Smiths Connectors MHD/MDD/MDP CONNECTOR SERIES PCB High Density Connectors

Smiths Connectors MHD/MDD/MDP series high-density PCB connectors

In modern electronic systems, with the continuous improvement of functional integration, the demand for signal and power interconnection on PCBs (printed circuit boards) is becoming increasingly complex. High density, high reliability, and miniaturization have become the core challenges in connector design. Smiths Connectors, with its innovative Hyperbolic contact technology, has launched three series of high-density PCB connectors: MHD, MDD, and MDP, which are widely used in fields such as aerospace, military, industrial control, communication equipment, and medical electronics that require high reliability. This article is based on the original content of the official product catalog "MHD Catalog - (A4)", systematically organizing and deeply analyzing the technical characteristics, structural configuration, material selection, electrical performance, and application advantages of these three connectors, providing authoritative and professional technical references for engineering designers.

Hyperbolic Contact Technology: Core Advantages

The core technology foundation of the MHD, MDD, and MDP series is Smiths Connectors' proprietary Hypertec (Hyperbolic Contact) hyperboloid contact technology. This technology arranges the metal wires inside the contact sleeve in a hyperbolic trajectory to form an elastic wire contact structure around the pin. Compared with traditional leaf springs or point contact methods, the Hyperboloid structure has the following significant advantages:

1. Low insertion and extraction force

By precisely controlling the angle between the pin and the metal wire inside the sleeve, extremely low insertion and extraction resistance can be achieved. The metal wire is smoothly deflected during pin insertion, forming a linear contact that ensures contact pressure and reduces insertion and removal forces.

2. Ultra long contact life

The wiping action of the Hyperboloid structure is extremely gentle, greatly reducing mechanical wear on the contact surface. This series of connectors can support up to 100000 insertion and extraction cycles with almost no performance degradation, significantly better than traditional connectors.

3. Extremely low contact resistance

Due to the formation of multiple linear contact paths between the metal wire and the pin, the actual contact area is much larger than that of point or line contact designs. At the same time, the wiping action can continuously remove surface oxide layers or pollutants, keeping the contact interface clean. The measured signal contact resistance is ≤ 12 m Ω, and the power contact resistance is ≤ 2 m Ω, which is about half of the traditional design.

4. Higher current carrying capacity

The Hyperbolic structure can optimize current carrying capacity by adjusting the number, diameter, and angle of metal wires. The contact area is distributed on a larger surface, allowing the current carried by the unit metal wire to be safely doubled. The rated current of the signal contact is 3A, and the power contact can reach 15A.

5. Impact and vibration resistance performance

The metal wire is lightweight and has low inertia, and can follow the displacement of the pin in real-time in impact or vibration environments, maintaining continuous contact. The contact area is evenly distributed 360 ° around the pin, and the three-dimensional symmetrical structure ensures uninterrupted electrical connection under any directional disturbance.

6. Applicability of high-density interconnect systems

Due to the lack of additional hardware to overcome insertion and extraction forces, the MHD/MDD/MDP series can significantly reduce the size and weight of subsystem designs, making it particularly suitable for high-density inter board interconnect applications.

MHD series: high-density modular connectors

2.1 Overview of Technical Characteristics

The MHD series is a flagship product for high-density PCB applications, supporting mixed configurations of signal, power, coaxial, and high-frequency contacts.

Materials and Coatings

Insulator: Diallyl phthalate (DAP), flame retardant grade UL94 V-0

Frame: Aluminum alloy

Contact: Copper alloy

Guiding element: brass+nickel or stainless steel

Contact coating: nickel base+gold surface

environmental performance

Working temperature range: -55 ° C to+125 ° C

Contact anti exit safety distance: static 2.0 mm, dynamic 1.80 mm

Standard insertion and extraction times: 5000 times

Pull out force of single contact: ≤ 0.5 N

Special contact: Compliant with NFC 93569 standard

Electrical performance

Contact resistance: signal ≤ 12 m Ω, power supply ≤ 2 m Ω

Rated current: signal 3A, power supply 15A

Insulation resistance:>10 ⁴ M Ω

Rated voltage: 200V

Voltage resistance: 800V

Signal contact diameter: 0.50 mm

Diameter of power contact: 2.00 mm

Coaxial impedance: 50 Ω

2.2 Ordering Code Rules

The MHD series adopts a five bit encoding structure:

Series: MHD

Layout: such as 052, 5HA, 100, 1HB, 200, etc

Components - Polarity - Coating:

1.5: Male plug, MIL coating

2.4: Female socket, MIL coating

1.9: Male plug, MIL tin plated

2.8: Female socket, MIL tin plated

Termination method:

10: 90 ° bend insertion, PCB thickness 1.60

30: Direct insertion, PCB thickness 2.40

44: SMT (non aligned), PCB thickness 3.80

96: Direct insertion, PCB thickness 4.50

Guidance method: refer to the guidance section for details

2.3 Module Configuration and Insertion Stage

The MHD series supports multiple single row or multi row module configurations, including 052, 5HA, 100, 1HB, 200 and other contact quantities. The product catalog provides a detailed "module configuration" view (Mating Side Views), showing the layout positions of signal and power contacts in the socket end view.

Standard plug-in stage

The maximum allowable radial offset during the process of plug and socket insertion is 0.15 mm (in all directions).

Multiple mounting examples are provided to guide engineers on how to achieve floating installation in a chassis or backplane to compensate for mechanical tolerances.

2.4 Detailed explanation of termination methods

The MHD series supports multiple termination styles to adapt to different PCB thicknesses and application scenarios:

Receptacle end

Through-hole soldering -90 °: reference number 10 (PCB 1.44-1.76mm, A=3.25+0.45, B ≤ 6mm); Reference number 11 (PCB 1.98-2.42mm)

Through hole welding - straight type: reference number 30 (PCB 2.16-2.64mm, A=3.5-4.0mm); Reference number 31 (PCB 2.88-5.50mm)

Surface mount technology (SMT): Reference number 41 (PCB 1.44-1.76mm, A ≤ 5.20mm); Reference number 42 (PCB 2.88-3.52mm); Reference number 43 (PCB 2.16-2.64mm); Reference number 44 (PCB 3.60-4.00mm); Reference number 45/47 (special thickness)

Plug end

Through-hole soldering -90 °: reference number 10 (PCB 1.44-1.76mm, A ≤ 5.95mm); Reference number 12 (PCB 2.88-3.52mm)

Through hole welding - straight type: reference number 30/31, size corresponds to socket end

Surface mount: Reference numbers 41-47, supports both center and non center PCBs

All termination methods provide an "Unbuild up of tolerances" diagram to help designers plan PCB pads and apertures reasonably.

2.5 External dimensions of connectors

The product catalog provides complete external dimension drawings from 52 core to 200 core, including:

View mating side of plug and socket

Theoretical dimensions annotation

The configuration of the terminal side contact should refer to the details of the board preparation

For example, the external dimension drawing of a 200 core socket clearly indicates the 2XA size, flange installation hole position, and guide part position, which facilitates mechanical structure design.

2.6 Guiding device

The MHD series provides multiple guidance methods to ensure that the plug and socket are correctly aligned in blind insertion or high-density environments:

Polarization mother guide (vertical installation): length 5.50 mm, single set mass 0.65g (P/N: 121122, etc.)

Polarized male guide (installed vertically or horizontally): such as P/N: 110111

Non polarized guiding element: such as P/N: 125126

Fully polarized guiding element: such as P/N: 130131133134

Special guide for power supply or high current contact: P/N: 190191

The guide element can be mixed with the contact element for installation, and some models can have a single set weight of up to 1.50g (such as P/N: 124), providing stronger centering force.

2.7 Board Preparation Details

For configurations with different numbers of contacts (052, 5HA, 100, 1HB, 200), the catalog provides detailed drilling layouts, including:

Direct termination: the position, diameter, and pad size of the through-hole between the socket and the plug

90 ° termination: through-hole offset and solder mask design for bent insertion structure

Surface mount end connections: SMT pad shape, spacing, and steel mesh opening recommendations

Important reminder: For non-standard module configurations, please contact the technical department for exclusive drilling layouts. But the typical layout provided by the directory can be used by engineers for preliminary mixed configuration design.

2.8 Power Supply and High Frequency Contact Parts

The MHD series supports special contacts that comply with the NFC 93569 standard, suitable for power and high-frequency signal transmission.

Power Contacts

90 ° End Connection: Male P/N 020 085 1-10R OG, Female P/N 020 084 2-10R G1

Straight end connection: Male P/N 020 087 1-30R OG, Female P/N 020 056 2-30R G1

Welding cup end connection: Male P/N 020 091 1-40R OG, Female P/N 020 060 2-40R G1

High Frequency Contacts

Supports multiple coaxial cables and installation methods:

Vertical installation, compatible with flexible cable Ø 1.9mm (RG 178 B/U or RG 196): KMX 3-M 081/KMX 3-F 081

Horizontal installation, compatible with flexible cables Ø 1.9mm: KMX 3-M 092/KMX 3-F 092 (compatible with motherboard thickness ≤ 3.2mm)

Vertical/horizontal installation, compatible with flexible cable Ø 2.5mm (RG 316): KMX 3-M 101/112 and corresponding female head

Vertical/horizontal installation, compatible with semi-rigid cable Ø 2.2mm (RG 405): KMX 3-M 131/142

Straight/90 °/SMT termination for direct PCB installation: KMX 3-M 041/032/172

Extraction tool

P/N: SD-03000CX003: Used for disassembling high-frequency or power contacts.

MDD series: Dual density modular connector

The MDD series has a similar structure to MHD, but focuses more on a dual density layout, which means achieving a higher density of signal contacts within the same housing size. Its technical characteristics, materials, environment, and electrical parameters are basically the same as MHD, with the main differences reflected in:

3.1 Module Configuration

The MDD series provides a view of the socket mating surface, showcasing dual or even multiple rows of micro contact layouts. Typical configurations include 100 core, 200 core, etc.

3.2 Termination method

Same termination code system as MHD series:

Used for through-hole welding on 10/11/30/31/96, etc

44 grade for SMT

3.3 Guiding device

The MDD series guide component models are highly compatible with MHD, including:

Public polarization vertical installation: 111

Mother polarization vertical installation: 121122

Mother non polarized vertical installation: 126

Mother full polarization vertical/horizontal: 130133

Power supply/high current guidance: 190 (female, vertical), 191 (male, horizontal)

3.4 Board Preparation Details

The MDD series also provides drilling layout diagrams for 100 and 200 cores, emphasizing the correspondence between the contact positions of straight, 90 °, and SMT end connections and the PCB aperture.

MDP series: dedicated high-density connectors

The MDP series is positioned as a dedicated high-density connector, suitable for applications that require extremely high contact density and have strict space constraints. Its technical characteristics are consistent with MHD/MDD, but emphasize more on:

4.1 Simplified ordering code

The MDP series only offers a 200 core configuration, with MDP as the coding series and a fixed layout of 200. The component polarity only supports 1.9 (male, MIL tin plated) and 2.8 (female, MIL tin plated), and the termination methods include 10/31/44/96. The guiding methods include 114 (male non polarized vertical), 125 (male non polarized horizontal), 122 (female polarized vertical), and 134 (female polarized horizontal).

4.2 Dimensions and Guidance

The MDP series provides external dimension drawings of plugs and sockets, clearly indicating:

The socket end can be paired with a male non polarized guide (such as 125)

The plug end can be paired with a female polarization guide (such as 122)

Surface mount end connections adopt non aligned PCB design (reference number 44)

4.3 Board preparation details

The catalog provides a complete drilling layout diagram of 200 core MDP, including the position matrix of the contact pieces under the straight end connection and surface mount end connection.

Product Line Overview and Application Suggestions

Smiths Connectors has built a complete product matrix covering standard high-density, ultimate dual density, and dedicated high-density applications through three major series: MHD, MDD, and MDP. All series are based on Hyperbolic hyperboloid contact technology, ensuring long-term reliability under high insertion and extraction times, strong vibration impact, wide temperature range, and strict electrical requirements.

5.1 Selection Suggestions

MHD series: Suitable for complex systems that require mixed configuration of signals, power supplies, coaxial or high-frequency contacts, such as military aviation electronic equipment, radar systems, and base station backboards.

MDD series: suitable for pure signal or low-power applications with extremely high PCB area requirements, such as portable testing equipment and high-density acquisition cards.

MDP series: suitable for standardized 200 core high-density interconnects, such as aerospace computer modules and internal stacking of medical imaging systems.

5.2 Design Considerations

When preparing the board, it is necessary to refer to the drilling layout diagram corresponding to the number of contacts, especially when mixing configurations, it is necessary to contact the technical department for accurate layout.

The selection of guide components should consider the insertion and removal direction (vertical/horizontal), polarization requirements, and whether a dedicated guide for power/high-frequency contacts is needed.

For applications that require more than 5000 insertions and removals, Hyperboloid technology can still support higher numbers, but it is recommended to consult the original factory life curve.

When assembling high-frequency contacts, attention should be paid to the length of cable stripping and the matching of crimping tools.

5.3 Other Smiths Connectors product lines

In addition to MHD/MDD/MDP, Smiths Connectors also offers:

Modular/rectangular connector: supports mixed signal, power, coaxial, fiber optic, and pneumatic modules.

Circular connector: M12/M23/M40/M58, metal/plastic casing, push-pull locking.

Spring probe connector: Z-axis compliant, high lifespan, suitable for board testing and blind insertion.

Fiber optic connector: ARINC 801 standard, extended beam and floating fiber optic terminal.

Filter connector: EMI/RFI filter, transient protection, RoHS compatible.