Technical Library | 2019-05-29 10:38:59.0
Decapsulation, or de-cap, is a failure analysis technique which involves the removal of material packaging from an integrated circuit (IC). After de-cap, visual inspection by optical microscopy of the internal circuitry may reveal areas where damage is most likely to have occurred. In addition, scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) can identify the composition of any anomalies present after de-cap under higher magnification. The removal process of package material can be done either mechanically or chemically depending on the design of the integrated circuit. With ceramic packaging, de-cap is usually done mechanically by chiseling off the top with a fine razor and small hammer. For plastic packaging, de-cap requires chemical etching by strong acids. In this Tech Tips article, de-cap by chemical etching will be outlined step by step.
Technical Library | 2019-05-30 10:59:13.0
In the current economic environment, the ability to reuse ball grid array(BGA) components that have failed due to solder defects may be an efficient way for electronics manufacturers to reduce costs. Cost may not be the only driving factor in the decision to engage in this recycling practice. The increasing demands placed upon the complexity of microprocessors and integrated circuits (ICs) has decreased the availability of some components, and increased their lead time. Because of this, reballing may provide a means to meet schedule, reduce rework turn-around time, and give a manufacturer a decisive advantage over other companies in an ever increasingly competitive market. This article will discuss the process of reballing BGA components (Figure 1), examining preparation (the preform method, the screen method), and cleaning and bake-out.
Technical Library | 2019-06-12 10:33:58.0
The success of ball grid array (BGA) placement on electronic assemblies is as much a matter of proper preparation and planning, as it is technique. In some designs, it is more appropriate to apply BGAs using a rework station that isolates the placement of the device, without subjecting the entire assembly to thermal reflow. This is especially beneficial in board constructions where the number of BGAs is limited, and the application of the solder paste is difficult, due to small pitch features that stretch the limitation of the stencil construction. Another application for rework stations, involves very large and thermally conductive BGAs, which will not uniformly reflow with other components on the assembly, and may require special process parameters for their proper placement. The most common use of BGA rework stations are for assemblies requiring BGA removal and replacements due to failures in the initial assembly stage.
Technical Library | 2019-06-19 11:06:46.0
Tin (Sn) metal displays the characteristic of growing “tin whiskers” from pure tin coatings (most actively on relatively thin, electrodeposited or immersion tin coatings), usually months or years from the initial deposition of the tin. Tin whiskers are electrically conductive, filamentary, single crystals of white (beta phase) tin. These filaments of single crystal tin are usually one to five microns in diameter, and a few microns up to several tens of millimeters long, that grow spontaneously from the tin coatings. Alloying additions of several percent (by weight) of lead (Pb) prevents these electrically conductive tin whiskers from growing. Pb alloyed into the Sn was discovered to prevent the occurrence of tin whiskers in electronic assemblies in the 1950s as the Bell Laboratories solution to the problem of tin whiskers. The alloying of the tin with lead has thus quietly averted incalculable losses from short circuits in electronic equipment for the last 60 years.
Technical Library | 2019-09-16 09:41:02.0
“What is Virtual Manufacturing?” The simplest answer is a manufacturing simulation using a computer. The more complete answer is that virtual manufacturing is the process of designing a model of a real system and conducting experiments with this model for the purpose of understanding the behavior of the system. In today’s complex manufacturing environment, processes must be completely understood before implementation in order to “get it right the first time.” To achieve this goal, the use of a virtual environment is essential for simulating individual manufacturing processes and the total manufacturing system. By driving compatibility between the product design and the assembly plant process, these virtual tools enable the early optimization of cost, quality, and time to help achieve integrated products, process and resource design, and affordability.
Technical Library | 2019-09-23 09:35:00.0
Failure analysis (FA), by its very nature, is needed only when things goawry. Before any testing is performed on the sample, a decision mustbe made as to whether or not the sample is allowed to be destroyedin the process of testing. Non-destructive testing can allow for re-use of the assembly since the functionality is not altered, but there still remains the possibility that inadvertent damage can occur through the course of the analysis. If non-destructive testing is preferred, then the following types of analysis can be performed. The testing can be divided into four categories: visual, X-ray (X-ray imaging and X-ray fluorescence), cleanliness (resistivity of solvent extract, ion chromatography, and Fourier transform infrared spectroscopy), and mechanical (non-destructive wire bond pull).
Technical Library | 2019-09-27 09:14:41.0
One of the most critical factors in preventing corrosion from occurring in electronics is maintaining the state of cleanliness. This is not an easy feat to achieve. Corrosion is defined as the deterioration of a material or its properties due to a reaction of that material with its chemical environment. [1] So, to prevent corrosion from occurring, either the material or the chemical environment must be adjusted. Adjusting the material usually means application of a protective coating or replacing a more reactive material with a less reactive material. Adjusting the chemical environment usually means removing ionic species through cleaning, and removing moisture, usually with a conformal coating or hermetic package. Ionic species and moisture are problematic because they form an electrolyte which is able to conduct ions and electricity. Any metal that comes into contact with the electrolyte can begin to corrode.
Technical Library | 2020-03-09 10:50:17.0
A customer called the Helpline seeking advice for cleaning no-clean fluxes prior to applying a conformal coating. The customer's assemblies were manufactured with a no-clean rosin based solder paste (ROL0) and were cleaned with an isopropyl alcohol (IPA) wash. After cleaning, a white residue was sometimes found in areas with high paste concentrations and was interfering with the adhesion of the conformal coating (Figure 1). For conformal coatings to adhere properly, the printed circuit board (PCB) surface must be clean of fluxes and other residues. In addition, ionic contamination left by flux residues can lead to corrosion and dendrite growth, two common causes of electronic opens and shorts. Other residues can lead to unwanted impedance and physical interference with moving parts.
Technical Library | 2020-04-01 14:24:56.0
It happens much too often; manufacturing engineers are brought into a NEW product design phase at the very end of a design and are asked to provide input that should have been provided much earlier. One needs to understand how the circuit board design and quality of the manufacturing process not only effects assembly yield and product reliability, but how it could also affect the results of any testing that is done to circuit packs during prototyping. It is important that any circuit pack (including prototypes) that will be used in reliability, performance and functional testing be designed with the proper features and assembled with a manufacturing process that has been developed to produce a high-quality assembly. If not, the results of any testing might not represent the actual characteristics of the design and provide miss-guidance to future changes.
Technical Library | 2020-05-08 18:22:31.0
A customer contacted the Helpline to perform analysis on a lead-free assembly which exhibited intermittent functionality. The lead-free assembly exhibiting intermittent functionality when pressure was applied to the ball grid array (BGA) packages. Industrial adaptation of a Restriction of Hazardous Substances (RoHS) compliant solder standard has created a new host of failure modes observed in lead-free assemblies. Pad cratering occurs when fractures propagate along the epoxy resin layer on the underside of the BGA connecting pads. While originating from process, design, and end use conditions, it is the combination of a rigid lead-free solder with inflexible printed circuit board (PCB) laminates that has advanced the prevalence of this condition. Pad cratering is simply the result of mechanical stress exceeding material limitations.
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