Electronics Manufacturing Technical Articles

Nondestructive Inspection of Underfill Layers Stacked up in Ceramics-Organics-Ceramics Packages with Scanning Acoustic Tomography (SAT)

Jun 15, 2017 | Justin Zeng, Francoise Sarrazin, Jie Lian, Ph.D., Zhen (Jane) Feng, Ph.D., Lea Su, Dennis Willie, David Geiger - Flex International Inc., Masafumi Takada, Natsuki Sugaya - Hitachi Power Solutions, George Tint, Ph.D. - HDI Solutions

Ceramics packages are being used in the electronics industry to operate the devices in harsh environments. In this paper we report a study on acoustic imaging technology for nondestructively inspecting underfill layers connecting organic interposers sandwiched between two ceramics substrates.

First, we inspected the samples with transmission mode of scanning acoustic tomography (SAT) system, an inspection routine usually employed in assembly lines because of its simpler interpretation criteria: flawed region blocks the acoustic wave and appears darker. In this multilayer sample, this approach does not offer the crucial information at which layer of underfill has flaws. To resolve this issue, we use C-Mode Scanning in reflection mode to image layer by layer utilizing ultrasound frequencies from 15MHz to 120MHz. Although the sample is thick and contains at least 5 internal material interfaces, we are able to identify defective underfill layer interfaces....

Publisher: Flex (Flextronics International)

When to Use Flex Circuit vs. Rigid Circuit Boards

Jun 14, 2017 | Tuan Tran

Flexible circuitry may be preferable to rigid circuitry in situations where space or weight is limited....

Publisher: Power Design Services

Intermetallic Growth in Tin-Rich Solders

Jun 13, 2017 | Louis Zakraysek

For tin-rich solder alloys, 200 C (392 F) is an extreme temperature. Intermetallic growth in tin-copper systems is known to occur and is believed to bear a direct relationship to failure mechanisms. This study of morphological changes with time at elevated temperatures was made to determine growth rates of tin-copper intermetallics. Preferred growth directions, rates of thickening, and notable changes in morphology were observed.

Each of four tin-base alloys was flowed on copper and exposed to temperatures between 100 C and 200 C for time periods of up to 32 days. Metallographic sections were taken and the intermetallics were examined. Intermetallic layer thickening is characterized by several distinct stages. The initial growth of side plates is extremely rapid and exaggerated. This is followed by retrogression (spheroidization) of the elongated peaks and by general thick-...

Publisher: General Electric

Establishing a Precision Stencil Printing Process for Miniaturized Electronics Assembly

Jun 13, 2017 | Chris Anglin

The advent of miniaturized electronics for mobile phones and other portable devices has required the assembly of smaller and smaller components. Currently 01005 passives and 0.3 mm CSPs are some of the components that must be assembled to enable these portable electronic devices. It is widely accepted that about 65% of all end of the line defects occur in the stencil printing process. Given all of the above, it is critical that a precision stencil printing process be developed to support miniaturized electronic assembly.

This paper is a summary of a significant amount of experimental data and process optimization techniques that were employed to establish a precision SMT printing process....

Publisher: Indium Corporation

Low-Cost Inkjet Printing Technology for the Rapid Prototyping of Transducers

Jun 08, 2017 | Bruno Ando, Salvatore Baglio, Vincenzo Marletta, Antonio Pistorio; DIEEI-University of Catania, Adi R. Bulsara, Teresa Emery; Space and Naval Warfare Systems Center Pacific

Recently, there has been an upsurge in efforts dedicated to developing low-cost flexible electronics by exploiting innovative materials and direct printing technologies. This interest is motivated by the need for low-cost mass-production, shapeable, and disposable devices, and the rapid prototyping of electronics and sensors. This review, following a short overview of main printing processes, reports examples of the development of flexible transducers through low-cost inkjet printing technology....

Publisher: DIEEI-University of Catania

Evaluating the Effects of Plasma Treatment prior to Conformal Coating on Electronic Assemblies to Enhance Conformity of Coverage

Jun 01, 2017 | John D. Vanderford, Ann E. Paxton - Desich SMART Center, Dave Selestak - Nordson MARCH

The corrosion of Nickel-Palladium-Gold (Ni-Pd-Au) finish terminals in humid environments is known to be reduced with the application of a conformal coating such as acrylic. Corrosion has a higher rate of occurrence around the terminal ‘knee’ of a surface mount component, which may be reduced with the application of conformal coatings. Although radio frequency (RF) plasma processing is generally known to enhance conformity of conformal coating to surfaces through ionic bombardment, the effect on the functionality of assembled printed circuit boards (PCB) is not as well known.

The purpose of this study is to assess whether RF plasma processing can enhance the adhesive and coverage qualities of an acrylic conformal coating on PCBs, specifically on Ni-Pd-Au terminals with a knee, and if plasma processing has an effect on the electrical functionality of components and fully assembled PCB....

Publisher: MARCH Products | Nordson Electronics Solutions

Improve Assembly Turnaround For Tab-Routed Array Panelization

May 31, 2017 | Tuan Tran

These guidelines give the assembly team a standardized, no-nonsense method to produce a reliable panelization solution. By eliminating panelization guesswork, you ensure successful assembly even for complex projects....

Publisher: Power Design Services

Model for Improvement of Fluxing Process on Selective Soldering Machines

May 25, 2017 | Goran Tasevski, Elena Papazoska

Purpose of this research is to identify the factors that directly influence the effectiveness of the fluxing process in selective soldering machines, using the design of experiment methodology with associated factors and levels used in the experiment. Final findings gives directions for set up of the optimal fluxing parameters that will enable appropriate flux appliance and to gain reduction of soldering quality issues which foundations are from this process....

Publisher: Visteon Electronics

The First Reed Switch Auto Insertion Machine in the World hits the Market

May 21, 2017 | Denise Anderson-Rivas

Reed Switches, or Herkons, are extremely useful for many electronic applications. Reed Switches work by means of magnetism in reed relays and for electrical circuit control. In the presence of a magnetic field the reed will either open or close, depending on it's original positioning and purpose. They are extremely useful as they are hermetically sealed and can operate in almost any environment.

Reed Switch insertion into PCBs have historically been conducted by means of manual labor, by hand. As Auto Insertion mechanisms have advanced, there are new technologies on the market that can accommodate these highly useful switches via automated machines. Through Hole Technologies (THT) have advanced to now offer mechanized equipment to automate an assembly line that requires Reed Switch insertion. The first ever Reed Switch Machine is now available on the market for production assembly and auto insertion uses. This will make electronic products requiring Reed Switches easier to produce, faster, and more affordable for an entire manufacturing production. ...

Publisher: Shenzhen Southern Machinery Sales and Service Co., Ltd

How to Use the Right Flux for the Selective Soldering Application

May 17, 2017 | Bruno Tolla Ph.D, Denis Jean, Xiang Wei Ph.D

The selective soldering application requires a combination of performance attributes that traditional liquid fluxes designed for wave soldering applications cannot fulfill. First, the flux deposition on the board needs to be carefully controlled. Proper fine tuning of the flux physicochemical characteristics combined with a process optimization are mandatory to strike the right balance between solderability and reliability. However, localization of the flux residue through the drop jet process is not enough to guarantee the expected performance level. The flux needs to be designed to minimize the impact of unavoidable spreading and splashing events.

From this perspective a fundamental understanding of the relationships between formulation and reliability is critical. In this application, thermal history of the flux residues (from room temperature to solder liquidus) is a key performance driver. Finally, it is necessary to conduct statistically designed experiments on industrial selective soldering machines in order to map the relationships between flux characteristics and selective process friendliness....

Publisher: Kester