There are some great products utilized making flexible circuits, yet there is no product available today that could be called a panacea, having every positive quality and no disadvantages. This evaluation is based upon the fact that there are a number of various standards that are utilized to recognize and specify the preferable as well as crucial buildings of materials used to produce a flexible circuits laminate. This listing of preferable homes outlines a wide spectrum of demands and/or needs that may be put on a finished flexible circuits in an application. While no known product can attend to all the occasionally contradictory needs that the manufacturer and also customer may desire from a product, it is still of some value to have a mental picture of an optimal product as a way of bearing in mind what trade-offs may be required when choosing a suitable substratum for a product or application. With time hundreds of product mixes of movies, hinders and/or adhesives, in addition to processes and specialized tools, continue to be developed, supplying new opportunities to meet the expanding need for smaller, light- weight, greater rate wiring for devices requiring much less energy usage with more features and also capabilities. A cellular phone is one such device, in addition to parts of the facilities to sustain it.
A typical flexible circuit today is made up of a thin base dielectric polyimide (PI) film at a density of 50 to 125 microns in thickness (2 to 5 mils) with 1 to 3 oz. copper gage, with or without adhesive. Thinner gages are available, however flexible circuits with the measurements described are routinely made with great yield and good resistances, and also board/circuit makers have actually learnt how to take care of these products to additionally have sensible yields in high-volume atmospheres, particularly in automatic and semi-automated procedures.
A typical flexible circuit today is made up of a thin base dielectric polyimide (PI) film at a density of 50 to 125 microns in thickness (2 to 5 mils) with 1 to 3 oz. copper gage, with or without adhesive. Thinner gages are available, however flexible circuits with the measurements described are routinely made with great yield and good resistances, and also board/circuit makers have actually learnt how to take care of these products to additionally have sensible yields in high-volume atmospheres, particularly in automatic and semi-automated procedures.
DIMENSIONAL STABILITY
The flexible laminate needs to be dimensionally stable. Shrinkage or expansion of a flex circuit base product during processing is a concern for both manufacturer and also customer because it can impact both the fabrication of the circuit and its assembly. It is especially discouraging when dimensional change is not predicable.
The flexible laminate needs to be dimensionally stable. Shrinkage or expansion of a flex circuit base product during processing is a concern for both manufacturer and also customer because it can impact both the fabrication of the circuit and its assembly. It is especially discouraging when dimensional change is not predicable.
While products differ in their dimensional stability, there are a number of different means to deal with the results of dimensionally variable products, which will certainly be checked out in more detail in Practical Design Guidelines for Flex and also Flex Circuit Manufacturing Processes. Nonetheless, it is a definite advantage in manufacturing to stay clear of resorting to such practices. New film chemistries and processes have actually assisted in this area by allowing for the pattern of thinner products offerings. Examples of these brand-new PI films and buildings are defined later on in the chapter. The specifications that impact the dimensional security of base dielectric products, in order of importance, are:
1) Base movie kind and features associated with that chemistry
2) Process criteria used in manufacturing
If utilized), 3) Adhesive type(.
2) Process criteria used in manufacturing
If utilized), 3) Adhesive type(.
THERMAL RESISTANCE.
Due to the fact that many digital assemblers utilize raised temperature level processes such as reflow soldering for component assembly, the flex circuit product picked for usage in manufacture need to have the ability to dependably hold up against regular assembly procedure temperatures without distortion. With the well-meaning, yet uncalled-for as well as medically unadvised, mandated transfer to lead-free soldering in Europe, there will be added pressure to enhance thermal resistance efficiency. Lead-free solders have actually additionally restricted the selection of materials, compeling the individual to attend to the obstacle with either much more ex-spouse- absorbed materials or much more expensive low melting point solder when soldering is called for. This, along with policies concerning halogenated fire resistants, has actually caused several mate- rials to be reformulated or discontinued.
Due to the fact that many digital assemblers utilize raised temperature level processes such as reflow soldering for component assembly, the flex circuit product picked for usage in manufacture need to have the ability to dependably hold up against regular assembly procedure temperatures without distortion. With the well-meaning, yet uncalled-for as well as medically unadvised, mandated transfer to lead-free soldering in Europe, there will be added pressure to enhance thermal resistance efficiency. Lead-free solders have actually additionally restricted the selection of materials, compeling the individual to attend to the obstacle with either much more ex-spouse- absorbed materials or much more expensive low melting point solder when soldering is called for. This, along with policies concerning halogenated fire resistants, has actually caused several mate- rials to be reformulated or discontinued.
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