03. Surface Mount Technology
SMT process control from paste to inspection: print, place, reflow, verify.
Part 1. Solder Paste, Stencils & Printing (with in-line SPI)
Printing is not just "applying glue"; it is the foundation of quality in SMT assembly. Studies co...
1.1 Paste Chemistry & Alloy Choice
Solder paste is the single largest variable in the SMT process, responsible for over 65% of end-o...
1.2 Storage, Thawing, Handling, and Traceability
Solder paste is a time-sensitive chemical system, not a shelf-stable commodity. Its performance d...
1.3 Stencil Types, Thickness, and Lifecycle
The stencil is not a static plate; it is a precision tooling die that degrades with every print s...
1.4 Aperture Design Tactics
Do not default to a 1:1 match between the PCB copper pad and the stencil aperture. The copper pad...
1.5 Printer Setup, Cleaning, and Verification Checklist
The screen printer is not a "set and forget" machine; it is a dynamic system where variables drif...
1.6 SPI Metrics, Cp/Cpk, and Closed-Loop Rules
Solder Paste Inspection (SPI) is not just a "reject gate" to catch bad boards; it is a process co...
Part 2. Pick-and-Place & Conveyors (programs, feeders, line control)
The pick-and-place machine is the heartbeat of your SMT line—where speed must meet sub-micron acc...
2.1 Machine Architectures
Machine architecture defines the DNA of the Surface Mount Technology (SMT) line, establishing a f...
2.2 Program Creation & Tuning
A pick-and-place machine's performance is governed by the program that drives it. From the moment...
2.3 Feeders, Splicing & Replenishment
Feeder performance is the silent determinant of pick-and-place uptime. Even the fastest machine s...
2.4 Board Handling & Line Control
The flow of panels between SMT stations — handled by conveyors, buffers, and communication links ...
2.5 First Article & Golden Board
The First Article (FA) procedure is the mandatory process gate that confirms a product is ready f...
Part 3. Reflow Soldering (profiles, atmosphere, defects)
Reflow is the final thermal challenge where heat management dictates the reliability of every sol...
3.1 Heat Transfer & Zone Control
The reflow oven is the final, irreversible step in Surface Mount Technology (SMT), where the mech...
3.2 Profiling Methods
Profiling is a distinct step from zone control. While previous chapter addressed the physics of h...
3.3 Air vs Nitrogen
The atmosphere inside the reflow oven is a direct variable in solder joint formation and reliabil...
3.4 Alloy-Specific Nuances
Every solder alloy possesses a unique thermal and metallurgical signature that dictates its requi...
3.5 Defect Mechanisms & Fixes
Reflow soldering defects are the consequence of failed controls upstream: paste, stencil, placeme...
Part 4. In-Line Optical & X-Ray Inspection (SPI recap, AOI, AXI, SPC)
Inspection is the data engine that makes your SMT line predictable. This chapter covers the tools...
4.1 SPI Recap & Cp/Cpk
Solder Paste Inspection (SPI) transforms the stencil printing process from a manual art into a pr...
4.2 AOI Fundamentals
Automated Optical Inspection (AOI) systems function as the visual quality gate of the SMT line. U...
4.3 AXI Techniques
Automated X-ray Inspection (AXI) is a critical, non-destructive testing method that uses X-ray te...
4.4 Programming & Tuning
Inspection programming translates raw component and solder data into actionable pass/fail judgmen...
4.5 SPC & Dashboards
Statistical Process Control (SPC) is the operational discipline that converts raw machine data in...
Part 5. Electrical Test (ICT, FCT, boundary scan)
Testing is the financial and technical firewall that stops bad product from shipping. This chapte...
5.1 Strategy & Coverage
Electrical test is not an option; it is a financial and technical firewall. The goal of a well-de...
5.2 ICT & Fixture Design
In-Circuit Test (ICT) is the fastest, most effective way to eliminate 90% of all common structura...
5.3 Boundary Scan Essentials (JTAG)
Boundary Scan, formalized as IEEE 1149.1 (JTAG), is a mandatory technology for structural testing...
5.4 Functional Test Design
Functional Test (FCT) is the final stage of the electrical quality strategy, confirming that the ...
5.5 Data Logging & Repair Tickets
Data logging and the formal Repair Ticket system are the nervous system of modern electronics man...
Part 6. Changeover and Maintenance
Updated table of content
Part 1. Printing and SPI Control 1.1 Paste Chemistry and Alloy Choice Keeps the alloy/paste...