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ABS Frequently Asked Questions

UHD Questions

  1. Ease of Assembly
  2. Backplane Shorting Protection
  3. EMI Protection
  4. Connector Weights
  5. Ease of Routability
  6. Different Module Thicknesses
  7. Multiple Source
  8. Ease of Repair
  9. Modularity
  10. Specifications
  11. Materials
  12. Stacking Connector
  13. Connector Misalignment
  14. Press-Fit
  15. Multi-Row
  16. Keying
  17. Make-First/Break Last
  18. Connector Pattern

1. Ease of Assembly

Describe the complete process of attaching connectors to the module and backplane. Describe any special tools, processes, or skills required.

How to Attach Module (Daughterboard) Connectors:

a. Slide the module onto the connector making sure not to damage the connector leads or any components in proximity to the connector leads or metal tiebar. The factory has preset the lead termination spacing (gap) according to customer module stack-up to allow positive pressure on the printed circuit board pads.
b. Adjust the module so that the heat sink mounting holes are aligned to the connector mounting holes.
c. Secure the module to the connector using the appropriate hardware, but only finger tight. Do not tighten at this time.
d. The module must now be moved to obtain the most accurate pad to lead alignment. This can be accomplished by moving the module and visually inspecting the pad to lead location under a microscope. Adjust the module until both sides of the printed circuit board pads are equally spaced in relation to the connector leads.
e. Now secure the module in place by torquing the screws.
f. Amphenol recommends using connector lead alignment tool part number 696-1109- 500 to obtain final alignment for soldering connectors with stamped metal leads. Amphenol has designed this tool to be used with the family of Ultra high Density connectors and various module widths. The tool provides alignment by locating a comb onto the metal tiebar tabs, raising the leads and moving the entire bay of leads until they are centered on the Printed circuit board pads. Soldering of the leads can be performed while the alignment comb holds the leads centered on the pads. Consult factory for details.
g. Solder the leads using hand soldering or hot bar soldering. Do not allow the solder to reflow into the score line as this will prevent separation of the leads during tie bar removal. Note: The plastic insulator are molded using Liquid Crystal polymer or Polyphenylene Sulfied and can withstand soldering operating temperatures.
h. Amphenol has designed a tiebar break off tool to provide a simple method for removing the tiebar. This hand tool material is titanium and has been designed to slide onto the Amphenol metal tie bar tabs. The tiebar can be removed by moving the tool back and forth until the leads separate at the score line. Consult factory for details and specific tool part numbers.
I. Repeat process for multiple bays and opposite side of module.
There are no special skills beyond understanding existing soldering methods and soldering inspection. The alignment tool does not require any special skills. Amphenol will provide the customer with an application document which contains the alignment tool sequence procedure, details and drawings.

How to Attach Backplane Connectors.

UHD backplane connectors comprise a two-piece construction comprising tuning fork contacts and insulator housings. The contacts are loaded from a carrier strip onto specially-designed loading blocks. The molded loading blocks assure proper contact height, gap dimension, and contact orientation. Amphenol typically manages the custom construction of all backplane assemblies using the UHD interconnect.

2. Backplane Shorting Protection

Describe how the backplane connector is designed to prevent potential shorting of contacts if a metal object (e.g., a tool) accidentally contacts the backplane connector.
Amphenol's UHD backplane connector is not prone to potential shorting of contacts. Two design provisions prevent a metal object, such as a hand tool, from shorting with the backplane contacts. First, the backplane insulator is made of non-conductive plastic. Second, because of the closed-entry feature of the backplane insulator, the contacts are not exposed beyond the insulator shell. The closed-entry feature of the insulator also protects the female contact from mismating and damage during mating of the Line-Replaceable Module (LRM) connector.

3. EMI Protection

Describe how the backplane connector design protects the module from EMI. In particular, how is the backplane connector shell attached to the backplane to prevent EMI leakage paths.
Although there are no specifications which directly address the EMI/RFI characteristics of the UHD backplane connector, the connector is isolated from outside EMI/RFI. The UHD design relies on the integrity of the shell-to-shell and the shell-to-earth-ground electrical connection.
Amphenol can provide an optional metallic shroud which encloses the backplane connector receptacle. This shroud interfaces with the backplane ground plane using compliant press-fit technology. This ensures a continuous ground plane from backplane to daughterboard. The conductive shell-to-shell DC bond provides local shielding for the connector and a conductive path to earth-ground.
Amphenol's extensive signal integrity experience shows that a ground plane should be at layer 2 and N-1. This agrees with the required grounding for EMI. Amphenol's experience has also shown that EMI and RFI management should be applied across the front and rear sides of the backplane in addition to the module connector.

4. Connector Weights

What is the weight of each half of the UHD connector? Also, list the weights of all other hardware (e.g. fasteners, support plates) needed to implement the connector in the system.
The table below lists connector weights.
Module Connector 372 signal pin SEM E Format 0.08 lb (36.28 g)
Module Connector 396 signal pin SEM E Format 0.08 lb (36.28 g)
Module Connector 556 signal pin SEM E Format 0.12 lb (54.43 g)
Backplane Connector 372 signal pin SEM E Format 0.06 lb. (27.21 g)
Backplane Connector 396 signal pin SEM E Format 0.06 lb. (27.21 g)
Backplane Connector 556 signal pin SEM E Format 0.06 lb. (27.21 g)

5. Ease of Routability

Assuming lines and spaces of 0.005", describe the optimal method of routing.
Amphenol's UHD connector is designed to maximize the efficiency of backplane signal trace routing. This is essential since inefficient routing can greatly affect the overall number of layers needed on the backplane and thus impact its overall complexity, weight and cost. The method for routing single-track lines through the connector is shown here. This is the direction that most bus lines would run on the backplane. As a system manufacturer of backplanes, Amphenol recognizes the need for efficient routing to maintain electrical characteristics while minimizing costs.

6. Different Module Thicknesses

Describe how the UHD connector is designed to accommodate various module thicknesses.
Amphenol's daughtercard module connectors with stamped metal contacts (the M1050 series) are adjusted at the factory to accommodate a variety of module thicknesses ranging from 0.090" to 0.360". This is easily accomplished by adjusting the formed dimension, not by using different contacts. Doing so only affects the height on the pad.
Amphenol's flex connector (the FM1050 series) can be used for applications such as air flow thru, crossovers and shielding.

7. Multiple Source

Is there currently another supplier who could supply the connector per industry standards?
Amphenol has no patents or proprietary position that would prevent any co-supplier from offering this miniature standard fork-and-blade design. There are multiple sources supplying this connector to the various industry standards: EIA, IEEE, and DESC.

8. Ease of Repair

At what level is the connector repairable?
UHD backplane connectors (KS1050 series) are easily repaired: The backpanel contains the tuning forks which are easily repaired in the same manner that the press-fit tuning forks in MIL-C-28859 and MIL-A-28870 are repaired. (see technical bulletin 2044)
The module connectors (M1050 and FM1050 series) are not field repairable.

9. Modularity

Describe the modularity of the connector.
UHD connectors incorporate 0.500-inch-long modules, each containing 40 signal pins. This represents the basic form-factor for building customized connector arrays. These segments can also be used as cavities for fiber-optic termini, power contacts or coaxial contacts. These interchangeable modules can be included anywhere along the connector, thus providing a high degree of design flexibility.
Due to the structural integrity afforded by bonding these individual insulator modules into the module connector frame, this design flexibility can only be exercised at the factory. This is especially important for optical or RF termini modules which may require through-holes in the backplane.
The backplane connector is not available as a one-piece construction. It is modular and consists of tuning forks, signal pin insulators, and polarizing bushings. It is also available with insulator housings for coax, fiber-optic, and power contacts. Amphenol has designed specialized tooling for installation of these connectors into the backplane and recommends that all backplane connectors be installed at the factory.
New designs are continually being proposed to customers utilizing the same basic 0.500-inch connector inserts in new machined metal bodies. This saves the customer the cost of retooling new contacts and bodies, and decreases delivery times substantially.

10. Specifications

Which military specifications was the connector designed to and what testing has been performed?
The UHD connector was developed to a Naval Avionics Center (NAC) statement-of-work and was later proposed for use in the JIAWG J87-2A specification. There are existing EIA, IEEE and DESC specifications which directly cover this connector.

11. Materials

What materials are used to manufacture these connectors and are they suitable for space environments?
A full list of UHD's materials and finishes is available. This connector is space qualified and has been designed in on several space applications, including the space shuttle and the Iridium satellite program.

12. Stacking Connector

Can the UHD Connector be adapted to provide a stacking connector?
The tail of the male blade flex contact has been modified for additional length, allowing it to be soldered into a 0.090" thick daughtercard (module). This allows the connector to be mated to the standard backplane, thus providing a stacking connector. The distance between the parallel boards is 0.5". This stacking connector can also be used for I/O connections (i.e. rigid flex).

13. Connector Misalignment

What are the limits for misalignment that the connector will compensate for?
The connector system is designed and tested to allow a 0.030" displacement. The guide pins and bushings will pick up the 0.030" displacement and correct the connector placement to allow the male blades to pick up the insulator which provides the final guidance.
Float is controlled by blade and closed entry feature. Blade is nominally .018" thick; closed entry feature is nominally 0.026" wide. Connector float is +/- 0.004" under all tolerance conditions.

14. Press-Fit

Why does Amphenol recommend and design press-fit, when other high-density designs use solder terminations? What are the advantages of press-fit?
Amphenol is a leader in backplane systems for avionics/space and defense/aerospace applications. We're experienced not only in the application of our own connector systems, but also with a wide range of competing interconnect systems, which we're often called upon to integrate into backplane assemblies for our customers. Many of these are of the press-fit style, although others are through-hole soldered. Amphenol is certified to solder per J-STD-0001, MIL-STD-2000A and several commercial specifications. As an assembler of backplanes, Amphenol understands the difficulties of soldering connectors to thick (> than 0.125") multilayer backplanes. Amphenol pioneered the press-fit concept to allow a freedom to the designer, and to minimize the cost of ownership through the life of the program.

a. Benefits of Press-Fit in Board Construction
1. No need for thermal relief pads.
2. Pad placement only where necessary.
3. Use of heavy copper inner layers.
4. No need for soldermask, except as a scratch-resistant coat.
5. Use of conformal coat, with minimal masking. The press-fit contact will pierce through Types UR & XY conformal coat (military approved).
6. The board size is not limited by the size of a solder wave or vapor phase machine.
7. The board becomes the contact retention area of the connector, reducing the overall height of the connector and allowing more circuit space. In addition, space is not necessary for solder standoffs and as a washout area.
8. The board aspect ratio is limited only by the board manufacturer, not the solder assembly.

b. Benefits of Press-Fit in Board Assembly
1. There is no delamination due to soldering temperatures or improper baking.
2. There is no warping due to stress relief of the inner layers.
3. There is no measeling of the board due to soldering temperatures.
4. Contacts are gang inserted, reducing assembly time.
5. No solder joints, so long-term reliability of the assembly is not negatively impacted by the thermal cycle.
6. With aspect ratios on the boards at 10 to 20 and total copper weights exceeding 30 ounces per square foot, it is almost impossible to solder these panels. The solder will not flow reliably up the holes before it freezes off, causing inadequate solder joints.

c. Cost of Ownership
This is the cost of a backplane assembly once it has left the production area. The press-fit contacts are individually replaceable. Every contact can be replaced up to three (3) times per MIL-A-28870. This replacement can be done in the field with simple tools and basic training.

15. Multi-Row

Is the connector available in any other configuration than the 8-row?
Yes. Amphenol has tooled the connector in both 4-row and 6-row configurations. Consult Amphenol for specific configuration.

16. Keying

What are the keying provisions?
UHD is currently tooled for the eight-sided NAFI keys ('D', 'V' round). A reduced-size key system has been developed, and it provides the same number of keying combinations as the standard NAFI keys. It has been shown that by using three NAFI keying positions, together with both the 'D' and 'V' keys, the JIAWG requirement of 4,000 keying combinations can be met.

17. Make-First/Break Last

Is there support for make-first, break-last pins?
The UHD connector currently has tooled two male blade contact lengths which can be used for make-first, break-last. In addition, there is an EMI shield which is designed to establish contact before the contact pins.

18. Connector Pattern

When laying out the backplane it is critical that the contact pattern be viewed from the correct side. UHD is based upon a staggered contact pattern; there IS a correct and an incorrect orientation. The plated-thru hole must be drilled with a .0295 (.75mm) drill and plated to .025±.002.

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