Введение
Измерение восприимчивости устройства к повреждению влагой
Moisture sensitivity level (MSL) is a rating that shows a device's susceptibility to damage due to absorbed moisture when subjected to reflow soldering as defined in J STD 020. It relates to the packaging and handling precautions for some semiconductors. The MSL is an electronic standard for the time period in which a moisture sensitive device can be exposed to ambient room conditions (30 °C/85%RH at Level 1; 30 °C/60%RH at all other levels). Increasingly, semiconductors have been manufactured in smaller sizes. Components such as thin fine pitch devices and ball grid arrays could be damaged during SMT reflow when moisture trapped inside the component expands. The expansion of trapped moisture can result in internal separation (delamination) of the plastic from the die or lead frame, wire bond damage, die damage, and internal cracks. Most of this damage is not visible on the component surface. In extreme cases, cracks will extend to the component surface. In the most severe cases, the component will bulge and pop. This is known as the "popcorn" effect. This occurs when part temperature rises rapidly to a high maximum during the soldering (assembly) process. This does not occur when part temperature rises slowly and to a low maximum during a baking (preheating) process. Moisture sensitive devices are packaged in a moisture barrier antistatic bag with a desiccant and a moisture indicator card which is sealed. Moisture sensitivity levels are specified in technical standard IPC/JEDEC Moisture/reflow Sensitivity Classification for Nonhermetic Surface Mount Devices. The times indicate how long components can be outside of dry storage before they have to be baked to remove any absorbed moisture. MSL 6 – Mandatory bake before use
MSL 5A – 24 hours
MSL 5 – 48 hours
MSL 4 – 72 hours
MSL 3 – 168 hours
MSL 2A – 4 weeks
MSL 2 – 1 year
MSL 1 – Unlimited floor life
Уровень чувствительности к влаге (MSL) – это показатель, характеризующий восприимчивость устройства к повреждениям, вызванным поглощенной влагой при пайке методом рефлоу, как это определено в стандарте J STD 020. Он относится к требованиям к упаковке и обращению с некоторыми полупроводниками. MSL является электронным стандартом, определяющим период времени, в течение которого устройство, чувствительное к влаге, может подвергаться воздействию окружающей среды (30 °C/85% RH при уровне 1; 30 °C/60% RH при всех остальных уровнях). В последнее время полупроводники производятся во все меньших размерах. Компоненты, такие как устройства с мелким шагом и корпусы типа ball grid array, могут быть повреждены во время рефлоу SMT, когда влага, скопившаяся внутри компонента, расширяется. Расширение влаги может привести к внутреннему расслоению пластика от кристалла или выводов, повреждению проволочных соединений, повреждению кристалла и образованию внутренних трещин. Большая часть этих повреждений не видна на поверхности компонента. В крайних случаях трещины достигают поверхности компонента. В наиболее серьезных случаях компонент вздувается и лопается. Этот эффект известен как "эффект попкорна". Он возникает, когда температура компонента быстро повышается до высоких значений в процессе пайки (сборки). Это не происходит, когда температура компонента медленно повышается и достигает низких значений в процессе сушки (предварительного нагрева). Устройства, чувствительные к влаге, упаковываются в антистатический пакет с влагозащитным барьером, содержащий осушитель и индикаторную карту влажности, который герметично закрыт. Уровни чувствительности к влаге определены в техническом стандарте IPC/JEDEC "Классификация чувствительности к влаге/рефлоу для компонентов поверхностного монтажа негерметичного типа". Указанное время определяет, как долго компоненты могут находиться вне сухой упаковки, прежде чем их необходимо будет высушить для удаления поглощенной влаги.
Moisture sensitivity level (MSL) is a rating that shows a device's susceptibility to damage due to absorbed moisture when subjected to reflow soldering as defined in J STD 020. It relates to the packaging and handling precautions for some semiconductors. The MSL is an electronic standard for the time period in which a moisture sensitive device can be exposed to ambient room conditions (30 °C/85%RH at Level 1; 30 °C/60%RH at all other levels). Increasingly, semiconductors have been manufactured in smaller sizes. Components such as thin fine pitch devices and ball grid arrays could be damaged during SMT reflow when moisture trapped inside the component expands. The expansion of trapped moisture can result in internal separation (delamination) of the plastic from the die or lead frame, wire bond damage, die damage, and internal cracks. Most of this damage is not visible on the component surface. In extreme cases, cracks will extend to the component surface. In the most severe cases, the component will bulge and pop. This is known as the "popcorn" effect. This occurs when part temperature rises rapidly to a high maximum during the soldering (assembly) process. This does not occur when part temperature rises slowly and to a low maximum during a baking (preheating) process. Moisture sensitive devices are packaged in a moisture barrier antistatic bag with a desiccant and a moisture indicator card which is sealed. Moisture sensitivity levels are specified in technical standard IPC/JEDEC Moisture/reflow Sensitivity Classification for Nonhermetic Surface Mount Devices. The times indicate how long components can be outside of dry storage before they have to be baked to remove any absorbed moisture. MSL 6 – Mandatory bake before use
MSL 5A – 24 hours
MSL 5 – 48 hours
MSL 4 – 72 hours
MSL 3 – 168 hours
MSL 2A – 4 weeks
MSL 2 – 1 year
MSL 1 – Unlimited floor life
MSL 6 – Обязательная сушка перед использованием
MSL 5A – 24 часа
MSL 5 – 48 часов
MSL 4 – 72 часа
MSL 3 – 168 часов
MSL 2A – 4 недели
MSL 2 – 1 год
MSL 1 – Неограниченный срок хранения вне сухой упаковки
Moisture sensitivity level (MSL) is a rating that shows a device's susceptibility to damage due to absorbed moisture when subjected to reflow soldering as defined in J STD 020. It relates to the packaging and handling precautions for some semiconductors. The MSL is an electronic standard for the time period in which a moisture sensitive device can be exposed to ambient room conditions (30 °C/85%RH at Level 1; 30 °C/60%RH at all other levels). Increasingly, semiconductors have been manufactured in smaller sizes. Components such as thin fine pitch devices and ball grid arrays could be damaged during SMT reflow when moisture trapped inside the component expands. The expansion of trapped moisture can result in internal separation (delamination) of the plastic from the die or lead frame, wire bond damage, die damage, and internal cracks. Most of this damage is not visible on the component surface. In extreme cases, cracks will extend to the component surface. In the most severe cases, the component will bulge and pop. This is known as the "popcorn" effect. This occurs when part temperature rises rapidly to a high maximum during the soldering (assembly) process. This does not occur when part temperature rises slowly and to a low maximum during a baking (preheating) process. Moisture sensitive devices are packaged in a moisture barrier antistatic bag with a desiccant and a moisture indicator card which is sealed. Moisture sensitivity levels are specified in technical standard IPC/JEDEC Moisture/reflow Sensitivity Classification for Nonhermetic Surface Mount Devices. The times indicate how long components can be outside of dry storage before they have to be baked to remove any absorbed moisture. MSL 6 – Mandatory bake before use
MSL 5A – 24 hours
MSL 5 – 48 hours
MSL 4 – 72 hours
MSL 3 – 168 hours
MSL 2A – 4 weeks
MSL 2 – 1 year
MSL 1 – Unlimited floor life
Практичный
Компоненты, классифицированные по MSL, необходимо подвергнуть сушке перед сборкой, если время их воздействия превысило допустимое значение. После сборки чувствительность к влаге, как правило, перестает иметь значение.