Installation Precautions

Transcription

1 Installation Precautions 1. Lead orming (1) Avoid bending the leads at the base and ensure that the leads are fixed in place. (2) Bend the leads at a point at least 2mm away from the base. (3) orm the leads before soldering. Side Bending tool Clinch the lead terminal with the bending tool (bending stress) Not Recommended (bending stress) Recommended 2. Installation TIP Refrain from installing such that stress is applied to the lead terminals. Case (1) When inserting into a substrate, ensure that the terminal pitch matches the substrate hole pitch and avoid spreading or pinching the lead terminals at all costs. Case (2) When positioning with a holder or similar implement, take into consideration the tolerance of the holder, substrate and product dimensions so that pressure is not applied to the terminals. Note: Consider the thermal expansion coefficients of the materials used. Heat from preheating and soldering can cause the holder to expand and contract, which can put pressure on the leads, resulting in short-circuits. Case (3) When using a holder or other implement, the product and holder should be fixed in place at the terminal. Avoid methods that use pressure fitting or adhesive. More specifically, be careful of the soldering heat, which can cause the product or substrate to expand and contract, applying stress to the terminal. Please note that the resin used in the frame injection mold structure has a low melting temperature of to 13 C, making it susceptible to heat. Therefore, caution is required. ailures caused by overheating often occur due to aggressive preheating, high substrate temperature during preheating, or lengthy soldering process. Case (4) When performing automated mounting, bending of the substrate, cutting of the leads and/or clinching stress can conceivably damage the resin. In particular, caution should be observed when clinching or cutting the leads, since the amount of force applied during this time is significant. Therefore, test samples should be processed during the soldering phase and then evaluated for abnormalities/damage. Pressure fitting or adhesive Not Recommended Recommended Not Recommended Recommended Bending force applied after soldering. Case (1) Vertical stress applied after soldering. Cases (2), (3) 1

2 3. Solder Conditions The recommended conditions for soldering are as follows. Generally, because resin is used, the units are susceptible to heat. Therefore, the preheating and solder dip temperatures should be kept as low as possible. Item Conditions Solder Temperature Process Duration Solder dip At least 2mm from the base of the lead pin. Preheat temperature must be no greater than 8 C. No more than 26 C. 3 seconds or less 3 seconds or less Solder iron At least 2mm from the base of the lead pin. Power: No more than 3W. No more than 3 C. 3 seconds or less Reflow Reflow cannot be used. (other than the L-31 series) Please use a resin-based flux, since flux that is acidic or highly alkaline could cause corrosion. In addition, please refer to Page 12 for the recommended solder profile and pattern for solder dip units. 4. Washing Methods (1) Solvent Using the wrong chemical can damage the resin or surface of the case. Therefore, refer to the table below before washing. Chemical Name Ethyl alcohol Isopropyl alcohol Purified water to Use? Injection Mold Structure Damage may occur when using alternative washing solvents. or example, Azeotropic compounds contained in substitute freon can dissolve the hardening agents in the resin. Therefore, please implement the following methods and run sufficient checks for resin foaming or open circuits on a suitable sample size (n = 5 to ) before normal production. <Evaluation Method> a. High-temperature exposure after 3 seconds of immersion in a cleaning agent. b. Secondary soldering test after 3 seconds of immersion in a cleaning agent. (2) Washing Methods Washing Method Solvent wash Ultrasound wash to Use? Comments Room temperature immersion of less than one minute. Wash after confirming that no failures occurred during mounting tests. : : Requires verification 2

3 Surface Mount Unit Precautions The L-31 series was developed for surface-mount LED numeric displays requiring reflow soldering. When using surface mount units, please exercise caution with respect to the following. Storage The reliability of surface-mount products can be adversely affected during reflow soldering due to moisture absorption. or this reason, ROHM utilizes moisture-resistant packaging requiring usage under the following conditions. Storage conditions Storage temperature: 3 C Storage humidity: no greater than 7% RH Treatment after opening After opening, store at a temperature no higher than 3 C and a humidity no greater than 7% RH. Use within 72 hours. Baking (drying) process Baking is recommended (6 C±5 C, RH<2%, 24 hours min) should it be impossible to implement the above storage conditions and/or recommended treatment procedures. Please exercise care, since the reels and embossed tape can become misshapen during baking. Reflow Soldering Use sufficient caution with respect to the reflow conditions as the shape and/or size of the substrate as well as the type, quantity, mounting density and other aspects of the units will vary. Reflow is to be performed only once. Due to structural considerations, part of the terminal (tip) is not pre-plated. This leaves the base frame material (e or Ag) exposed, preventing formation of a solder fillet. Although this should not cause any problems regarding either the electrical characteristics or reliability, sufficient evaluation/checks should be carried out before usage. Please refer to Page 12 for surface mount solder profile and pattern examples. No solder plating No solder plating 3

4 Solder Profile and Pattern 1) Dip Types (LA, LB series) Please keep the preheat and peak temperatures with dip units as low as possible and the times as short as is feasible, since the products are susceptible to heat during flow soldering. As a guide, ensure that the internal temperature of the LED numeric display does not exceed C. Temperature C Preheat 3s or less Soldering Example 3s or less 26 C or less A single wave is better than a double wave, while stationary flow method is the best. After soldering, immediately lower the temperature of the substrate Conditions General flow conditions Solder Pattern Example LA-31 series Other series φ1.5 land shape φ.8 hole shape φ2. land shape Time (s) φ1. hole shape 2) Surface Mount Type (L-31 series) Please refer to the following reflow soldering profile and pattern examples for surface mount units. Substrate Surface Temperature ( C) Reflow Soldering Example C: Heat Slope 2 B: Preheat A: Heat Slope 1 D: Peak Temperature E: 2 C + range Time (s) Solder Pattern Example L-31 A/K series (1.4) P=1.27 Type L-31A/K series A (Heat Slope 1) 4 C/s max B (Preheat) 14 to 16 C (1 min. or less) C (Heat Slope 2) 4 C/s max. D (Peak temperature, peak time) 25 C max, 5s max. E (2 C + range) 5s max. 4

5 ailure Mechanisms Structural Diagram of rame Injection Mold Structure Number Item Lead frame Die bond LED chip Bonding wire Reflector Sealing resin Comments Iron, silver plate (terminal area: Sn-Ag-Cu plating) Ag + GaP or GaAsP on Gap or GaN or AlGalnP Gold Polymer resin ailure mechanisms caused by peeling 1. rame: Silver plating Wire : Gold The bonding strength is low because the materials differ. 2. Thermal stress can cause the resin to peel off the frame, since the adhesion strength is low between the frame and epoxy resin, and because the wire expansion coefficients differ. Wire rame 3. Since there is stress on the frame and the resin, there is stress on the wire. Due to the effects of 1, 2, and 3 above, the wire in breaks, resulting in lighting failure. Chip Pad: Gold Wire : Gold The material is the same, therefore the bonding strength is strong. Wire Chip Ag + 5 rame