Micro parallel board connectors – Smaller, smarter and faster

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Precoplat Präzisions-Leiterplatten-Technik GmbH

In order to enable even more power between two parallel PCBs the Hybrid Power SlimStack has been developed by Molex. In particular, for connections to batteries with thermocouples or for remote USB (charging) interfaces, the Hybrid Power SlimStack allows a maximum current of 6 A on two parallel contacts. Based on a 0.4 mm grid, this product offers four signal contacts plus four power contacts each 3 A (alternatively two power contacts each 6 A) on a board area of only 2.5 mm x 4.2 mm at a mating height of 0.75 mm.

The Hybrid Power SlimStack as well has generous chamfers for blind mating. Of course, the double contact principle has been realized with the Hybrid Power SlimStack as well.

Whether SlimStack Armor (up to 3 A) or Hybrid Power SlimStack (up to 6 A): Both product families allow – additionally to signal transmission in the smallest possible package – to supply a mezzanine board with power or to dock a battery onto electronic boards, or connect the board by means of a flexible printed circuit boards to I/O interfaces.

All these details allow the designer of microelectronics whether in medical technology, in mobile applications for professional or consumer-electronics, in the field of Smart Watches, sensors or even in industrial electronics problem-free usage without process changes or the risk to pay a learning premium.

Further development of miniaturisation

How will miniaturization further develop? The MID (Molded Interconnect Devices) technology tracks are activated by laser on the plastic surface, which are then metallized with electroless plating whereby a three-dimensional design of the electronics is made possible with interconnect distances down to 0.5 mm. Also connector (with a few mating cycles) or pushbutton can be realized in this technique.

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Architectures for ease of manufacturing – an interview given by Herbert Endres, Molex.

Herbert, what were the challenges in developing the new SlimStack connectors?

Herbert Endres: The ends should be mechanically reinforced to avoid damages during blind mating. At the same time we wanted to achieve the function of previously purely mechanical soldering anchors and we also realized contacts for even higher current with these stamped and formed end pieces.

Which dimensions will be achieved for contact pitch, heights and numbers?

Herbert Endres: In the future, the contact pitch with two-row connectors will have their limit below 0.35 mm, since this is the smallest pitch for fine pitch soldering technique. The single-row connectors – eg. FFC connectors – can be realized down to 0.2 mm by using an alternating footprint in two rows each 0.4 mm to the board. The contacts in the connector will be also staggered to cope with the positioning tolerances.

The FFC cable assemblies have reached the technical manufacturing limit of 0.5 mm pitch. Just think about the sum tolerances of a 80-pin FFC cable with a width of only 40.5 mm. Molex recommends for these pitches gold plated cable ends and FFC connectors to prevent failures through possible whisker growth on tinned contact surfaces.

Will there be a paradigm shift in terms of connection technology with PCBs?

Herbert Endres: The rigid FR4 circuit board is still the most convenient option to interconnect electronics. Flexible printed circuit boards are used where space or connections into the third dimension are necessary. The combination of FR4 and flex board is always a question of the overall architecture of the electronic module. When there is no room for further development, we have to switch to customized MID solutions.

Which markets do you address with the new developments?

Herbert Endres: Microminiature connectors are increasingly used in the traditional markets as the consumer sector, in portable devices, in medicine, in the measurement and control technology, in military but also in the industrial electronics. These microminiatur solutions are increasingly used even in the telecom infrastructure segment due to the higher packing density, but also for reasons of cost.

Do you feel restlessly driven in the “connecting sector”?

Herbert Endres: We are monitoring the semiconductor industry; we discuss trends and identify the impact of new standards, chip packaging techniques and increasing data rates on the next generation of connectors. In the next steps, we are using electrical simulations and integrated CAD processes in order to start implementation. After this is complete we begin to work on the hardware, as we have to avoid unnecessary repetition. So you could say, that we are restlessly driven by ourselves.

However, the use of MID technology only makes sense when conventional two-dimensional printed circuit board technology will not support the functionality. The application of the solder paste must be carried out with a robotic dispenser.

The components must be placed with a 3D capable equipment onto the MID carrier and possibly fixed with adhesive. Tablets or jigs must be used to transport the assemblies through the IR oven during the reflow solder process.

On the other hand MID made parts are also suitable as pick & place solder able components if e.g. manufacturing is too costly in stamping technology. This includes in particular antennas. Molex has experience in design and tens of millions in manufacturing such antennas for mobile phones, which have to service up to 8 frequency bands simultaneously.

One standard product of these activities is the tiny 3 mm x 3 mm x 4 mm small 2.4 GHz WiFi antenna series 47948 which is easily soldered onto the circuit board using Pick & Place and IR reflow.

Thus, the MID technology helps to push further miniaturization of microelectronics, even with conventional printed circuit board technology.

* Herbert Endres at Molex he is responsible for technology and projects.

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Connection systems

Micro parallel board connectors – Smaller, smarter and faster

Further development of miniaturisation