electronics:torque_standards_for_power_packages
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electronics:torque_standards_for_power_packages [2022/06/02 22:27] – [Infineon] mithat | electronics:torque_standards_for_power_packages [2024/01/18 02:46] – [STMicroelectionics] mithat | ||
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====== Torque Standards for Power Packages ====== | ====== Torque Standards for Power Packages ====== | ||
- | ===== Recommendations ===== | ||
<WRAP center round info 60%> | <WRAP center round info 60%> | ||
The recommendations below are based on current data. As more sources are found, these recommendations may change. | The recommendations below are based on current data. As more sources are found, these recommendations may change. | ||
</ | </ | ||
- | The best data appears to be that provided in STMicroelectronics' | + | ===== Recommendations |
- | + | ||
- | ^ Package | + | |
- | |TO-220 | + | |
- | |TO-220SG | + | |
- | |Pentawatt | + | |
- | |Heptawatt | + | |
- | |TO-220FP | + | |
- | |ISOWATT220 | + | |
- | |TO-247 | + | |
- | |TO-218 | + | |
- | + | ||
- | Use of M3 screws is assumed in the data above. However, using #4-40 screws (about 5% thinner than M3) with proper washers shouldn' | + | |
- | + | ||
- | ===== Discussion of data from sources | + | |
==== STMicroelectionics ==== | ==== STMicroelectionics ==== | ||
- | STMicroelectionics gives the following guidelines | + | Comprehensive data and test results |
^ 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 | ||
- | The kind of insulator (mica, silicone, etc.) isn't specified | + | The kind of insulator (mica, silicone, etc.) isn't specified. |
+ | {{: | ||
- | A different | + | STMicroelectronics' AN260 reference provides empiric data for a number of packages |
However, the maximum torque is slightly contradicted here (emphasis added): | However, the maximum torque is slightly contradicted here (emphasis added): | ||
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> 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). | > 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 | + | This leads to the following |
+ | |||
+ | ^ Package | ||
+ | |TO-220SG | ||
+ | |TO-220 | ||
+ | |Pentawatt | ||
+ | |Heptawatt | ||
+ | |Multiwatt | ||
+ | |Clipwatt | ||
+ | |FLEXIWATT | ||
+ | |||
+ | The hardware stackup shows only a screw entering | ||
+ | |||
+ | {{: | ||
+ | ===== Data from other sources ===== | ||
==== Infineon ==== | ==== Infineon ==== | ||
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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.)) introduces 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