SMT for tiny components

Tiny Component

During the SMT process of PCB, special measures are required to ensure placement accuracy, soldering quality and process stability when handling particularly small components (such as 0201, 01005 or even smaller packages, or fine pitch QFN, CSP, etc.). Chee Mau achieves this through the following measures:

1. Solder paste printing control

Fine pitch stencil: Use laser cut or electroformed stencil, the thickness is usually 0.08~0.1mm, and the opening accuracy is ±10μm.

Solder paste type: Choose solder paste with smaller particle size (such as Type 4 or Type 5, particle diameter 5~15μm) to improve printing uniformity.

Printing calibration: Use high-precision visual systems (such as 2D/3D SPI) to monitor solder paste volume and position offset in real time.

2. High-precision placement

SMT machine requirements:

--Accuracy: Placement head with at least ±25μm (CPK≥1.33).

--Vision system: high-resolution camera (such as 30μm/pixel) with multi-light source illumination (side light, coaxial light).

--Nozzle adaptation: Use customized nozzles (such as vacuum nozzles or electronically controlled nozzles) to ensure the stability of small component grabbing.

Mounting pressure control: Dynamic pressure adjustment (such as 5~20g) to avoid damage to fragile components.

3. Reflow process optimization

Temperature curve: Use nitrogen protection for reflow to reduce oxidation risk; accurately control the heating slope (1~2°C/s) and peak temperature (usually 235~245°C).

Anti-drift design:

--Pad symmetry: avoid tombstones caused by uneven surface tension.

--Bottom filler: pre-dispense glue to fix CSP/BGA components.

4. Inspection and rework

AOI (automatic optical inspection): high-magnification optical inspection (such as 50μm resolution) to check for defects such as cold solder joints and bridging.

X-ray inspection: 3D tomography for hidden solder joints (such as QFN bottom pads).

Laser rework: Local heating and repair of micro components to avoid thermal damage to surrounding devices.

The core of SMT for tiny components lies in "precision control" - Chee Mau matches high-precision equipment and strict process parameters in every link from printing, mounting to reflow soldering to meet customer needs.