Short-Jumps - Three-dimensional Deformation
We are a bit proud since our Short jumper was our first connection part that we patented and thus the basis for additional patents which we hold. The initial idea was that with simple components we could offer cost effectively with the help of PCBs which can be threedimensionally formed.
We have succeeded, because due to the low price we can convert even the simplest, single sided PCB to a quasi „ rigid-flex circuit „. So that even low cost rigid PCBs gain a new attractiveness. Short -Jumps are always delivered on reels (8mm width) and thus can be automatically processed.
They consist of a copper, which results in a wide temperature range, and the current capacity is about 1 ampere, depending on ambient temperature.
Our Short-jumps are made of pure copper and are supplied with a surface of tin or lead free tin.
They are produced so that the bending can be carried out in a defined area, where different material thicknesses are formed. The dimensions correspond to the usual pitch dimensions which are used in PCBs.
Short-Jumps are produced from copper with a copper thickness of 250μm.
Thickness tolerance +/- 10%
Short jumps fulfil the task of producing an electrical connection. Simultaneously they are also stable enough mechanically to retain a permanent bend. This technology allows PCBs to be joined together in any angle, which in fact converts a standard assembly into a 3-D Circuit.
Short Jumps are not suited for repeated bending. Internal quality tests have shown that a material break takes place after about 10 bends at an angle of 90ar. Nevertheless under the assumption that an assembly is formed only once during construction, the bending loads are surely not critical weak points for the Short jumps.
We have carried out extensive bending tests to find out at which point the electrical connection of the Short- Jumps is endangered by mechanical overloading. The following pictures illustrate that after 10 extreme bends at 90 degrees the material becomes fragile and endangers the electrical connection.
Application of Short-Jumps
1: A PCB is first scored by the PCB manufacturer. Over the score line a Pick & Place machine assembles the Short jumps automatically on the SMD pads.
2: After the soldering (normally proceesed in the reflow oven) the PCB is broken at the score line:
3: 3: A mechanical and electrical connection is established through the Short-Jumps:
Current Carrying Capacity
- Test tension: 61.4 volts
- Test current: 0.417 amps
- Temperature range: -30°C +130°C
- Temperature cycle: 114 An
As indicated by measuring values a temperature change has no considerable influence on the conductibility. Therefore we conclude that the Short-Jumps are unconditionally applicable in a temperature range of -30°C to +130°C.
The rise of temperature of the Short-Jumps was measured relatively to the rise of current. The ambient temperature during this test added up to 22°C.
Tensile Strength Test
A determining factor for the mechanical stability and reliability of the connection between the PCB and Short-jump is the geometry of the SMD pads. To determine the optimum size we initiated a series of tests, which measured the tensile strength force of assorted sized pads. The table below illustrates a portion of the results of those tests.
Design Recommendations SMD-Pad
As a result we concluded that the optimum sizes for the SMD-pads are 1.6 mm x 1.2mm.
Solder Paste Stencil
To achieve good results during solder paste processing we recommend shrinking the stencil outbreaks by 0.05mm on the SMD pads on all Short-jump related locations while using a stencil sheet thickness of 150μm.
The PCB Design
As just shown, we were able with the help of tensile strength tests to find the optimum pad size for maximum stability of the connection between the Short-jump and PCB. The following image provides further advice for the construction of the PCB.
The Short-Jumps not only serve as electrical but also as mechanical components, it should be taken into account that a sufficient number of Short-Jumps are designed into the PCB to guarantee stability in the final state of assembly.
The number of Short-Jumps used, should be determined by PCB size, material thickness and the field of application.
Short-jumps can not only be placed above the score line but above a milling channel as well, which opens more possibilities in assembly bending.
Application as Coding Element
As a useful side effect the Short-Jumps can also be used to code hardware. In this case they serve only as classical Jumper to fulfil the function of a 0-Ω-resistor: