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Our portfolio is among the world's most extensive, with over 100,000 reliable connector products, including everything from electronic, electrical and fiber optic interconnects to switches and application tooling.
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There are many alternatives out there when it comes to choosing a crimp tool, and making the wrong choice can not only result in electrical inefficiency or wasted materials, but it could compromise your whole design. Crimp manufacturers recommend specific tools to achieve the best performance from their products, and here are some of the reasons why:
SAFETY: A UL specification signifies safety, security and reliability of an end-product, however, to comply with UL requirements often the manufacturer recommended tool and crimp in combination is required. Ultimately, the use of a generic tool could invalidate the UL specification of the end-product.
RELIABILITY: The manufacturer provides optimal performance data that is based on use of the appropriate tooling, therefore such specifications may not be achieved without the correct tooling. To ensure consistency and reliability it is always recommended to use the specified tool.
WASTED MATERIALS: Using the wrong tooling can result in multiple failed crimps, which leads to wastage as well as unreliable results.
WARRANTY INVALIDATION: Warranties and assurances of performance are often reliant on the recommended tooling being used, and failure to do so could compromise any warranties that are in place.
PEACE OF MIND: Specified manufacturer-recommended tooling can mean access to unmatched customer service and support to deliver not only the highest quality result, but also peace of mind that you have not compromised on the quality of the end-product.
Molex provides documentation and training resources, supported by their commitment to customer service, that helps to protect your investment in the correct tooling. Molex recommends and provides tools to produce optimal crimp terminations that provide reliable and robust electrical connections for every application.
The following video demonstrates how to make a proper crimp using hand crimp tools.
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The sample pack provided consisted of two male pins and three female sockets from their 200A connector range, which has a nominal 8mm diameter.
Both male pins are of a press fit design, with one already pressed into a connection plate and the other provided just as the pin, ready to be pressed into something like a busbar. Two of the female sockets have the floating design, one is a press fit and the other is surface mount. The final female socket does not have a floating mechanism and is also a surface mount fit.
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The sample pack only forms part of the 200A range, which appears to have the largest number of options. Unique to this range is a crimp connector and a plug and socket housing to provide an insulated connector. This item however, does not appear to have the floating design.
A cross section of the floating design, shows how the centre section is allowed to move within the outer connection, with the required pressure for the electrical conductivity, maintained by a ripple style washer on both sides of it (arrowed in the picture).
The Coeur CST system also include a 3.4mm diameter range rated to 75A and a 6.0mm range rated to 140A. These two ranges do not have as many items to them as the 200A range does. They do have a surface mount male pin, that does not appear to be present in the 200A range. Like the 200A range, the 140A range also has a screw fit male pin, but this is not included in the 75A range. All three ranges are rated up to 600V.
I am not sure why each of the ranges has different options, some of it may be down to machining limitations. However, this did seem a little strange to me, as I could utilise some of the options in the 200A range in the lower current ranges. The connectors appear to have been developed for use with the Triton busbar system also available from Molex, and this may also been a reason for the different options available.
Prices for the components in the UK seems to range from £2.00 to £3.50 for the pins, £4.00 to £7.00 for a socket without float and £7.00 up to £14.00 for a socket with float. These are prices for individual items and more competitive pricers were available for bulk orders.
The quality of the sample that arrived seems to be high. The male pins and female housings are coated in a silver-nickel plating. The contact springs within the female housings are gold-nickel plated. The washer in the float mechanism is also of the same gold-nickel plating, but these are not visible without cutting open the connector.
Inspection under a microscope did reveal a score in one of the male pins toward the tip, so I do not believe that it would be detrimental to the reliability of the connector.
As the connectors are mated and un-mated, a scoring pattern starts to appear on the male pins and particles of the plating appear on the female leaf springs as seen below.
The manufacturer's specifications give the number of mating cycles as greater than two hundred, so this connector is not meant for every day use. Neither is it intended to break the load current, the load would need to be switched out before unplugging these connectors. In contrast a standard IEC 60320 C13 connector (below) will have a minimum of 3000 mechanical mating cycles.
Comparison to other floating designs.
My knowledge of floating connector designs is basically from removable switchgear cassettes and fuse switches that employ a connector system to allow a section of the apparatus to be removed for either maintenance or isolation purposes. These designs tend to be a three piece design employing a floating spring loaded section between two connection bosses that are attached to the busbar and apparatus. Some are circular in design as seen on the left and others offer a connection between two flat bosses as seen on the right.
Other designs employ an over large tension spring to take up slack between the cassette mechanism and its housing, as shown for the 400V motor feeder cassette below.
A similar design is employed within fuse-switch isolators. Below is the base plate removed from the isolator, with the floating contact connected to the base plate contact on the bottom and the moving fuse carrier contact at the top. It can be seen that the floating contact needs to be connected to both contacts to make it stable.
These designs allow for thermal expansion and contraction of the copper conductors created by the cycling of the loads. As with the Molex CST connectors whilst they can be opened when live, they do not have the ability to break any significant current, so the cassettes have interlocking mechanisms that prevent them from being removed whilst the main isolator is switched on.
These designs differ significantly from the design offered by Molex. The Molex connector is a much more compact design, it would seem to be more robust than some of the existing designs Have utilised, that can become bent and damaged through too much mis-alignment. Failure of the spring also renders the contact useless, where as the Molex design offers physical protection for the wafer spring providing the float.
The downside for me with this type of application is that the housing are subject to type approval to IEC standards, so the use of connectors for this application is very much in the hands of well established manufacturers.
Smaller versions of the connectors provided could look useful for applications such as my current amplifier, that has swappable coils. The ad hoc nature of the build means that misalignment of connectors is quite likely, as depicted below. Whilst the black socket is aligned with the pin on the coil, a little misalignment can be seen between the red socket and the other pin of the coil.
The screw type pin could be made to fit very easily on the coil formers and replace the existing 4mm pins. Mounting the sockets onto the amplifier would be a little more challenging. The socket first has to be mounted into an electrical conductor to allow connection into the circuit, this in turn would need mounting into an insulator to stop it shorting to the other connector and / or the chassis. Not insurmountable, but is likely to get messy.
The Molex website contains dimensional drawings for each of the contacts so the necessary engineering tolerances can be established for mounting the press fit connectors. They also have a useful application document for the range that goes through installing the press fit and surface mount connectors, I have attached to this blog.
For the press fit a 0.02mm tolerance is recommended on the hole size as seen below. This, I imagine, would be quite taxing to manufacture without quality engineering cutters and machines.
The surface mount versions are recommended to be soldered within a reflow oven using solder paste as per below. Again, probably something outside of your average maker.
All the documentation is available from the Molex website on the link below, an then selecting the desired connector.
It doesn't really seem to be beneficial to attempt the above project, so in order to make some use of the connectors, I plan to make up a rig to test the mating cycle. I propose a linear actuator with a load cell at one end, so that the mating force can be measured. I cannot quite fathom out how to make the rig to also measure the un-mating force, unless I use two load cells. I then propose to measure the connector resistance each mating cycle using the 4-wire method.
This does seem like a good project to use the DAQ970A in a control environment, to operate the linear actuator, record the force and then measure the resistance, before un-mating the connector using the linear actuator. To do this will require a DAQM903A actuator card, that is a little difficult to get hold of in the UK, with out paying an elevated price. However, it will take me some time to get the connectors mounted into a connection system. If I can make the connection system strong enough, I should also be able to inject 100A through the connector and look at the thermal pattern, before and after the tests.
This is going to take me a while to source all the parts I need and carry out the manufacturer of the frame for the actuator and the connector, but over a period of time, it seems like a more achievable option.
The following video shows the resistance of the connectors being tested with a source measurement unit.
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The Molex Coeur CST, seems to be a novel approach to managing alignment of connectors, that can undoubtedly put strain on connections and lead to premature failure. They come in a number of different options, that is also dependent upon their rating, and a cost that restricts them to more specialist applications.
As well as allowing for movement during the connection process, they will also allow for movement through thermal expansion and contraction, which will certainly occur at the 200A rating of the connector.
Whilst they are a high quality connector, their use would seem to be more inline with commercial manufacturing, or a very serious maker with enough time and knowhow to install them correctly.
As global healthcare needs soar, demand is on the rise for mobile monitoring, therapeutic, and diagnostic devices. Medical devices have gone from bulky to portable to handheld to the latest wearable technologies for health conscious consumers. Manufacturers are sellingtoincreasingly tech-savvy clinicians and patients accustomed to using a myriad of portable and handheld electronic devices in their daily lives. Devices such as smart phones have set high consumer expectations for powerful features in small form factor medical devices.
Incredible shrinking medical devices require circuitry within tight space and weight parameters, and fast heat dissipation with increased airflow. Anybody who ever packed a suitcase or organized a cluttered closet knows firsthand that the ability of contents to bend or flex is essential to maximizing space and efficiency. Among a number of proventechnologies migratingfrom consumer electronics into medical devices, flex circuits and flexible printed circuit connectors can help designers optimize space in tightly packaged medical devices.
Occupying three dimensions, flexible printed circuits can be bent around packaging and even folded over to fit in a much smaller device enclosure. There are a number of other distinct advantages. Flexible substrates with single, double-sided, and multi-layered circuitry are ideal for high performance signal and power connections at an economical applied cost. Flex products can also be mounted in through-hole, surface mount and press-fit configurations.
Molex flex circuits give the designer greater flexibility and make electronic interconnection simpler and more reliable. Unlike hard board containing woven glass fibers that tend to result in signal loss, the materials, such as polyimide, used in flex circuits maintain signal integrity. Polyimide dissipates heat quickly, so flex does not require cooling from both sides. The flex materials closely match thermal expansion rates, which make it more reliable in hot and cold temperature extremes and temperature fluctuations in mobile healthcare applications.
Device miniaturization using flex circuit technology does require adaptations in production for tighter copper flex spacing and trace width. A precise develop-etch-strip process is required to etch circuits without removing too much copper. Incorporating blind and buried vias can help retain flexibility in designs requiring multiple layers on a flex circuit. Product handling requires extra care to prevent damage to circuit traces.
Using the right materials and manufacturing processes, Molex copper flex delivers sturdy circuitry with high speed capability, impedance control and minimal signal loss for a robust finished medical device. Ultra-reliable flex circuits are excellent for small, lightweight designs with complex high density circuitry. Significantly thinner and lighter than a traditional circuit board, flex makes any product naturally lighter, which contributes to overall cost savings and, in some cases, improved patient mobility and comfort.
Medical connectors can be divided into two broad groups based on how they are retained by the devices to which they are connected: locking – also referred to as latching – and non-locking. Each offers advantages and disadvantages and design and manufacturing challenges.
Locking and Non-Locking Connectors
USB connectors are examples of non-locking connectors
Example of “MS” – mil-spec type connector commonly used in early medical devices
Early medical cable assemblies used connectors adopted from military and industrial applications. These “MS” (mil-spec) metal connectors had knurled threaded couplers. Once screwed down to the receptacle, this connector would not come loose inadvertently. While this type of connection met the requirement that the cable not be disconnected unintentionally, they were difficult for clinical users to connect and disconnect and provided no safety disconnect feature which is often desirable for medical applications.
Custom overmolding of RJ connector helps prevent the latch mechanism from breaking off
The Registered Jack Connector
An example of a locking connector used in medical devices is the Registered Jack, or more commonly called the “RJ” connector. While some RJ plugs are rated for up to 1,000 mating cycles, the latch is typically exposed and easily broken. Once the latch breaks, the plug is poorly retained by the receptacle and the cable requires replacement.
One solution to improve the service life of an RJ connector is to overmold the body and include a flexible hood. The hood should allow the latch to be depressed but should also prevent the latch from being bent upwards and breaking off.
Locking Connector with Safety Disconnect
It is often desirable for a medical cable assembly, particularly those that connect between a patient and a stationary device, to lock to avoid unintended disconnection. In some instances, it is equally desirable for the connector to safely disconnect if axial force is applied to the cable such as when it is caught in a moving bed.
A safety release has been designed into the plug (red feature) which will allow safe disconnection above a pre-established load
This design requires that a minimum retention force be established for the locked connector over which the plug will disconnect. By carefully designing the locking mechanism, the connector will be held securely in the connected condition until the specified axial force is applied. Above that load, the connector will disconnect without causing harm to the patient, device or cable assembly.
Medical cables require a positive connection between the plug and receptacle. Any looseness in the connection may cause intermittent contact, resulting in unwanted noise or poor signal quality which may make diagnosis or therapy difficult, if not impossible.
How firmly the plug is held by the receptacle is referred to as retention force and is a controllable characteristic. Pin and socket selection, as well as the physical design of the plug and receptacle, allow control over both insertion and retention force. If the connector is expected to have a high number of mate and un-mate cycles, it is generally desirable to achieve retention force from the friction between metallic pins and sockets rather than plastic parts that wear more easily.
Connector Retention Force
The interface and friction between pins and mating sockets plays a large role in the retention force of a mated connector
Retention force of a connector pair – plug and receptacle – is nominally made up of the sum of the retention force of each pin and socket as well as any friction between the plug and the receptacle. For connector pairs with few contacts, friction, whether intended or unintended, between the insulator and receptacle wall may be the largest factor in determining the total retention force. For units with a larger number of contacts, little or no friction may be needed between insulator and receptacle wall.
An additional factor to be considered is that in a connector with more than a few contacts, the total retention force is greater than the sum of each pin to socket retention force. This characteristic is detailed in a paper by Robert S. Mroczkowski, Sc.D “The Mating Game” in “Connector Specifier” magazine, December, 2001. In the article Mroczkowski states that “mating force will always be greater than that value (if all contacts mate at the same time) because of tolerance and housing interaction effects.”
Enhancing Connector Retention Force
If the retention force achieved by pin-to-socket and friction of the connector housing is insufficient, one method to effectively increase retention force is to design the connector so that axial force applied to the cable does is not directly applied to the removal-axis of the connector.
Custom, non-locking connector can be disconnected by axial force applied to the cable
Custom, non-locking right-angel version resists disconnection when axial force is applied to the cable
Retention Force Specification
For non-locking connectors, one of the specifications established early in the project is the retention force of the plug to receptacle. The amount of retention force as well the required number of mate and un-mate cycles are factors considered in contact selection and part design.
Once mating and retention forces are established and documented, molds are designed in a “tool safe” manner. Tooling is designed to produce plastic parts that have retention force below the desired level. By removing metal from the tool, the connector becomes larger and retention force is increased. Done in very small increments, this method allows retention force to be “dialed in.” Sharing mold trial parts the design team allows insertion and retention force to be evaluated and adjusted before production parts are manufactured.
Connector Retention Force Testing
Once production parts have been manufactured, verification testing will confirm that all specifications, including connector retention force, are met. For non-locking connectors, Design Verification Testing will typically include measuring retention force at pre-established intervals during mate and un-mate cycle testing. This will confirm that retention force is maintained over the design life of the connector.
Engineering technician, Eric Yamane, performs Mate/Un-mate cycle testing by hand to more closely simulate actual use
David Moreno measures retention force at pre-defined intervals of mate/un-mate testing
Choosing to use a locking or non-locking connector for a medical cable assembly is a decision that should be made early in the life of the project and should consider the user and also how the cable may be used.
The Affinity engineering team has decades of experience designing both locking and non-locking medical connectors and the associated cable assemblies. Let us partner with you on your cable or connector project.
For additional information, contact your local Molex Sales Engineer or Account Manager or call us at +1 949.477.9495 or email us at firstname.lastname@example.org.
About the author
Business Development Manager - Affinity Medical - In his 30-year career in the medical industry, Hank has been exposed to almost every facet of the business, from marketing and manufacturing to new-product development, sales, and strategic management.
The IEEE MTT International Microwave Symposium (IMS) is the premier annual international meeting for technologists involved in all aspects of microwave theory and practice. For Molex, another outstanding IMS presence is to be expected as we showcase our broad range of products and solutions available for the RF/microwave marketat our booth #508 this year. Molex subject matter experts will showcase and display a range of innovative and reliable Molex interconnect products, covering frequencies up to 65 GHz. Such as:
The online RF Assembly Builder, a free configuration tool that simplifies the design process, allowing users to build a complete cable and connector assembly and instantly submit an RFQ without downloading any application or software. Molex RF connector designs can accommodate standard RG braided cables, micro coaxial cable, semi-rigid cable, vendor specific custom cables, LMR types and hand conformable cables.
Molex Customized RF/Microwave Connectors are tailored to specific applications and provide design flexibility to OEMs across a wide range of markets. Typical connector solutions include multi-port RF products, IP rated, sealed RF products, solderless PCB attachment, board-to-board solutions, non-magnetic connectors, and a wide range of cable assemblies and unique adapters, all available in 50 or 75 Ohm impedance.
The RF DIN 1.0/2.3 Modular Backplane System is an innovative system that enables designers to consolidate space and improve system routing of RF signals for board-to-board communications. The high-performance system delivers port expansion capability up to 10 ports and 75 Ohm impedance, with 1.00mm axial tolerance for superior orthogonal mating flexibility in a wide range of video and broadcast applications.
A wide range of standard, off-the-shelf, Molex high performance cable assemblies using Temp-Flex low-loss and ultra-low loss cables are now available. Stop by our booth for a free datasheet.
We look forward to another successful show and gaining additional insight on the market!
Molex Inc. will be exhibiting at the Electrical Wire Processing Technology Expo on May 14th and 15th at the Wisconsin Center in Milwaukee, Wisconsin. We will be teamed up with one of our core distribution partners, Heilind. We have been exhibiting at this show with Heilind for over 10 years.
Our focus at this show is to promote overall quality; quality material, quality processes, and quality equipment. When there is a quality issue, it becomes costly to all involved so we at Molex do our best to prevent quality issues before they happen in the field.
We offer a free crimp quality hand book for open and closed terminals. The reference document will show what a good and bad termination looks like and provide insight on what to look for and how to improve your quality process. This document comes in 15 different languages for both terminal types and we also offer a quality wall poster free of charge in 15 languages.
Below is an overview on a few tools we will be demonstrating at this show along with many more tooling options. Please stop by and visit our booth to get your free quality information sent to you.
The 63801-7200 (120V AC version), the 63801-7300 (240V AC version) TM-3000 Universal Press and the 63801-7600 (240V AC version) TM-4000 Universal Press are economical, high quality, electrically-operated, single-cycle and split cycle direct drive presses. They are designed to provide an effective method of applying a wide range of side-feed and rear-feed terminals to a pre-stripped discrete wire or cable. Both the TM-3000 and the TM-4000 are suited to mid-volume semi-automatic operations. Production flexibility is obtained using interchangeable FineAdjust or Mini-Mac applicators and most Industry Standard Applicators. These presses will complete one crimping cycle with each depression of the foot pedal and two depressions for split cycle. Safe operation is provided by an interlock switch that renders the press inoperative if the safety guard is opened or removed. These presses also have a secondary interlock switch in the back of the motor where the hand cycle wrench is used to prevent the foot switch from cycling during hand cycling operations or if the hand cycle wrench is accidently left in the motor. These cost effective industry standard crimp presses lower our customer’s capital equipment investments. The TM-3000 presses have a crimp range from 8awg and smaller; the TM-4000 press can crimp from 2awg un-insulated and 4awg insulated and smaller due to its large force capability. Both presses are “CE” certified and meet O.S.H.A. safety standards.
Utilizes both FineAdjust and Mini-Mac applicators side and rear feed, and most industry standard applicators
Press is set to 135.80mm (5.346”) Industry shut height
Ideal for mid-volume, semi-automatic applications
Meets O.S.H.A. safety standards is ANSI-Z535.2-2002 compliant
Totally enclosed for operator safety, including a power interlock switch for the front guard
Resettable counter for accurate batch counting
Modular solid state controls with an easy plug in power cord and foot switch.
The crimp force monitor measures the force signature of a crimped terminal and compares it to a reference crimp. Depending on the limits programmed, the measurements will show the termination quality to pass, fail, or be suspect. When a measurement is suspect, the display backlight will turn yellow to warn the operator. A failed measurement will cause the backlight to turn red and an audible alarm to sound. The operator must press a button to silence the alarm and reset the monitor. If connected, the crimp force monitor can inhibit the press foot switch when a failure occurs. The crimp force monitor can be set to display peak force in pound, kilograms, or newton units. A production counter is also included as well as job storage. This measurement tool allows for accurate discrimination of crimp defects from normal production and has a simple operator function which is easy to set-up.
Graphics color changes for visual indication of crimp defect
Audible alarm when defect is found
Press can be inhibited when defect is found
USB2.0 interface for PC software
Password protected set up
Mounts directly on the TM-3000 and TM-4000 presses
What are the most important drivers and developments in the today’s global electronics industry? Molex’s Brian Krause gave us an overview of what’s happening and what we should keep our eyes on for the future:
1. Personal Electronic Devices
Global economic development, rising Internet traffic, and the rapid proliferation of mobile devices are among key societal trends driving industry growth. The proliferation of the personal electronic device has driven tremendous design innovation during the past decade, as is the current consumer demand for smaller, more powerful devices with an unending amount of functionality. Data consumption continues pushing demand for ever-faster download speeds and storage capacity. The convergence of proven technologies developed for consumer electronics, infotech, and telecommunications into feature-rich mobile consumer, automotive, and medical devices has forged new market opportunities. Device functionality and content are burgeoning in automotive infotainment and safety systems, medical devices, and factory robotics and automation for industrial applications.
2. Immediate Access to Content
Technological advances and product convergence have brought to market mobile devices that offer broad-based functionality to empower people to better manage their daily lives. Smartphones have gone far beyond revolutionizing communications, impacting cultural norms and the way people access news, entertainment, photography, navigation, and even how we interact with our homes, vehicles, and, increasingly, automated equipment in our workplaces. Mobile devices have become indispensable. Consumers’ wish to access content anywhere, anytime, and on any device, also drove changes in the industry including more powerful and faster connectors to support the heavy bandwidth requirements of video and music streaming. OEMs also required a new way to address heat dissipation, creating new solutions for thermal management for a variety of electronic device connectors, ranging in size from microminiature to large scale. Sustaining the “smaller, faster, more economical” pipeline comes with significant design challenges.
3. Data Taxing Infrastructure
Globally, we are seeing many existing infrastructures — telecommunications, wireless networks — taxed by unprecedented growth in mobile communications. This mean we are in need of equipment upgrades and capacity additions. Demand is on the rise for data storage capacity and high-speed retrieval. High-density micro-miniature technologies that were originally developed for consumer product applications are expanding into markets such as infotech and mobile devices, leading to smaller devices and even greater mobility. Addressing next-generation, high-speed applications is a shared priority among many in the industry. Molex has taken action in meeting demand for miniaturization, higher data rates, and lower power consumption by partnering with other industry technology leaders to become a founding member of the CDFP consortium, whose objective is the development of a robust form factor for delivering 400Gb/s transceivers. The joint efforts of the CDFP consortium will increase customer choice, reduce end-user costs, and ensure interoperability to allow the copper cable and fiber optics transceiver market to expand.
4. Advanced Vehicle Innovations
The automotive industry has seen burgeoning in-vehicle content driven by customer demand for advanced product features, convenience, and connectivity. This applies not only to mobile device use but also to the proliferation of infotainment, telematics, and safety systems. The concept of the driverless car has also received considerable attention with the publicity surrounding the Google X R&D. While Google projects a rollout in 2018, some car manufacturers are expected to step up as early as 2015. Cadillac plans vehicles featuring “super cruise”, with autonomous steering, braking, and lane guidance. Nissan expects to sell vehicles with autonomous steering, braking, lane guidance, throttling, gear-shifting, and, as permitted by law, unoccupied self-parking. The capital, enthusiasm, and technologies exist, so we can expect to see further development of autonomous vehicles.
5. Next-Gen Hands-Free Electronics
The rapid proliferation of smartphones and tablets vividly illustrates the way innovative manufacturers can create entirely new markets — and have broad-reaching impact on how we as a society work, play, access news and entertainment, and communicate. We can expect to see portable and wearable electronics continue to gain momentum. Wearable markets, including smart watches, smart glasses, smart clothing, and even upscale smart jewelry, are projected to become a multi-billion dollar market. Wearable offerings are proliferating, with many new products in the prototype phase. These will usher in a new era of “hands-free” mobility. From a design standpoint, wearable devices present complex challenges to meet the signal and power requirements of a feature-rich environment, but also provide a compact, lightweight, and durable product, with a pleasing aesthetic that people will want to wear. Consumer expectations for wearable devices are strikingly similar to those in emerging telehealth and remote healthcare monitoring applications for wirelessly conveying data to hospitals and doctors in real time. Whether a user wants to schedule business appointments; track nutrition and fitness goals; safeguard their children, home, and pets; or monitor their heart rate or blood sugar, they want comfort, convenience, and less-bulky devices, with the ability to synchronize or communicate seamlessly with their smartphone or tablet via Wi-Fi, USB, Bluetooth, and other common communication protocols.
The 3FF micro-SIM card (UICC) is the 3rdgeneration SIM (Subscriber Identification Module) card since this form of card first appeared twenty years ago. It has dimensions of 12mm x 15mm x 0.76mm and the card has the same contact arrangement as its predecessors, i.e. the standard (credit-card size) and mini-SIM (25mm x 15mm) cards. The micro-SIM is backward compatible with larger SIM holders and SIM readers (via additional plastic cut-out surrounds).
Since the micro-SIM was developed specifically for the purpose of fitting into devices otherwise too small for a mini-SIM card, there is clearly a lot of pressure on connector makers to minimize footprint and height of micro-SIM sockets. In this blog I’d like to briefly analyze some of the factors contributing to connector height.I will focus only on sockets that fully envelop the card within the connector itself, (e.g. Guide & Holder, Push-Pull, Push-Push and Hinged type). Also I will not speak of PCB “mid-mount” designs, which would clearly allow further height advantage gains.
Micro-SIM connectors grip the card between a top cover and the main body of the connector, i.e. the plastic housing which contains the contacts. Allow me to start my analysis of connector height from the top down.
1) The top cover, usually a metal shell, may be reduced to 0.1mm and still retain the stiffness needed for overall structural rigidity. Of course, material selection is important and careful design will then be needed to ensure the shell is well-connected to the body of the connector and can take the stresses and strains of card mis-insertion and other tests. Going thinner than 0.1mm with conventional metals seems to run too high a risk, not just for connector strength, but also in terms of manufacturing and indeed metal strip supply. Tolerances on a 0.1mm strip are typically 0.005 to 0.010mm.
2) The 0.76mm (nominal) card thickness is clearly a given and the mouth of the connector cannot be much narrower than 0.90mm (nominal) to allow it accept the maximum thickness cards. Anything less will inevitably lead to card insertion difficulties as theSIM card, (unlike themicroSDcard) has no lead-in chamfer to aid card insertion.
3) The main body of the connector for ultra-low-profile designs is invariably an overmolded structure to help minimize the dimensional stack. The area of the connector and the other features the design attempts to incorporate will determine this thickness. Super high-flowing LCP (Liquid Crystal Polymer) materials can be used to create extremely thin walls, in places close to 0.10mm. However, some thicker sections are needed to maintain material flow and also to provide space for features to attach the shell and to hold the contacts in place. With contact material typically at 0.10mm (to obtain reliable forces over these tiny deflections) this means that a total thickness below 0.30mm is hard to achieve for the main body of the connector. Thinner is possible, but it will result in trade-offs in other areas of the design, possibly in efforts to meet a tight coplanarity specification. Orientation of contact beams and position of contact tip at full deflection will also determine how much of the PCB area beneath the connector can be used for circuitry.
4) Finally, many customers like to see a stand-off between the main connector body and the solder tails to improve solderability. This can typically be up to 0.05mm but is often specified at a min. of 0.0mm to at least ensure that no part of the connector body is below the level of the solder tails.
Adding the key dimensions in the stack above shows that 1.35mm nominal height (0.10 + 0.90 + 0.30 + 0.05) is typically as low as one can go with these designs. Of course, designers can play with 20 or 30 microns, particularly in the main body of the connector or in the stand-off area, but it will not significantly change the height. When overall tolerances are taken into account, we typically reach maximum socket heights of 1.40 to 1.50mm, similar to some ultra-low-profile microSD sockets on the market today.
Based in Eindhoven, The Netherlands, Colm is Group Leader for the European Satellite Team of Molex’s Micro Product Division. He has 15 years experience in the connector industry and has held a number of Engineering and Marketing roles both in Europe and in Japan. The focus of the Eindhoven team is to provide fine-pitch micro connector solutions to European customers.