Differences

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

--- ice:pcb_mechanics [2014/07/02 18:19] – [PCB Stackup] jtshugrue
+++ ice:pcb_mechanics [2014/07/02 18:24] – Added another sil pad figure ref jtshugrue
@@ 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. 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]]. 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]].
+<WRAP center round info 60%>
+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>
 <imgcaption singlePCB|PCB dimensions.>{{ :ice:single_pcb_dimensions.png?800 |}}</imgcaption>
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 </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 <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
+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 important 60%>
 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.