-term reliability

Verify the weldability stability of materials in harsh environments through accelerated aging testing, such as testing after high-temperature and high humidity storage.