V5X5P, V15X5P, V15X10P
Vishay Foil Resistors
Bulk Metal
®
Foil Technology Discrete Chips
with TCR of 2 ppm/°C and Tolerance to 0.005 %
for use in Hybrid Circuits
www.vishay.com For any questions, contact: foil@vishay.com
Document Number: 63024
6 Revision: 25-Oct-07
EFFECTS OF GOLD WIRE
The bonding of the gold wires to the chip has an effect on the overall resistance and on the temperature coefficient, according to
the length of wire used.
The nomogram below shows the effect on both parameters with varying lengths of 0.001" (0.0254 mm) diameter gold wire.
NOMOGRAM
Change of resistance and TCR due to a length L of gold wire added at wire bonding.
500
360
250
160
120
90
62.5
40
22.5
10
50
23
16
10.5
6
4
2.25
1.40
0.82
0.47
0.30
0.16
0.11
600
350
225
130
85
41
25
16
10
6
1900
1100
610
400
230
150
85
53
31
18
11
6.1
4.2
2.3
1.5
0.85
0.50
0.32
0.15
0.10
0.06
0.04
0.02
1
1.4
2.2
3.2
4
6.2
9
12.2
16
25
36
49
64
81
100
144
225
324
400
625
900
1.2K
1.6K
2.5K
3.6K
4.9K
6.4K
8.1K
10K
14.4K
22.5K
32.4K
40K
ppm
%
A
B
R
Δ
TCR
ppm/°C
Δ
R
R
L
thousandths of an inch
total length of 2 gold
wires of 0.001
" diameter
nominal resistance of
chip as measured on its
pads (Ω)
EXAMPLE:
Total length of wires L = 0.100" (point A on left scale)
Resistance of chip R = 200 Ω (point B on right scale)
Read on intersection of line as with central scale:
On left side - change of resistance:
ΔR
R
On right side - change of TCR:
ΔTCR = ± 2.3 ppm
Nomogram based on the following specs for gold wire:
• Conductivity 72 % of copper
• 1.2 Ω/inch for 0.001" (0.0254 mm) diameter wire
• TCR 3900 ppm/°C
= 600 ppm
