... | material consisting of the base material impregnated with a synthetic resin such as epoxy or polyimide, partially cured to the B-stage. They are | MULTILAYER CIRCUITS ONLINE | molded under heat and pressure for multilayer printed circuitry and are used for bonding together the individual circuit layers of multilayer PCB's. Prepreg Verbundfolie, Klebefolie, | MULTILAYER CIRCUITS ONLINE | vorgehärtete Klebetafel. Prepregs sind harzimprägnierte Glasgewebe, bei denen das Harz teilausgehärtet (teilpolymerisiert = B-Stage). Diese Vorpolymerisierung ist gerade so hoch, daß die Prepregs bei Berührung | MULTILAYER CIRCUITS ONLINE | nicht kleben, jedoch das Harz bei höherer Temperatur und Druck wieder schmilzt und wieder aushärtet. In der Leiterplattenherstellung dient das Prepreg als Dielektrikum zwischen den | MULTILAYER CIRCUITS ONLINE | jeweiligen Kupferebenen und wird mit diesen durch den Preß- und Trockenvorgang verpreßt. | PROGRESSIVE DIE | A printed circuit that performs separate operations at each | MULTILAYER CIRCUITS ONLINE | station as material travels from one station to another. Progressive dies offer production of ...
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... the weight of the epoxyraisin of the Multilayer PCB`s rises 0,12 % due to the accumulation of moisture. If the capillary effect leads to | MULTILAYER CIRCUITS ONLINE | an increase of more than 0,17 % a gas pressure of 8-10 bar can be reached, causing delamination Even if delamination tests are made after | MULTILAYER CIRCUITS ONLINE | production, the danger of delamination can rise again due to unsafe transportation and long storage times. Therefore we would like to give you following proposals | MULTILAYER CIRCUITS ONLINE | to avoid the described problems: A.2 1 ) | STORAGE CONDITIONS PCB`S | should be stored in heated and dry rooms. Constant low humidity is | MULTILAYER CIRCUITS ONLINE | necessary before the soldering processes start. A rapid fall in temperature of more than 7 degrees causes condensation on the stored PCB`s. Humidity should never | MULTILAYER CIRCUITS ONLINE | exceed 65 %. The package must be kept intact although the polyethylene packages capability of keeping humidity away is not really reliable. A.3 2 ) | MULTILAYER CIRCUITS ONLINE | Storage time | THE STORAGE TIME OF PCB`S | should be as short as possible. PCB`s should be taken out due to ...
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... the Sn-3.5Ag-0.7Cu, Sn-4Ag-0.5Cu and Sn-3Ag- 0.5Cu systems which vary in use from continent to continent. However, the agreed expert opinion (IPC/Soldertech-Conference Brussels 2003) is | MULTILAYER CIRCUITS ONLINE | that the technological differences between the three systems are negligible. Sn-3.5Ag-0.7Cu is the most common alloy in Europe. SnCuNi Although there are even fewer field | MULTILAYER CIRCUITS ONLINE | results for the stabilised tin/copper system Sn-0.7Cu- 0.1Ni, it shows a lot of potential. It is called “stabilised” because the addition of nickel is said | MULTILAYER CIRCUITS ONLINE | to show an improved hardening reaction in soldering. The creation of needle-structured crystals is said to alter to rounder structures, achieving an improved soldering flow | MULTILAYER CIRCUITS ONLINE | for wave soldering of PCBs (reduction in torn soldering, less electrical bridging). This alloy was developed in Japan and is supplied in Germany by the | MULTILAYER CIRCUITS ONLINE | license holder, Balver Zinn. The Printed Circuit Board Manufacturer The SnCuNi system is particularly interesting for the PCB manufacturer as the ...
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