5.Size 2220,1206,1210,1812. SMD Chip Ceramic Capacitor Distributor Murata of –Circuit Ocean.
2. Correction with Spot Heater Compared to local heating with a soldering iron, hot air heating by a spot heater heats the overall component and board, therefore, it tends to lessen the thermal shock. In the case of a high density mounted board, a spot heater can also prevent concerns of the soldering iron making direct contact with the component. 2-1. If the distance from the hot air outlet of the spot heater to the component is too close, cracks may occur due to thermal shock. To prevent this problem, follow the conditions shown in Table 4.
2-2. In order to create an appropriate solder fillet shape, it is recommended that hot air be applied at the angle shown in Figure 1.
3. Optimum solder amount when re-working with a soldering iron 3-1. If the solder amount is excessive, the risk of cracking is higher during board bending or any other stressful condition. Too little solder amount results in a lack of adhesive strength on the termination, which may result in chips breaking loose from the PCB. Please confirm that solder has been applied smoothly and rising to the end surface of the chip.
3-2. A soldering iron with a tip of ø3mm or smaller should be used. It is also necessary to keep the soldering iron from touching the components during the re-work. 3-3. Solder wire with ø0.5mm or smaller is required for soldering. 4. For the shape of the soldering iron tip, refer to the figure on the right. Regarding the type of solder, use a wire diameter of ø0.5mm or less (rosin core wire solder). 4-1. How to Apply the Soldering Iron Apply the tip of the soldering iron against the lower end of the metal terminal. 1) In order to prevent cracking caused by sudden heating of the ceramic device, do not touch the ceramic base directly. 2) In order to prevent deviations and dislocating of the chip, do not touch the junction of the chip and the metal terminal, and the metal portion on the outside directly. 4-2. Appropriate Amount of Solder The amount of solder for corrections by soldering iron, should be lower than the height of the lower side of the chip.
5. Washing Excessive ultrasonic oscillation during cleaning can cause the PCBs to resonate, resulting in cracked chips or broken solder joints. Take note not to vibrate PCBs
6. Electrical Test on Printed Circuit Board 1. Confirm position of the support pin or specific jig, when inspecting the electrical performance of a capacitor after mounting on the printed circuit board. 1-1. Avoid bending the printed circuit board by the pressure of a test-probe, etc. The thrusting force of the test probe can flex the PCB, resulting in cracked chips or open solder joints. Provide support pins on the back side of the PCB to prevent warping or flexing. Install support pins as close to the test-probe as possible. 1-2. Avoid vibration of the board by shock when a test-probe contacts a printed circuit board.
7. Printed Circuit Board Cropping 1. After mounting a capacitor on a printed circuit board, do not apply any stress to the capacitor that causes bending or twisting the board. 1-1. In cropping the board, the stress as shown at right may cause the capacitor to crack. Cracked capacitors may cause deterioration of the insulation resistance, and result in a short. Avoid this type of stress to a capacitor.