MIL-PRF-19500-411 Semiconductor Device, Diode, Silicon, Power Rectifier, Fast Recovery, 1N5415 Through 1N5420, 1N5415Us Through 1N5420Us, Jan, Jantx, Jantxv, Jans, Jantxvm, Jantxvd, Jantxvr, Jantxvh, Jansm, Jansd, Jansr, And JanshThis specification covers the performance requirements for silicon rectifier diodes. Four levels of product assurance are provided for each device type as specified in MIL-PRF-19500. Provision for radiation hardness assurance \(RHA\) to four radiation test levels is provided for JANTXV and JANS product assurance levels. RHA level designators "M", "D", "R", and "H" are appended to the device prefix to identify devices which have passed RHA requirements.

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MIL-PRF-19500/411R

6.4 Application data.

6.4.1 PCB mounting with FR4 material for full 3 amp IO. For a PCB mounting example with FR4 material

where the full 3 amp IO rating (half-sine-wave) is used at a TJ of 175�C and ambient temperature of 55�C, the

following steps guide the user in what the PCB pad size will need to be with 1 oz, 2 oz, and 3 oz copper.

For axial-leaded, the lead length for mounting will be .187 inch (4.76 mm) or less from body to entry point on

PCB surface.

Use the IO versus Po curve on figure 5 to look up 3 amps (X-axis) and follow up to the TJ = +175�C

curve (lower) for 2.81 watts.

Calculate maximum thermal resistance needed (+175�C - 55�C) / 2.81 W = 43�C/W.

Look up thermal resistance of 43�C/W on Y-axis using a thermal resistance versus pad area plot on

one of the three curves on figure 6 for different weights of copper cladding and then intersect curve

horizontally to get answer. These curves assume still air, horizontal position.

In this example, the answer is: 1 oz PCB = 1.00 in x 1.00 in (25.4 mm x 25.4 mm), 2 oz PCB = .50 in x .50

in (12.7 x 12.7 mm), 3 oz PCB = .32 in x .32 in (8.128 x 8.128 mm) for each pad.

Add a conservative guard-band to the pad size (larger) to keep TJ below +175�C.

6.4.2 PCB mounting with FR4 material for 1 amp IO. For a PCB mounting example with FR4 material to support a

1 amp IO square wave switching at a 0.50 duty factor (50 percent duty cycle) at TJ = +125�C and ambient temperature

of +55�C, the following steps guide the user in what the PCB pad size will need to be with 1 oz, 2 oz, and 3 oz

copper.

Find size of copper pads on standard FR4 PCB to support operation at 1 amp IO square wave switching at a

0.50 duty factor (50 percent duty cycle) at TJ = +100�C with TA = +55�C.

Calculate peak IF = 1A / 0.50 duty factor = 2 amps.

Use the VF versus IF curve on figure 7 to look up IF = 2 A (Y-axis) and follow across to the TJ = +125�C curve

(middle) for VF = 0.775 V.

Calculate power = IF x VF x duty factor = 2 x 0.775 x 0.50 = 0.775 W.

Calculate maximum thermal resistance needed (+100�C - 55�C) / 0.775 W = 58�C/W.

Look up thermal resistance of 90�C/W on the Y-axis using a thermal resistance versus pad area plot on one

of the three curves on figure 7 for different weights of copper cladding and then intersect curve horizontally

to get answer. Curves assume still air, horizontal position.

In this example, the answer is: 1oz PCB = .092 in X .092 in (2.34 mm x 2.34 mm), 2oz PCB = .055 in x .055

in (1.4 mm x 1.4 mm), 3oz PCB = .036 in x .036 in (0.91 mm x 0.91 mm) for each pad.

A conservative pad guard-band is optional since TJ is only +100�C. NOTE: Multilayer PCBs, forced air

cooling will improve performance. Closed confinement of the PCB will do the opposite. Use sound thermal

management.