Electronics Manufacturing Technical Articles

SMT Stencil, Surface Performance Returning to Basics in the SMT Screen Printing Process to Significantly Improve the Paste Deposition

Mar 15, 2018 | JimVillalvazo

The SMT assembly process is continuously challenged by the factors which enhance circuit board performance and limit productivity. The pick and place and reflow systems reflect these driven issues by adding more and more controls to their systems, but the fact is one of the age old processes continues to operate within the same rules since the dawn of the SMT assembly world: The SMT screen printing. (...)

This paper showcases a new stencil process that was discovered by reverting to the basics:understanding the reason for each stencil material process, focusing on detailed finishes and a disciplined aperture design process, maintaining original designs, and making the correctly designed apertures to control the paste deposition. The test results drove us to focus the efforts on the aperture walls In this paper we will demonstrate with lab tests SMT process results howthe improved paste release results in improved SMT print process performance and its positive impact on SPI yields and EOL performance....

Publisher: InterLatin

PCB Assembly With Obsolete Parts and Hard-To-Find Components

Mar 13, 2018 | Tuan Tran

Many companies take their supply chain for granted until they need an obsolete part or a hard-to-find component. Then the importance of having resourceful contract manufacturing partners becomes an incredibly valuable asset....

Publisher: Power Design Services

Optimization of Stencil Apertures to Compensate for Scooping During Printing

Mar 07, 2018 | Gabriel Briceno, Ph. D., Miguel Sepulveda

This study investigates the scooping effect during solder paste printing as a function of aperture width, aperture length and squeegee pressure. The percent of the theoretical volume deposited depends on the PWB topography. A typical bimodal percent volume distribution is attributed to poor release apertures and large apertures, where scooping takes place, yielding percent volumes <100%, while SMD apertures and apertures near PWB features that raise the stencil yield percent volumes >100%. This printing experiment is done with a concomitant validation of the printing process using standard 3D Solder Paste Inspection (SPI) equipment....

Publisher: Qual-Pro Corporation

Design and Process Development for the Assembly of 01005 Passive Components

Mar 05, 2018 | J. Li, S. Poranki, K. Srihari - Watson Institute for Systems Excellence, R. Gallardo, M. Abtew, R. Kinyanjui - Sanmina-SCI Corporation

Growing demands for smaller electronic assemblies has resulted in reduced sizes of passive components, requiring the introduction of newer components, such as the 01005 devices. Component miniaturization presents significant challenges to the traditional surface mount assembly process. A successful assembly solution for these 01005 devices should be repeatable and reproducible, and should include guidelines for (i) the selection of solder paste and (ii) appropriate stencil and substrate pad design, and should ensure strict process control standards....

Publisher: Sanmina-SCI

Stencil Design for Lead-Free SMT Assembly

Mar 05, 2018 | Chrys Shea

In order to comply with RoHS and WEEE directives, many circuit assemblers are transitioning some or all of their soldering processes from tin-lead to lead-free within the upcoming year. There are no drop-in replacement alloys for tin-lead solder, which is driving a fundamental technology change. This change is forcing manufacturers to take a closer look at everything associated with the assembly process: board and component materials, logistics and materials management, solder alloys and processing chemistries, and even soldering methods.

Do not expect a dramatic change in soldering behavior when moving to lead-free solders. The melting points of the alloys are higher, but at molten temperatures the different alloys show similar behaviors in a number of respects. Expect subtler changes, especially near the edges of a process window that is assumed based on tin-lead experience rather than defined through lead-free experimentation. These small changes, many of them yet to be identified and understood, will manifest themselves with lower assembly yields. The key to keeping yields up during the transition to lead-free is quickly learning what and where the subtle distinctions are, and tuning the process to accommodate them....

Publisher: Cookson Electronics

Troubleshooting SMT Solder Paste Problems

Mar 05, 2018 | Heraeus

Troubleshooting SMT Solder Paste Problems...

Publisher: Heraeus

Deposition of Solder Paste into High Density Cavity Assemblies

Feb 28, 2018 | Fernando Coma, Jeffrey Kennedy, Thilo Sack

Circuit functional density requirements continue to drive innovative approaches to high performance packaging. Some new approaches include; aggressive space reduction, embedded solutions, and those that offer some form of risk reduction and rework potential are now options that are being explored by customers. Requirements for assembly of these types of packages necessitate the deposition of solder paste and assembly of components into cavities of the substrates to gain z-axis density as well as area functional density. Advances in the fabrication of PWB’s with cavities using newly developed laser micro-fabrication processes along with increased circuit pitch density of 50 micron lines and spaces permit new applications for high performance electronic substrates.

First published at SMTA Pan Pacific Symposium...

Publisher: Celestica Corporation

Hand Soldering with Lead Free Alloys

Feb 22, 2018 | Metcal

As companies start to implement lead free soldering processes, hand soldering and associated techniques have been identified as key functions in the manufacturing process requiring additional research and development. Hand soldering tends to occur at the end of the process line where the circuit board has a high intrinsic value and so correct process control will have a significant affect on manufacturing costs and productivity.

This paper discusses the fundamental aspects of the hand soldering process and discusses process adaptation requirements for successful lead free implementation....

Publisher: Metcal

Making a Rigid Industry More Flexible

Feb 21, 2018 | Tuan Tran

Flex Circuits and Rigid-Flex Boards Are Taking Off...

Publisher: Power Design Services

What Makes Flex Circuit Assembly Different?

Feb 18, 2018 | Tuan Tran

Flex circuits allow manufacturers to be more creative than ever....

Publisher: Power Design Services