The PPT will provide specific design inputs for Conduction cooled VPX system design

1. Understanding of
REDI
Kamal Raj Krishnan

2. AGENDA
 INTRODUCTION To REDI
 FORM FACTORS
 INTRODUCTION - Air Cool Design
 Design Considerations
 Important Rules to remember
 INTRODUCTION – Conduction Cool Design
 Design Considerations
 Important Rules to remember
 Any Questions..

3. INTRODUCTION - REDI
 REDI is the Mechanical specification of ruggedized electronics system
and it is defined by VITA48 Standard.
 REDI – Ruggedized Enhanced Design Implementation
 This REDI standard defines the mechanical design Implementation for
Plug in Units in VPX system Environment
 REDI defines Various Thermal Management Mechanical Design
implementations namely the Air Cooling, Conduction Cooling, Liquid
Cooling based on classified standards VITA 48.1, 48.2, 48.3..
 REDI defines two types of Plug In Units namely TYPE1 and TYPE2
 TYPE1 Plug-In Units are compatible for handling in 2 Level
Maintenance Environments where TYPE2 Plug-In Units requires
required precaution in handling
 Primary Difference between TYPE1 & TYPE2 units is the presence of
External covers
 REDI supports the 0.8”, 0.85” and 1.0” Pitch Plugging on Back Plane

4. REDI – FORM FACTORS
 REDI recommends two Board Sizes as 3U [100mm X 160mm] and 6U
[233.35mm X 160mm] for circuit Boards & plug-in units with AIR or
Conduction cool mechanism
 The base Mechanical specifications of PCB & Plug-In units are defined
by VITA46
 The Allowable Standoff Height for PMC/XMC is 10mm where 0.8” &
0.85” plug-in unit scheme. It is 12mm where 1.0” pitch Plug-in unit
scheme. In this Sufficient Package area to be planned for protective
cover for TYPE1 Card

5. REDI – Introduction to Air Cool Mechanism
 REDI Air cool mechanism defined by VITA48.1 standard specification
 For Conductive elements such as Frame Covers - Need not to connect to
PCB electrically except connecting to Safety Ground

6. REDI –Air Cool Mechanism
 This STD VITA48.1 defines Minimum PCB thickness as 0.06”
 It defines the mechanical interface specifications of components
namely Main PCB, Main Frame, PMC/XMC, PMC/XMC Cover, and
Secondary cover as it is indicated in the Image
 For main board Connector Protection, Primary Cover, PMC/XMC Cover
and Secondary cover can be extended up to connector Edge

7. REDI –Air Cool Mechanism
 Cover Thickness & extension specification is indicated in following
table
NF – Not Feasible, FwR-Feasible with Risk, F-Feasible

8. REDI –Air Cool Mechanism
 3U Air Cooled Plug-in Unit – Form factors

9. REDI –Air Cool Mechanism
 Primary side Cover provides following
 Accepts PMC/XMC and Cover for PMC/XMC
 EMC Compatibility & ESD Protection
 Maintains the managed Air flow paths in air-cooled applications
 Can contain Insertion / Extraction Features
 Secondary Side Cover provides following
 EMC Compatibility & ESD Protection
 Provides protection for secondary side components
 Maintains the managed Air flow paths in air-cooled applications

10. REDI –Air Cool Mechanism
 Secondary Side Cooling should be carefully evaluated particularly for
0.8” & 0.85” because of limited Gap between Secondary cover to PCB.
This is likely to be High Pressure Flow path where cooling air
requirements are high
 Component Layout can be critical to proper plug-in unit Cooling. The
Layout should consider the flow direction, shadowing effect, air
preheating, re-circulation etc..
 The Direction of Airflow should be as shown in image

11. REDI –Air Cool Mechanism – Important Rules to Remember
 Rule 7-4: Thickness of Plu-in unit that interface with sub Rack’s Card
Guide shall be 1.6mm +-0.2mm. But if Thicker PCB is recommended,
then the distance from Primary side of PCB to Outside of Secondary
cover is to be maintained as per Pitch of Plug-in units
 Rule 7-5: Covers shall be electrically connected to safety ground with
resistance not to exceed 100mohm
 Rule 7-9: Maximum Plug-in Width is defined by following Table
 Rule 7-11, 7-12: Primary & Secondary Side Cover is mandatory for
TYPE1 and it is not required for TYPE2 implementations
 Rule 13-1: In Order to achieve 2 Level maintenance, Type1 Plu-in units
shall comply with ESD requirements of VITA 47

12. REDI –Conduction Cool Mechanism
 REDI conduction Cool mechanism is defined by VITA 48.1
 It defines the detailed mechanical implementation for conduction cool
mechanism for PCB/Plug-In Units which is defined by VITA 46
 In Conduction Cooled System, there are two important components
namely Frame and Cover. Frame used to transfer the heat from
PCB/components to Sub rack and Cover is used to cover the Both side
of Plug-In units with support of ESD suppression
 Cover Plate differentiates the TYPE1 & TYPE2 Cards
 The PCB thickness can be variable from 0.06” [1.5mm] to
0.12”[3.048mm] and Even Thicker PCB also can be accommodated
based on considering the Guide Rail Thickness and so PCB is limited on
following
 For Primary Side Retainer design – 0.137”[3.48mm]MAX
 For secondary side Retainer Design – 0.112”[2.85mm]MAX

13. REDI –Conduction Cool Mechanism
 REDI conduction Cool mechanism defines 2 way implementation the Design based
on retainer placement.
 Primary Side Retainer
 Secondary side Retainer

14. REDI –Conduction Cool Mechanism
 REDI conduction Cool mechanism Supports Connector Side Protections
as it is indicated by image

15. REDI –Conduction Cool Mechanism
 REDI conduction Cool mechanism – Primary Side Retainer

16. REDI –Conduction Cool Mechanism
 REDI conduction Cool mechanism – Secondary Side Retainer

17. REDI –Conduction Cool Mechanism
 REDI conduction Cool mechanism – Retainer Position
 Plug-In Unit along with Retainer plugged on Guide Rail of Chassis with Gap of 13.34mm
 In Retainer Relaxed State, thermal interface side should not have any gap with Rack Wall and
Retainer side will have 0.76mm gap. Total Plug-in unit Thickness on Guide Rail is 12.57mm
 In Retainer tightened state, Total Plug-in Unit Thickness will be 13.3mm
 Card Guide Depth is 9.19mm to 10.41mm

18. REDI –Conduction Cool Mechanism – Guidance on Cooling
 Component Layout can be critical to proper plug-in unit cooling. The
layout should consider the how each component cooling, length and
cross sectional area of heat transfer paths etc..
 The conduction contact area for heat transfer from plug-in unit is
dependant on several factors, including the depth of card, the presence
of air cooled card guide projection.

19. REDI –Conduction Cool Mechanism – Important Rules to
Remember
 Rule 6-1: For Type1 Implementations, Both Primary & Secondary side
covers shall be required
 Rule 6-12: Covers shall be electrically connected to safety ground with
resistance not to exceed 100mohm
 Rule 6-11: Maximum Plug-in Width is defined by following Table
 Rule 7-11, 7-12: Primary & Secondary Side Cover is mandatory for
TYPE1 and it is not required for TYPE2 implementations
 Rule 13-1: In Order to achieve 2 Level maintenance, Type1 Plu-in units
shall comply with ESD requirements of VITA 47

20. REDI - VPX
 Any Questions for Discussion..........