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Assembly Instructions
Vishay Semiconductors

Assembly Instructions
GENERAL
Vishay offers a wide product selection of optocouplers and solid state relays in a variety of packages. This document provides instructions on mounting for the different types of packages, specifically on the different methods of soldering. For DIP packages, they can be mounted in DIP sockets or directly on a pre-designed PCB with holes. The preferred solder process for SMD packages is reflow soldering. Certain SMD families are also qualified for wave soldering; please see table 1. The moisture sensitivity Level (MSL) = 1 for all couplers. If the device is to be mounted near heat-generating components, consideration must be given to the resultant increase in ambient temperature. Influencing parameters on the internal temperature of the component are as follows: Time and power Mass of the component Size of the component Size of the printed circuit board Absorption coefficient of the surfaces Packing density Wavelength spectrum of the radiation source Ratio of radiated and convected energy Temp
erature/time profiles of the entire process and the influencing parameters are given. The IR reflow profile is shown in figure 1. Two cycles of reflow are allowed. (c) Wave soldering In wave soldering one or more continuously replenished waves of molten solder are generated, while the substrates to be soldered are moved in one direction across the crest of the wave. Maximum soldering temperature should not exceed 260 C. Temperature/time profiles of the entire process are given in figure 2. For SMD devices which are qualified for wave soldering, the temperature profile under figure 2 is also valid. For wave soldering two cycles are allowed. (d) Iron soldering This process cannot be carried out in a controlled situation. It should therefore not be used in applications where reliability is important. There is no SMD classification for this process. (e) Laser soldering This is an excess heating soldering method. The energy absorbed may heat the device to a much higher temperature than desired. There is no SMD c
lassification for this process at the moment. (f) Resistance soldering This is a soldering method which uses temperature-controlled tools (thermodes) for making solder joints. There is no SMD classification for this process at the moment.

SOLDERING INSTRUCTIONS
Protection against overheating is essential when a device is being soldered. Therefore, the connection wires or PCB traces should be left as long as possible. The maximum permissible soldering temperature is governed by the maximum permissible heat that may be applied to the package. The maximum soldering iron (or solder bath) temperatures are given in the individual datasheets. During soldering, no forces must be transmitted from the pins to the case (e.g., by spreading the pins).

SOLDERING METHODS
There are several methods for soldering devices onto the substrate. The following is a partial list. (a) Soldering in the vapor phase Soldering in saturated vapor is also known as condensation soldering. This soldering process is used as a batch system (dual vapor system) or as a continuous single vapor system. Both systems may also include a pre-heating of the assemblies to prevent high-temperature shock and other undesired effects. (b) Reflow soldering of lead (Pb)-free SMD devices By using infrared (IR) reflow soldering, the heating is contact-free and the energy for heating the assembly is derived from direct infrared radiation and from convection. The heating rate in an IR furnace depends on the absorption coefficients of the material surfaces and on the ratio of the component's mass to an as-irradiated surface. The temperature of parts in an IR furnace, with a mixture of radiation and convection, cannot be determined in advance. Temperature measurement may be performed by measuring the temperature of a
certain component while it is being transported through the reflow oven.

Document Number: 80054 Rev. 1.6, 24-Nov-08

For technical questions, contact: optocoupler.answers@vishay.com

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