Assembly Instructions Vishay Semiconductors Assembly Instructions GENERAL Optoelectronic semiconductor devices can be mounted in any position. Connection wires may be bent provided the bend is not less than 1.5 mm from bottom of case. During bending, no forces must be transmitted from pins to case (e.g., by spreading the pins). If the device is to be mounted near heat generating components, the resultant increase in ambient temperature should be taken into account. SOLDERING INSTRUCTIONS Protection against overheating is essential when a device is being soldered. It is recommended, therefore, that the connection wires be left in place as long as possible. The maximum permissible device junction temperature should be exceeded for as little time as possible, and for no longer than specified in the solder profiles, during the soldering process. In case of plastic encapsulated devices, the maximum permissible soldering temperature is governed by the maximum permissible heat that may be applied to encapsulants rather than by the maximum permissible junction temperature. Maximum soldering iron (or solder bath) temperatures are given in table 1. During soldering, no forces must be transmitted from pins to case (e.g., by spreading pins). Infrared soldering With 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 (Refer to CECC00802). The heating rate in an IR furnace depends on the absorption coefficients of the material surfaces and on the ratio of component’s mass to its irradiated surface. The temperature of components 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 furnace. The temperatures of small components, soldered together with larger ones, may rise up to 280 °C. The following parameters influence the internal temperature of a component: - Time and power - Mass of component - Size of component - Size of printed circuit board - Absorption coefficient of surfaces - Packaging density SOLDERING METHODS - Wavelength spectrum of radiation source There are several methods in use to solder devices onto the substrate. Some of them are listed in the following sections. - Ratio of radiated and convected energy Vapor Phase Soldering Temperature-time profiles of the entire process and the above parameters are given in figures 1 and 2. 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 preheating of the assemblies to prevent high-temperature shock and other undesired effects. TABLE 1- MAXIMUM SOLDERING TEMPERATURES IRON SOLDERING Devices in metal case Devices in plastic case > 3 mm Devices in plastic case ≤ 3 mm www.vishay.com 52 WAVE SOLDERING IRON TEMPERATURE DISTANCE OF THE SOLDERING POSITION FROM THE LOWER EDGE OF THE CASE MAXIMUM ALLOWABLE SOLDERING TIME SOLDERING TEMPERATURE SEE TEMPERATURE TIME PROFILES DISTANCE OF THE SOLDERING POSITION FROM THE LOWER EDGE OF THE CASE MAXIMUM ALLOWABLE SOLDERING TIME ≤ 245 °C ≥ 1.5 mm 5s ≤ 245 °C ≥ 5.0 mm 10 s 245 °C ≥ 1.5 mm 5s ≤ 350 °C ≥ 5.0 mm 5s 300 °C ≥ 5.0 mm 3s ≤ 260 °C ≥ 2.0 mm 5s 235 °C ≥ 2.0 mm 8s ≤ 300 °C ≥ 5.0 mm 3s 260 °C ≥ 2.0 mm 5s ≤ 300 °C ≥ 5.0 mm 3s 260 °C ≥ 2.0 mm 3s For technical questions concerning emitters, contact: [email protected] For technical questions concerning detectors, contact: [email protected] Document Number: 80080 Rev. 1.3, 28-Aug-08 Assembly Instructions Assembly Instructions Vishay Semiconductors TEMPERATURE-TIME PROFILES 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 wave’s crest. Temperature-time profiles of the entire process are given in figure 3. Iron soldering This process cannot be carried out in a controlled way. It should not be considered for use in applications where reliability is important. There is no SMD classification for this process. 300 200 max. 30 s 150 max. ramp up 3 °C/s max. ramp down 6 °C/s 50 Resistance soldering max. 100 s max. 120 s 100 Laser soldering This is an excess heating soldering method. The energy absorbed may heat device to a much higher temperature than desired. There is no SMD classification for this process at the moment. max. 260 °C 245 °C 255 °C 240 °C 217 °C 250 Temperature (°C) Wave soldering 0 0 50 100 19841 150 200 250 300 Time (s) Fig. 1 - Lead (Pb)-free (Sn) Infrared Reflow Solder Profile acc. J-STD020D for Surface-Mount Components 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. 260 240 Surface-mount devices are sensitive to moisture release if they are subjected to infrared reflow or a similar soldering process (e.g. wave soldering). After opening the bag, they must be: 1. stored at ambient of < 20 % relative humidity (RH) Temperature (°C) 220 WARNING 200 - 5 °C/s + 5 °C/s 180 160 140 120 2. mounted within floor life specified on MSL sticker under factory conditions of Tamb < 30 °C/RH < 60 % 100 Devices require baking before mounting if 1. or 2. is not met and the humidity indicator card is > 20 % at 23 ± 5 °C. If baking is required, devices may be baked for 192 h at 40 °C + 5 °C - 0 °C and < 5 % RH. 60 60 s to 120 s 5s 80 0 20 40 60 80 100 120 140 160 180 200 220 Time (s) 17172 Fig. 2 - Infrared Reflow SnPb Solder Profile for Surface-Mount Components like TEMx1xxx and TSMx1xxx 300 5s Lead temperature Temperature (°C) 250 235 °C to 260 °C first wave 200 wave ca. 200 K/s 150 100 °C to 130 °C 100 ca. 2 K/s 2 K/s 50 full line: typical dotted line: process limits second wave ca. 5 K/s forced cooling 0 0 948626 50 100 150 200 250 Time (s) Fig. 3 - Double Wave Solder Profile for Leaded Components Document Number: 80080 Rev. 1.3, 28-Aug-08 For technical questions concerning emitters, contact: [email protected] For technical questions concerning detectors, contact: [email protected] www.vishay.com 53 Assembly Instructions Assembly Instructions Vishay Semiconductors HEAT REMOVAL Lead Length at Different Assembly To maintain thermal equilibrium, the heat generated in the semiconductor junction(s) must be removed to keep the junction temperature below specified maximum. In case of low-power devices, the natural heat conductive path between the case and surrounding air is usually adequate for this purpose. The heat generated in the junction is conveyed to the case or the header by conduction rather than convection. A measure of the effectiveness of heat conduction is the inner thermal resistance or the junction-to-case thermal resistance, RthJC, which is governed by the device construction. Any heat transfer from the case to the surrounding air involves radiation convection and conduction, the effectiveness of transfer being expressed in terms of an RthCA value, i.e., external or case ambient thermal resistance. The total junction-to-ambient thermal resistance is consequently: 94 8162 l 3 ≥ 100 0.14 mm 2 Cu isolated Fig. 5 - In Case of Wire Contacts (Curve B, Figure 4) RthJA = RthJC + RthCA The total maximum power dissipation, Ptotmax. of a semiconductor device can be expressed as follows: Ptotmax . T T 2.5 From underneath T T RthJC RthCA – jmax . – amb j max . amb = -------------------------------------------------------- = ----------------------------------------------------------+ RthJA 2.54 where: Tjmax. the maximum allowable junction temperature Tamb the highest ambient temperature likely to be reached under the most unfavorable conditions RthJC junction-to-case thermal resistance RthJA the junction-to-ambient thermal resistance, is specified for the components. The following diagram shows how the different installation conditions effect the thermal resistance RthCA Side view l the case-to-ambient thermal resistance, RthCA, depends on cooling conditions. If a heat dissipator or sink is used, RthCA depends on the thermal contact between the case and heat sink, upon the heat propagation conditions in the sink, and upon the rate at which heat is transferred to the surrounding air 94 8163 Fig. 6 - In Case of Assembly on PC Board, no Heatsink (Curve C, Figure 4) Cu 2.5 From underneath 100 RthJA (%) b 2.54 100 mm2 90 c Cathode a l Side view 80 5 94 8161 15 25 Fig. 4 - Junction-to-Ambient Thermal Resistance vs. www.vishay.com 54 94 8164 Length l (mm) Fig. 7 - In Case of Assembly on PC Board, with Heatsink (Curve A, Figure 4) For technical questions concerning emitters, contact: [email protected] For technical questions concerning detectors, contact: [email protected] Document Number: 80080 Rev. 1.3, 28-Aug-08