Transistor Packages

TO-276 Body style Transistor or FET SMD package

Package Out-line and Dimensions for a TO-276 Transistor
TO-276 Package Drawing and Package Dimensions

The TO-276 package is a 3-terminal surface mount component. The complete package name for this style is TO-276AA, as there are additional variants which will not adhere to these dimensions. The previous name used for this component package was SMD05, or SMD0.5. The TO-205 appears to be an identical package.

Case temperature. Because the TO-276 is a Surface Mount Device [SMD] heat transfer will also be conducted via the component pads. There are no leads to shorten to increase heat conduction as in a thru-hole component. The TO-276 has to be mounted to a Printed Circuit Board [PCB] so the lands or PWB pads are used to transfer heat. For best results use the largest pads possible while keeping the required spacing between pads.

The weigh of the copper [copper thickness] is of marginal help with 3oz copper providing the same heat transfer as 1oz copper. However the surface area of the PCB pads makes all the difference in conducting heat. The larger the pad surface area, the lower the thermal resistance. Heat conduction increases as thermal resistance decreases.
Refer to Thermal Resistance by Pad Area by Copper Weight graph.

The text above indicates that this package is used by either transistors or FETs but almost any two or three terminal semiconductor could use this package: Thyristors, IGBTs and so on. A single diode using pin 1 for the anode and pins 2 and 3 for the cathode. A common cathode diode pair with the cathode(s) on pin 1 and the individual anodes to pins 2 and 3 [1N6828, 1N6833].

Component Part Numbers

Surface Mounted Dual Schottky Center Tap Power Rectifier Diode; 1N6840U3, 1N6841U3
Semiconductor Diode, Power Rectifier, Common Cathode or Anode Center Tap; 1N6828, 1N6833 [part numbers are only used to provide examples]
Transistor, Field Effect Radiation Hardened (Total Dose Only), P-Channel 2N7422-U, 2N7423-U
N-Channel Field Effect Transistor Radiation Hardened (Total Dose and Single Event Effects), 2N7468U2 and 2N7469U2
N-Channel Field Effect Transistor Radiation Hardened (Total Dose and Single Event Effects), 2N7479U3, 2N7480U3, and 2N7481U3
N-Channel Repetitive Avalanche Field Effect Transistor 2N7224-U, 2N7225-U, 2N7227-U, 2N7228-U [the letter designation may indicate a version, or pin orientation]
P-Channel Repetitive Avalanche Field Effect Transistor 2N7236-U, 2N7237-U

Transistor Package
Ceramic No Lead Chip Carrier

1N6828 Dual Diode Package Schematic
SMD05 Schematic

Related BJT Topics:
Transistor Derating Guidelines
Including Thermal definitions

Types of Transistor cases and FET cases
Manufacturers of FETs and BJTs
Thermal Compounds


PC motherboard

Distributor rolodex Electronic Components Electronic Equipment EDA CDROM Software Engineering Standards, BOB card Cabled Computer Bus Electronic Engineering Design Table Conversion DB9-to-DB25.
DistributorsComponents Equipment Software Standards Buses Design Reference

Modified 6/13/15
© 1998 - 2016 All rights reserved Larry Davis