Reflow Soldering

Apparatus and Heat Transfer Processes

Balázs Illés, Oliver Krammer, Attila Geczy

• Publisher: Elsevier
• Year: 2020
• Print ISBN:
  9780128185056
• eBook ISBN:
  9780128185063
• Topic: Technology & Engineering
• Subtopic: Industrial Engineering
• Index: Technology & Engineering

Reflow Soldering: Apparatus and Heat Transfer Processes investigates the technology of reflow soldering from the aspect of the soldering ovens and apparatus. The authors begin by introducing the concept of surface mount technology. This is followed by three chapters exploring: Infrared ovens, convection ovens, Vapor Phase Soldering (VPS), and special reflow ovens. Each of these chapters includes a discussion of the physical background, structure and working principle, and characterization of the heating, flow and vapor parameters; and concludes with a review of the application of the techniques and typical solder failures. The book concludes with a discussion of the various numerical simulations of the different ovens. This book will be useful for researchers and process and quality and research and design engineers within the electronics and manufacturing industries. - Provides an overview and comparison of the existing reflow apparatus, heating methods, and working principles - Analyses and compares the different reflow ovens - Discusses useful tools such as characterization and measurement methods and includes numerical case studies to assist in solving soldering problems and improve soldering quality - Introduces Vapor Phase Soldering (VPS) technology

Chapter 1

Introduction to surface-mount technology

Abstract

In this chapter, the surface-mount technology and reflow soldering technology are overviewed. A brief introduction is presented into the type of electronic components, including through-hole and surface-mounted ones. Steps of reflow soldering technology are outlined, and details are given regarding the properties of solder material in this technology. The rheological behavior of solder pastes is detailed, and some recent advancements in addressing the thixotropic behavior of this material are summarized. The process of stencil printing is detailed next, which is the most crucial step in reflow soldering technology; since even 60%–70% of the soldering failures can be traced back to this process. The topic includes the structures of stencils, discussion of the primary process parameters, and process optimization possibilities by numerical modeling. Process issues of component placement are presented. The critical parameter (process and machines capability), which is used extensively for characterizing the placement process is studied. In connection with the measurement of process capability, the method of Gage R&R (repeatability and reproducibility) is detailed, including the estimation of respective variances. Process of the reflow soldering itself is detailed, including the two main phenomena taking place when the solder is in the molten state, namely, wetting of the liquid solder due to surface tension and intermetallic compound formation due to diffusion. Solder profile calculation and component movements during the soldering (e.g., self-alignment of passive components) are presented too. Lastly, the pin-in-paste technology (reflow solder of through-hole components) is detailed, including some recent advancements in the optimization of this technology by utilizing machine learning techniques.

Keywords

Surface-mount technology; reflow soldering; component skewing and self-alignment; stencil printing; numerical simulation; machine- and process capability; pin-in-paste technology

1.1 Electronic components

Today electronic circuits consist of almost solely surface-mounted components (~90%) and potentially only some through-hole components for realizing plug connectors or high power devices. Surface-mounted components and surface-mount technology are evolving since the mid-1960s [1]. Nowadays, the pitch dimensions reduced down to 0.3 mm or to even lower by the interest of portable device manufacturers, for example. Nevertheless, surface-mounted components never can supersede the through-hole devices entirely; therefore the assembly of both types of components should be done by the comprehensive soldering technology, which is reflow soldering.

The electronic components can be classified from many points of view, for example, they can be passive or active components or electromechanical components like switches, connectors, or relays. From the assembly point of view, the components can be through-hole (Fig. 1.1) or surface-mounted (Fig. 1.2). From the packaging point of view, they can be discrete components (one function is realized by one component—e.g., a resistor), they can be packaged as series of alike components (e.g., resistor array), or can be integrated components, in which many functions are realized by one component.

Figure 1.1 Through-hole integrated circuit—dual inline package (DIP). Reproduced with permission from G. Harsányi, Elektronikai Technológia és Anyagismeret, University lecture notes, BME-ETT, 2019, ISBN: 978-963-421-791-6 [2].

Figure 1.2 Scanning electron microscopy image of a surface-mounted resistor.

In this chapter, the different types of electronic components will be detailed. Classification possibilities will be elaborated for both through-hole and surface-mounted components. Finally, the advantages and disadvantages of both through-hole and surface-mount technology will be given and compared to each other.

1.1.1 Through-hole components

The through-hole (TH) component...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Chapter 1. Introduction to surface-mount technology
• Chapter 2. Infrared reflow soldering
• Chapter 3. Convection reflow ovens
• Chapter 4. Vapor-phase reflow soldering ovens
• Chapter 5. Special reflow techniques
• Chapter 6. Numerical simulation of reflow ovens
• Index