Diode Package Styles

DO-35 Diode Package Details

Diode Package DO-35 Case style, Through-Hole

DO-35 Diode Package Outline and Dimensions
DO-35 Diode, Axial Lead Component Package

The DO-35 package is a 2-terminal Axial Leaded Through-Hole device.

The leads should be bent near the component body to keep them as short as possible, and also insure the body is raised up just above the surface of the PWB. The short leads between the DO-35 and the Printed Circuit Board [PCB] allow good heat conduction into the board [Horizontal mounting]. Vertical mounting is also possible and results in more efficient heat conduction than horizontal mounting because of the single short lead. The shorter the leads the lower the thermal resistance between the DO-35 body and the PCB.
Refer to the graph below for lead length vs heat transfer, for equal length leads. Note that the DO-34 package is the exact same style with slightly different dimensions, as shown in the table to the left.

Copper heat sinks are available for axial leaded components, mounted horizontally to the board.

A number of diodes use the DO-35 package;
Low-Noise Voltage Regulator Diodes; 1N4099-1 through 1N4135-1, 1N4614-1 through 1N4627-1, 1N5518B-1, 1N5518C-1, 1N5518D-1 to 1N5546B-1, 1N5546C-1 and 1N5546D-1
Ultra-Fast-Recovery Power Rectifier Diode; 1N6073 through 1N6081
Voltage Regulator Diode; 1N6309 through 1N6355, 1N962 through 1N992
Voltage Regulator Diode, 500mW; 1N4370A-1 to 1N4372A-1, 1N746A-1 to 1N759A-1,
Zener Diodes; 1N5221B to 1N5267B
Schottky Barrier Hermetic Diode, 1N6677-1
500mW Diodes; 1N4614, 1N4615, 1N4616, 1N4617, 1N4618, 1N4618, 1N4619, 1N4620
1N4621, 1N4622, 1N4623, 1N4624, 1N4625, 1N4626, 1N4627, 1N4678

Similar components are provided for rapid substitution if required because of lead time, stock issues or obsolescence, but does not imply they are in production.

Editor note; Some data sheets may refer to a Zener diode as a voltage regulator diode, while other data sheets or companies may just use the term Zener diode.

DO-35 Diode Package Derating

DO-35 Diode Package Temperature-Power Derating Curve

DO-35 Axial Leaded Temperature-Power Derating Curve
DO-35 Diode Power Derating Curve

How to read the temperature curves; Interpreting Deraring Curves.

How to derate a Axial Lead Through-Hole DO-35 package based on operating temperature. Derate Temperature by Device; Diode Derating Curves
The graph applies to still air, so supplying forced air to the system will allow the DO-35 to operate at a higher temperature then shown in the graph.

Take note that there could be other derating curves that relate to a DO-35 that look different, with the operating range falling at different rates. Although this curve does show the operating range of a DO-35, it also indicates the lead length of 3/8 inch and the thermal resistance. Other curves may indicate a different thermal resistance, a different lead length or relate to the temperature rise of the printed circuit card and not the component it self. The important point to note is that this graph relates to a board mounted DO-35 with a particular lead length [both terminals being the same length].

DO-35 Style Package Drawing
Axial Lead DO-35 Diode Package

Also see Styles of Diode Packages, or How to Derate; Guideline for Derating Components.

Editor note: As with all these curves provided on this site, the top most curve [far right] represents the maximum junction temperature of 175 degrees Centigrade and should not be used and never be exceeded. The curve just under that which intersects with 150 degrees and indicates the point that all the electrical characteristics were derived. The two bottom gray curves indicate the best range that the DO-35 should be operated at, as power and temperature.

This page is one of about half a dozen that describe power derating of a component body without regard to an associated semiconductor. The data is a bit hard to design with, but the information does show how the size and shape of a part and its lead length come into play when thinking of over temperature and proper design.

The leads of the DO-35 do help to conduct heat away from the body of the component. However the greatest amount of heat conduction occurs using the shortest lead length possible [conducting heat into the Printed Wiring Board]. Refer to a graph to the left, as Lead Length vs Power Dissipation for an axial lead DO-35 diode [1N6073, 1N6074, & 1N6075]. The thermal resistance of the Junction to Lead [JL] increases with lead length. The thermal resistance of the leads for a lead length of zero begins at 13C/W, and increases to 70 C/W for a lead length of 0.75 inches. The other lead lengths provided in the graph equate to the following thermal resistances: .125, 13C/W; .250, 24C/W; .375, 46C/W; and .5, 54C/W. Heat is also removed from the DO-35 body by convection and radiation.

The maximum power the diode can dissipate decreases as the lead length increases. Heat is transferred from the body of the component through the leads and into the Printed Circuit Board [PCB] which is why lead length is important. The longer the component terminals the greater the resistance to heat flow from the body of the device. Always use the shortest possible lead length during PWB layout and design [something that would need to specified]. Also avoid using component sockets or discrete carriers and mount the diode directly to the printed wiring board, because the socket adds additional thermal resistance. When one terminal of the diode connects to power or ground take that lead directly to the voltage plane if possible

Axial Lead Component

DO-34 Diode Package Dimensions
DO-34 Diode Package Dimensions

Diode Topics:
Types of Diode cases
Diode Derating Guidelines
Diode Derating Curves
Diode Manufacturers
Voltage Regulators
Zener Diode Manufacturers
Zener Diode Terms

Note the lead length in the chart.
Greatly effecting heat transfer

Example diodes in this package:
500mW voltage regulator diodes

1N962, 1N963, 1N964, 1N965, 1N966,
1N967, 1N968, 1N969, 1N970, 1N971,
1N972, 1N973, 1N974, 1N975, 1N976,
1N977, 1N978, 1N979, 1N980, 1N981,
1N982, 1N983, 1N984, 1N985, 1N986,
1N987, 1N988, 1N988, 1N989, 1N990.

Available as a B-1 or C-1 suffix.
Suffix omitted to be brief.

DO-35 junction temperature vs. lead length
DO-35 Axial Lead Length vs. TJ
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Modified 6/13/15
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