(7/12)

20220209 / vpd_varistors_avr_en.fm

Please be sure to request delivery specifications that provide further details on the features and specifications of the products for proper and safe use.

Please note that the contents may change without any prior notice due to reasons such as upgrading.

Voltage Protection Devices

Chip varistors

Board design

When attached to chip varistors, amount of silver used (fillet size)

has direct impact on chip varistors after mounting. Thus, sufficient

consideration is necessary.

Set of land dimensions

(1) As the stress rises in the chip varistors owing to the increase in

silver, breakage and cracks will occur. Cause including crack, as

caution on board land design, configure the shape and dimensions

so that the amount of silver is appropriate. If you installed 2 or

more parts in the Common Land, separated by a solder resist and

special land of each component.

(2) When peak levels panning-at soldering is excessive, by solder

contraction stress, mechanical-thermal stress causes a Yasuku

chip crack. In addition, when the peak level is underestimated, ter-

minal electrode fixed strength is insufficient. This causes

chip

dropouts and may affect circuit reliability. Representative example

of the panning of peak levels is shown in the following.

Recommended silver dose

Case and suggested protocol want to avoid

Attention on a circuit board design

RoHS Directive Compliant Product

Compatible with lead-free solders

Dimensions shape

Symbol

A

B

C

0402

0.20 Nom.

0.15 to 0.21

0.18 to 0.20

0603

0.25 to 0.35

0.20 to 0.30

0.25 to 0.35

1005

0.30 to 0.50

0.35 to 0.45

0.40 to 0.60

1608

0.60 to 0.80

0.60 to 0.80

0.60 to 0.80

2012

0.90 to 1.20

0.70 to 0.90

0.90 to 1.20

A

B

C

Solder volume

overload

Solder stress is increased,

and it is easy for a crack to

form.

Decent solder

volume

Solder volume

deficit

Fixed strength is weak, and

there is connection a prob-

lem and risk of loss.

Example

Cases to avoid

Improvement example

(land division)

Lead wire and land

of part discrete

doubles up

Arrangements in

the vicinity

Arrangements of

chip component's

companion

Most large serving amount

Minimum prime amount

Solder

Chip

Leads

PCB

Solder resist

Leads

Solder

(ground solder)

Chassis

L1

Solder resist

L2

L2>L1

Land

Land

Excess solder

Missing solder

Solder resist