electronics:torque_standards_for_power_packages
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
electronics:torque_standards_for_power_packages [2022/06/07 14:42] – [Recommendations] mithat | electronics:torque_standards_for_power_packages [2024/01/18 02:50] (current) – [onsemi] mithat | ||
---|---|---|---|
Line 7: | Line 7: | ||
===== Recommendations ===== | ===== Recommendations ===== | ||
- | The best data appears to be that provided in STMicroelectronics' | + | ==== STMicroelectionics ==== |
+ | |||
+ | Comprehensive | ||
^ Package | ^ Package | ||
|TO-220 | |TO-220 | ||
- | |TO-220SG | ||
- | |Pentawatt | ||
- | |Heptawatt | ||
|TO-220FP | |TO-220FP | ||
- | |ISOWATT220 | ||
|TO-247 | |TO-247 | ||
- | |TO-218 | 0.55 | 1.00 | | + | |TO-247-4 | 0.55 | 1.00 | |
+ | |TO-3P | ||
+ | |TO-3PF | ||
- | Use of M3 screws is assumed | + | The kind of insulator (mica, silicone, etc.) isn't specified. |
+ | {{: | ||
- | ===== Discussion | + | STMicroelectronics' |
- | ==== STMicroelectionics ==== | + | However, the maximum torque is slightly contradicted here (emphasis added): |
- | STMicroelectionics gives the following guidelines | + | > Suggested maximum torques |
+ | |||
+ | This leads to the following table for packages | ||
^ Package | ^ Package | ||
- | |TO-220 | ||
|TO-220SG | |TO-220SG | ||
- | |Pentawatt | + | |TO-220 |
- | |Heptawatt | + | |Pentawatt |
- | |TO-220FP | + | |Heptawatt |
- | |ISOWATT220 | + | |Multiwatt |
- | |TO-247 | + | |Clipwatt |
- | |TO-218 | + | |FLEXIWATT |
- | The kind of insulator (mica, silicone, etc.) isn't specified for these data. | + | The hardware stackup shows only a screw entering the device tab through an optional washer and a bolt on the heatsink side: |
- | A different STMicroelectronics reference provides empiric data for a number of packages over a range of torques using mica insulators.(([[https:// | + | {{:electronics: |
- | + | ===== Data from other sources ===== | |
- | However, the maximum torque is slightly contradicted here (emphasis added): | + | |
- | + | ||
- | > Suggested maximum torques for M3 screws are //80Nxcm// for TO220, PENTAWATT, HEPTAWATT, MULTIWATT and CLIPWATT 19 H packages. Particularly for FLEXIWATT package, clipping system is strongly recommended. While suggested maximum torque for M3 screws is 70 Nxcm for TO220SG (single gauge). | + | |
- | + | ||
- | The data given in the table above is the more conservative and therefore preferred. | + | |
==== Infineon ==== | ==== Infineon ==== | ||
Line 55: | Line 52: | ||
TI mentions 50N-cm as the recommended maximum for their multi-lead TO-247 packages.(([[https:// | TI mentions 50N-cm as the recommended maximum for their multi-lead TO-247 packages.(([[https:// | ||
+ | ==== onsemi ==== | ||
+ | onsemi' | ||
+ | For Power Semiconductors]]. onsemi. Accessed Jan 17, 2024.)) advocates the use of conical " | ||
+ | |||
+ | {{: | ||
+ | |||
+ | However, the text implies that torque cannot be used to set the device pressure with conical washers because, "The assembler applies torque until the washer depresses to half its original height. (Tests should be run prior to setting up the assembly line to determine the proper torque for the fastener used to achieve 50% deflection." | ||
+ | |||
+ | Perhaps not surprisingly then, specific torque ratings are difficult to derive from this note. However, it shows for TO-220 packages remarkable consistent thermal resistances for greased mica mounting with unspecified hardware over 2 to 6 in-lbs (0.23 to 0.68 N*m). One table shows a torque of 8 in-lbs (0.90 N*m) used with a TO−220AB device. | ||
electronics/torque_standards_for_power_packages.txt · Last modified: 2024/01/18 02:50 by mithat