Differences

This shows you the differences between two versions of the page.

--- ice:pcb_mechanics [2014/06/30 18:49] – [PCB Stackup] jtshugrue
+++ ice:pcb_mechanics [2021/08/26 15:26] (current) – external edit 127.0.0.1
@@ Line 2: / Line 2: @@
 This page presents the mechanical specifications for PCB's in the ICE Platform when being integrated by an OEM.
 ===== PCB Dimensions =====
-All PCB's in the ICE Platform follow identical board dimensions and header/mounting hole locations. The PCB's themselves are 4 inches square and contain 4 mounting holes for 4-40 screws on each corner. All contain a power bus header on each side (Samtec PN: ESQ-106-13-T-D) and a digital communications bus header (Samtec PN: ESQ-104-13-T-D) in the middle of the PCB. These headers are 0.1 inch pitch board-to-board headers that allow interconnection between boards when stacked, as shown in the next section. At the edge of the board there are copper tabs extending from four IC's (TO-220 package) for heatsinking. Details on proper heatsinking are described in a [[pcb_mechanics#Thermal Management|later section]]. Note that not all boards will utilize all four heatsinking positions.
+All PCB's in the ICE Platform follow identical board dimensions and header/mounting hole locations. The PCB's themselves are 4 inches square and contain 4 mounting holes for 4-40 screws on each corner. The dimensions of the boards are shown in <imgref singlePCB>. All contain a power bus header on each side ([[http://cloud.samtec.com/catalog_english/ESQ_TH.PDF|Samtec PN: ESQ-106-13-T-D]]) and a digital communications bus header ([[http://cloud.samtec.com/catalog_english/ESQ_TH.PDF|Samtec PN: ESQ-104-13-T-D]]) in the middle of the PCB. These headers are 0.1 inch pitch board-to-board headers that allow interconnection between boards when stacked, as shown in the [[pcb_mechanics#PCB Stackup|next section]]. At the edge of the board there are copper tabs extending from four IC's (TO-220 package) for heatsinking. Details on proper heatsinking are described in a [[pcb_mechanics#Thermal Management|later section]].
-{{ :ice:single_pcb_dimensions.png |}}
-<WRAP round download 30%>
+<WRAP center round info 60%>
-{{:ice:ice_pcb_single_drawing_01.pdf|Technical Drawing}}
+Not all circuit boards will utilize all four heatsinking positions and therefore may have copper tabs in only a few positions. The four possible tab positions shown in the drawings will are fixed for every board even though a copper tab may not be utilized there.
 </WRAP>
-===== PCB Stackup =====
+<imgcaption singlePCB|PCB dimensions.>{{ :ice:single_pcb_dimensions.png?800 |}}</imgcaption>
-The PCB's are designed to stack on one another with each of the board-to-board headers mating, thereby forming a power distribution and communications bus between boards. The PCB's can be stacked by using 0.5 inch length 4-40 standoffs between boards in the four mounting holes at the corner. The maximum stack height is 9 boards total.
-<WRAP center round box 90%>
+<WRAP round download 30%>
-{{ :ice:stacked_pcb_dimensions.png |}}PCB stacking mechanics.
+{{:ice:ice_board_high_detail_01.pdf|Technical Drawing}}
 </WRAP>
+===== PCB Stackup =====
+The PCB's are designed to stack on one another with each of the board-to-board headers mating, thereby forming a power distribution and communications bus between boards. The PCB's can be stacked by using 0.5 inch length 4-40 standoffs ([[http://www.mcmaster.com/#93505a432/|McMaster-Carr PN: 93505A432]]) between boards in the four mounting holes at the corner as shown in <imgref stackedPCB>. The maximum stack height is 9 boards total.
+<imgcaption stackedPCB|PCB stacking mechanics.>{{ :ice:stacked_pcb_dimensions.png |}}</imgcaption>
 <WRAP round download 30%>
-{{:ice:ice_pcb_stack_drawing_01.pdf|Technical Drawing}}
+{{:ice:ice_board_high_detail_01_-_stack_of_9_boards_01.pdf|Technical Drawing}}
 </WRAP>
 ===== Thermal Management =====
-Each PCB exposes up to 4 copper tabs to conduct heat out from power dissipating components to an external heat sink. The copper tabs are not electrically isolated, so electrical isolation is required at the interface between the heatsink and copper tab. Failure to isolate these tabs will result in malfunction of the ICE module. For electrical isolation with good thermal conductivity, [[http://www.bergquistcompany.com/thermal_materials/sil-pad.htm|Sil-Pad]] can be used. Sil-Pad requires a certain amount of pressure to ensure good thermal conductivity, so a clamp mechanism should be applied to the copper tabs. In the [[ice:enclosure|ICE Platform]] enclosure, a wedge-based clamping system is used. The mechanics and dimensions of this are detailed below.
+Each PCB exposes up to 4 copper tabs to conduct heat out from power dissipating components to an external heat sink. The copper tabs are not electrically isolated, so electrical isolation is **required** at the interface between the heatsink and copper tab. Failure to isolate these tabs will result in malfunction of the ICE module. For electrical isolation with good thermal conductivity, [[http://www.bergquistcompany.com/thermal_materials/sil-pad.htm|Sil-Pad]] can be used. Sil-Pad requires a certain amount of pressure to ensure good thermal conductivity, so a clamp mechanism should be applied to the copper tabs. In the <imgref singlePCB> and <imgref stackup3>, the Sil-Pad is shown in pink. In the [[ice:enclosure|ICE Platform]] enclosure, a wedge-based clamping system is used. The mechanics and dimensions of this are detailed below
-<WRAP center round box 60%>
+<WRAP center round important 60%>
-{{ :ice:oem_heat_sinking_wedge_spec_-_image_01.png |}}Overall pcb heatsink stackup
+The copper tabs **must** be electrically isolated from the heatsink. For electrical isolation with good thermal conductivity, [[http://www.bergquistcompany.com/thermal_materials/sil-pad.htm|Sil-Pad]] can be used.
 </WRAP>
-<WRAP center round box 60%>
+<imgcaption stackup1|Overall pcb heatsink stackup.>{{ :ice:oem_heat_sinking_wedge_spec_-_image_01.png |}}</imgcaption>
-{{ :ice:oem_heat_sinking_wedge_spec_-_image_03.png |}}Top view of the stackup.
-</WRAP>
-<WRAP center round box 60%>
+<imgcaption stackup2|Top view of the stackup.>{{ :ice:oem_heat_sinking_wedge_spec_-_image_03.png |}}</imgcaption>
-{{ :ice:oem_heat_sinking_wedge_spec_-_image_07.png |}}Detail view of wedge clamp. Pink material is Sil-Pad for electrical isolation.
-</WRAP>
-<WRAP center round download 60%>
-{{:ice:oem_board_stack_-_heat_sinking_wedge_spec_-_drawing_01.pdf|Technical Drawing}}
-</WRAP>
+<imgcaption stackup3|Detail view of wedge clamp. Pink material is Sil-Pad for electrical isolation.>{{ :ice:oem_heat_sinking_wedge_spec_-_image_07.png |}}</imgcaption>
+<WRAP round download 30%>
+{{:ice:ice_heat_sinking_wedge_spec_-_drawing_01.pdf|Technical Drawing}}
+</WRAP>