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Vishay Electro-Films

Revision: 26-Sep-2018

2

Document Number: 61111

THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT

CURRENT DENSITY

To ensure optimal Resistor performance, the design engineer must consider the self-heating effects of the operating resistor

and understand the power dissipation characteristics of the environment. A complete thermal analysis should be performed by

the design engineer to ensure proper thin film resistor design. The following table lists current density standards for common

materials.

RESISTOR DESIGN

After the thin film resistor values have been determined and a metallization film selected per SPF1 and SPF2 datasheets, the

thin film resistor layout can be designed. There are two typical approaches for accomplishing this: the block-style resistor (see

Fig. 1) or serpentine- style resistor (see Fig. 2). With both design approaches, it is standard to employ a laser trim process to

trim the resistor to the desired value and tolerance. Vishay EFI employs both scrub (edge) trimming and plunge trimming

techniques to achieve the desired resistor value.

Fig. 1 - Probe pad and artwork overlap requirements (minimum)

Fig. 2 - Serpentine resistor with two areas for laser trim

All high frequency resistors should be Edge trimmed to value to preserve frequency response. VEFI can also supply resistors of

20 % tolerance (10 % special) or looser tolerances which are designed to 100 % of bake to value with no laser trimming.

CURRENT DENSITY

SHEET



RESISTANCE

SILICON

QUARTZ

AIN

BeO

25

/sq

4 mA/mil

20 mA/mil

0.5 mA/mil

19 mA/mil

32 mA/mil

50

/sq

2 mA/mil

10 mA/mil

0.25 mA/mil

9.5 mA/mil

16 mA/mil

100

/sq

1 mA/mil

5 mA/mil

0.125 mA/mil

4.7 mA/mil

8 mA/mil

200

/sq

0.5 mA/mil

2.5 mA/mil

0.062 mA/mil

2.3 mA/mil

4 mA/mil

Resistor length

0.002" (50.8 μm)

Artwork overlap

0.002" (50.8 μm)

0.0005"

(12.7 μm)

0.003"

(76.2 μm)

Probe

pad

Laser trim

example

Laser kerf=

0.0015"

(38.1μm)

Resistor squares

compensated

for laser kerf

Serpentine area

Link area

RESISTOR DESIGN RULES

PARAMETER

VALUES

COMMENTS

Min. resistor dimension

0.002" x 0.002" (50 μm x 50 μm)

Min. probe pad dimension

0.003" x 0.003" (75 μm x 127 μm)

For resistors < 1000

, use probe pad size of

0.006" (152 μm) x 0.008" (203 μm)

Min. conductor/resistor design overlap

0.002" (50 μm)

See Fig. 1

Resistor layout dimensions (block

resistor/serpentine resistor)

100 % of nominal value /

100 % of nominal resistor value plus laser

Resistor trim

Scrub, plunge, or bake to value

Bake to value ± 10 % or 20 %