VT33CT datasheet(72/76 Pages) PERKINELMER

72 / 76 page

Application Notes—Analog Optical Isolators

APPLICATION NOTE #2

Handling and Soldering AOIs

All opto components must be handled and soldered with care,

especially those that use a cast or molded plastic and lead frame

construction like the LEDs used in AOIs.

In LED lead frame construction, the emitter chip is mounted directly to

one lead and a wire bond is made from the chip to the other lead. The

encapsulating plastic is the only support for the lead frame. Care must

be taken when forming the leads of plastic opto packages. Excessive

mechanical force can cause the leads to move inside the plastic

package and damage the wire bonds. Weakened bonds can then

“open up” under further mechanical or thermal stressing, producing

open circuits.

In order to form leads safely, it is necessary to firmly lamp the leads

near the base of the package in order not to transfer any force

(particularly tension forces) to the plastic body. This can be

accomplished either through use of properly designed tooling or by

firmly gripping the leads below the base of the package with a pair of

needle nose pliers while the leads are being bent.

Examples of Tooling Fixtures Used to Form Leads

For highest reliability, avoid flush mounting the AOI body on the printed

circuit board. This minimizes mechanical stress set up between the

circuit board and the LED and photocell packages. It also reduces

solder head damage to the packages.

Good printed circuit board layout avoids putting any spreading (plastic

under tension) force on the leads of the LED and photocell.

When hand soldering, it is important to limit the maximum temperature

of the iron by controlling the power. It is best if a 15W or 25W iron is

used. The maximum recommended lead soldering temperature (1/16"

from the case for 5 seconds) is 260°C. An RMA rosin core solder is

recommended.

Sn60 (60% tin / 40% lead) solder is recommended for wave soldering

opto components into printed circuit boards. Other alternatives are

Sn62 and Sn63. The maximum recommended soldering temperature

is 260°C with a maximum duration of 5 seconds.

The amount of tarnish on the leads determines the type of flux to use

when soldering devices with silver plated leads.

Cleaners designed for the removal of tarnish from the leads of

electronic components are acidic and it is best to keep the immersion

time as short as possible (less than 2 seconds) and to immediately

wash all devices thoroughly in ten rinses of deionized water.

Condition of Leads

Recommended Flux

Clear Bright Finish

(Tarnish Free)

RMA - Mildly Activated

Dull Finish

(Minimal Tarnish)

RMA - Mildly Activated

Light Yellow Tint

(Mild Tarnish)

RA - Activated

Light Yellow / Tan Color

(Moderate Tarnish)

AC - Water Soluble,

Organic Acid Flux

Dark Tan / Black Color

(Heavy Tarnish)

Leads Need to be Cleaned

Prior to Soldering

VT33CT Datasheet(PDF) 72 Page - PerkinElmer Optoelectronics

VT33CT Datasheet(HTML) 72 Page - PerkinElmer Optoelectronics

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