Technical Library | 2011-09-01 18:11:31.0
Scavenging, Site Dressing, Residual Solder Removal. What's in a name? "That which we call an onion, by any other name would smell as strong" (apologies to the immortal bard). And, regardless of the name you give it, the objective is the same, namely the clean up of remaining solder after a component (particularly a BGA) or R.F. Shield has been removed from a PCB. This paper will describe the various methods that are available and discuss their pros and cons.
Technical Library | 2021-11-17 18:53:50.0
The demand for product miniaturization, especially in the handheld device area, continues to challenge the board assembly industry. The desire to incorporate more functionality while making the product smaller continues to push board design to its limit. It is not uncommon to find boards with castle-like components right next to miniature components. This type of board poses a special challenge to the board assemblers as it requires a wide range of paste volume to satisfy both small and large components. One way to address the printing challenge is to use creative stencil design to meet the solder paste requirement for both large and small components. ... The most important attribute of a stencil is its release characteristic. In other words, how well the paste releases from the aperture. The paste release, in turn, depends on the surface characteristics of the aperture wall and stencil foil. The recent introduction of new technology, nano-coating for both stencil and squeegee blades, has drawn the attention of many researchers. As the name implies, nano-coated stencils and blades are made by a conventional method such as laser-cut or electroformed then coated with nano-functional material to alter the surface characteristics. This study will evaluate nano-coated stencils for passive component printing, including 01005.
Technical Library | 2010-10-21 16:01:17.0
Many component engineers are faced with a circuit requirement calling for resistors having voltage ratings well above that associated with surface mount chip resistors, but below the level of conventional high voltage resistors which are generally availab
Technical Library | 2013-04-12 07:31:31.0
As change is inevitable, therefore so is obsolescence. In the electronics sector, stocks of components used in subassemblies will eventually run out, no surprise there! However on many occasions, particularly in the often long product life cycles associated with the traditional UK OEM’s in the industrial, military and medical sectors, to name but three, component supply gets ‘difficult’ long before the customers products themselves reach their ‘end of life’. Component manufacturers work to a commercial agenda; when the popularity of a specific device wanes, or indeed when new features are demanded by the market, they will cease production and redeploy their manufacturing capacity to devices that are being demanded by their high volume customers; the global players.
Technical Library | 2010-04-15 22:06:32.0
As electronic products increase in functionality and complexity, there is an emphasis on affordability, miniaturization, and energy efficiency. The telecommunications, automotive, and commercial electronic markets are the leading drivers for these trends. These markets see high volume manufacturing with millions of units priced to the fraction of the cent. The choice of the packaging material for the electrical components for these markets can have a substantial effect on the cost of the final product. Therefore plastic encapsulated components are almost universally used in non-military applications over the conventional ceramic or metal electronic packages.
Technical Library | 2015-07-14 13:19:10.0
Bottom terminated components (BTC) are leadless components where terminations are protectively plated on the underside of the package. They are all slightly different and have different names, such as QFN (quad flat no lead), DFN (dual flat no lead), LGA (land grid array) and MLF (micro lead-frame. BTC assembly has increased rapidly in recent years. This type of package is attractive due to its low cost and good performance like improved signal speeds and enhanced thermal performance. However, bottom terminated components do not have any leads to absorb the stress and strain on the solder joints. It relies on the correct amount of solder deposited during the assembly process for having a good solder joint quality and reliable reliability. Voiding is typically seen on the BTC solder joint, especially on the thermal pad of the component. Voiding creates a major concern on BTC component’s solder joint reliability. There is no current industry standard on the voiding criteria for bottom terminated component. The impact of voiding on solder joint reliability and the impact of voiding on the heat transfer characteristics at BTC component are not well understood. This paper will present some data to address these concerns.
Technical Library | 2012-12-14 14:25:37.0
The popularity of low voltage technologies has grown significantly over the last decade as semiconductor device manufacturers have moved to satisfy market demands for more powerful products, smaller packaging, and longer battery life. By shrinking the size of the features they etch into semiconductor dice, IC manufacturers achieve lower costs, while improving speed and building in more functionality. However, this move toward smaller features has lead to lower breakdown voltages and increased opportunities for component overstress and false failures during in-circuit test.
Technical Library | 2013-08-07 21:52:15.0
PCB architectures have continued their steep trend toward greater complexities and higher component densities. For quality control managers and test technicians, the consequence is significant. Their ability to electrically test these products is compounded with each new generation. Probe access to high density boards loaded with micro BGAs using a conventional in-circuit (bed-of-nails) test system is greatly reduced. The challenges and complexity of creating a comprehensive functional test program have all but assured that functional test will not fill the widening gap. This explains why sales of automated-optical and automated X-ray inspection (AOI and AXI) equipment have dramatically risen...
Technical Library | 2013-10-03 16:05:39.0
Printed Circuit Board (PCB) is an essential component of almost all electrical and electronic equipments. The rapid growth of the use of such equipments has contributed enormously to the generation of large quantity of waste PCBs. The WPCBs not only contain valuable metals but also a large variety of hazardous materials. Conventional treatments of such WPCBs have their own limitations. By pyrolysis of WPCBs, it is not only possible to obtain the organic part of it as a fuel or useful chemical but can make further processing to recover metals much easier and efficient. In the present work, a kinetic study on the low temperature pyrolysis of WPCBs using a thermogravimetric analyser has been attempted...
Technical Library | 2021-08-25 16:34:37.0
As the traditional eutectic SnPb solder alloy has been outlawed, the electronic industry has almost completely transitioned to the lead-free solder alloys. The conventional SAC305 solder alloy used in lead-free electronic assembly has a high melting and processing temperature with a typical peak reflow temperature of 245ºC which is almost 30ºC higher than traditional eutectic SnPb reflow profile. Some of the drawbacks of this high melting and processing temperatures are yield loss due to component warpage which has an impact on solder joint formation like bridging, open defects, head on pillow.
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