Thursday, October 30, 2008

Pessimistic About Pessisim

After 20 years following the high tech economy I can say that the current economic situation will pass probably by the Spring of 2009. Auto and Home Appliance will be affected, but that is only 15% of the electronics buy. The concept of people not buying electronics is just not really going to happen, so don't worry too much. This tiome around the manufacturers will invest ,ore in research and developmemnt to avoid investments in marketable securities, so expect some really cool gadgets to come down the line. We are not all like Steve Jobs and the great team at Apple, we reflect more of Intel because what's good for Inetl is good fro passive electronics components.

Wednesday, October 1, 2008

New Joining Technology for Capacitors

A new method for mounting aluminum electrolytic capacitors to printed circuit boards may impact the entire passive component industry.

The joining of electronic components to a printed circuit board has historically required the heating and cooling of the same or different metals to create a mechanical and electrical bond. This process of soldering or brazing metals is fundamental in the manufacture of almost every electronic subassembly. The soldering process in electronics requires the application of a braze or solder between the designated surfaces of the respective components and heating the combined structure in a solder furnace or with a solder torch. And while this process has been used for decades to populate printed circuit boards with electronic components, the process creates a harsh environment for the components and the printed circuit board, which sometimes damages either the components, the board or both.

The traditional infrared reflow process and the wave soldering processes, or handheld torch heats both the component joint area and the component bodies being joined. The heating of the component body next to the joint area can slow the cooling down of the applied solder and can produce a solder attachment that can have an unusually enlarged microstructure which can lead to weakened mechanical and electrical properties. In passive electronic components the affect of excessive heat applied to certain types of dielectrics can lead to unique problems. One of the most sensitive passive components to heat is the surface mount aluminum electrolytic capacitor because of the internal requirement of a liquid electrolyte. When excessive heat is applied to an aluminum capacitor containing liquid electrolyte for an extended period of time, the electrolyte can boil and cause outgassing. This may not be immediately catastrophic for the component, but in some instances can lead to poor performance of the capacitor in a circuit, especially when applied as a filter for audio or video signals, or as an input or output filter on a power supply. Other passive components that have demonstrated difficulty in conventional soldering include DC film chip capacitors (because of the low melting point of such dielectrics as metallized polyester and polyethylene napthalate).

Reactive Foil Joining Technology:
Now a new process for mounting aluminum electrolytic capacitors and other passive components has been developed by Reactive NanoTechnologies, Inc. (RNT) of Hunt Valley, MD USA. According to the company- RNT’s patented NanoFoil® “is a new class of nano-engineered material, fabricated by vapor-depositing thousands of alternating nanoscale layers of aluminum and nickel.” When the reactive foil is activated by a 6 volt pulse of local energy, the foil reacts to precisely deliver localized heat up to temperatures of 1500°C in fractions (thousandths) of a second.

One of the most important developments of this technology is the ability to accurately predict the temperature profile on the various components when used in a joining application. The scientists at RNT have built a numerical model based on a simplified description of the self-propagating reaction of the foil. The model effectively simulates heat flow into the solder layers and temperature evolution over time within the bonded components. According to the patent, “bodies of materials are joined between mating surfaces by disposing reactive nanostructure foils between the mating surfaces and adjacent one or more layers of braze or solder. The composition and thickness of the foils are chosen, as by thermal modeling techniques, to minimize deleterious heating of the bodies and to provide an optimal heat profile to produce a nano-structured joint having superior mechanical properties.” This process can dramatically improve board yield ratios, especially when applied to parts that have demonstrated above normal failure rates because of direct access to applied heat for an extended period of time. In the instance of aluminum electrolytic capacitors for example, the applied heat lasts for only a fraction of a second, which significantly improvcs yields and ensures enhanced mechanical and electrical properties.

How The Technology Bonds Components To PCBs:
According to RNT, for joining components to a PCB, the multilayer foil is placed “between two metals that need to be bonded, along with two layers of solder or braze. Subsequently, mechanical pressure is applied to prevent the components from shifting during the RNT process and the chemical reaction between the aluminum and nickel layers in the foil is activated with a small electrical pulse” (that can delivered electrically, optically or thermally). The instantaneous heat from the foil's reaction “melts the solder or braze layers and enables metallic bonding at room temperature in less than one second.”

For joining applications the bonds created will experience lower stress and the materials being joined will not experience any damage because they are only heating the interface being joined. The average time that it takes for a reaction to start or components to join after activation of the foils is 10 milliseconds, or just 1/100th of a second. The bonding time is essentially instantaneous, and the entire device cools and can be handled within seconds. This limited application of heat to an aluminum electrolytic capacitor can theoretically eliminate failures or poor part performance that can occur with traditional IR reflow or wave soldering techniques.

Current Markets For The Reactive Foil:
Between 1994 (when the material was invented) and 2008 (when the current patent was granted- USP 7,361,412) the company has developed major markets in the joining of sputtering targets. The technology has also begun to make inroads into various types of electronic component assembly. The company’s primary customers in components are in surface mount LEDs and in plastic surface mount connectors. According to a spokesperson for the company- the first application of the reactive foil for joining aluminum electrolytic capacitors to printed circuit boards is already underway a large European manufacturer of automotive electronic subassemblies.

Aluminum Electrolytic and Other Passive Components:
The use of RNT’s foil for joining aluminum capacitors to the PCB is a new and exciting application for the company. The fact that neither the component nor the board area is exposed to excessive heat for an extended period of time through wave or IR reflow soldering improves the quality of the finished sub-assembly and dramatically reduces defects. Other passive components that may benefit from this new joining technology include plastic film chip capacitors (which have been known to delaminate during excessive soldering processes). DC film chip capacitors are usually manufactured from one of three primary dielectrics- PET, PEN and PPS. PET is usually the lowest cost dielectric used in plastic film chip capacitors, but it also has the lowest melting point, which makes it unsuitable for all phases of soldering. PEN is more resilient and resistant to the affects of excessive heat, but it is more expensive. PPS has the highest tolerance for heat, but is the most expensive plastic dielectric film because of its high heat tolerance. RTN notes that the reactive foil joining technology has not as of yet been applied to film chip capacitors, but suggests it is just a matter of time before it is tried.