Surface Mount Technology (SMT) has become the dominant method in modern electronics manufacturing, enabling higher component density, faster production, and improved reliability. Whether you're new to PCB SMT assembly or refining your production workflow, understanding the SMT assembly process is essential to achieve stable, high-quality results.

What Are the Main Steps in the SMT Assembly Process?

The PCB SMT assembly process typically includes the following core stages:

1. Solder Paste Printing

Solder paste is applied onto the PCB pads using a stencil.

Ensures precise paste volume and accurate deposition.

Quality at this step is directly linked to solder joint reliability.

2. Component Placement

High-speed pick-and-place machines place components (SMDs) onto the solder-pasted pads.

This stage determines accuracy, orientation, and consistency.

3. Pre-Reflow Inspection (Optional)

Some manufacturers use AOI or manual checks to confirm paste and placement accuracy before soldering.

4. Reflow Soldering

The board moves through a reflow oven, where:

• Solder paste melts

• Components bond to pads

• Controlled heating profile prevents defects like tombstoning or voids

5. Post-Reflow AOI Inspection

Automated Optical Inspection verifies solder joints, polarity, missing components, and short/opens.

6. Testing & Final Quality Check

Processes may include ICT, functional testing, and manual inspection, depending on task complexity.

SMT Assembly Process Flow Chart

Below is a simplified SMT assembly process flow you can integrate into your documentation:

This structure helps maintain consistency, quality, and traceability across your production line.

Where Can I Buy SMT Solder Paste for Assembly?

If you're looking for reliable, high-quality SMT solder paste, PCBGOGO is a trusted choice.

As a professional PCB & PCBA manufacturer, PCBGOGO provides stable, industry-tested solder paste suitable for prototyping and mass-production needs. The company also offers one-stop PCB SMT assembly services, allowing you to source materials and complete assembly in a single place for convenience and consistency.

If you’re already working with PCBGOGO for PCB manufacturing or assembly, you can easily place an online quote, and we can meet both small-batch and large-scale production.