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3.4.1 NEC Electronic's concept
of recommended soldering conditions |
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3.4.2 Setting method | |
3.4.3 Classifications |
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3.4.4 Description method | |
3.4.5 Symbol definitions |
| 3.4.2 Setting method |
| An example of the heat resistance test used to set the recommended soldering conditions is shown below. |
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| Figure 3-24. Example of heat resistance Test |
| ( Preprocess ) 1. Initialization In order to remove the moisture from the samples to be evaluated, initialization took place at 125°C and for a specified time. 2. Moisture absorption preprocess · The standard for products that do not require moisture absorption control is equivalent to saturated moisture absorption at 30°C, 85% RH (on the assumption that the products are used in a hot and humid region). However, since moisture absorption at 30°C, 85% RH takes a long time, the actual test is conducted under accelerated conditions of 85°C, 85% RH (note that the moisture absorption time differs depending on the thickness of the package and other factors). · The standard for products that require moisture absorption control is 30°C, 70% RH (note that the moisture absorption time differs depending on the products). |
| ( Heat application
) A product's heat resistance is evaluated by imposing thermal stress using any of the soldering methods listed above. If the soldering method is infrared reflow, the thermal stress is imposed one, two, or three times based on the temperature profile shown in (1), (2), and (3) in 3.4.3 below. Wave soldering is performed under the conditions shown in (5) in 3.4.3 below. |
| ( Test ) · NEC Electronics basically conducts the high-temperature high-humidity bias, pressure cooker, and temperature cycle tests described above to check the reliability of the product after it has been reflow soldered. The product is also checked for package cracks and peeling. The recommended conditions are determined from the results of the above tests. · The testing time of some products may be 192 hours or less in the case of the pressure cooker test. Moreover, the pressure cooker test is conducted as a reference test for some products. · The conditions in the temperature cycle test may range from -55°C to +125°C. |
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