Quality Standards and Environmental Certifications

Handling, Storage, and Shelf Life of Semiconductor Devices

Handling, Storage, and Shelf Life of Semiconductor Devices

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By Bradley Smith,
Allegro MicroSystems, LLC

介绍

Electronic devices are available in many package types and can contain semiconductors (integrated circuits), magnets, capacitors, and resistors. This application note provides guidelines for the handling and storage of Allegro devices with regards to functionality and shelf life. Precautions against ESD (electrostatic discharge), moisture, and contaminants need to be considered for electronic devices.

在处理、保质期和储存条件方面，电子设备可能存在几个方面的问题：

  • Handling considerations involve ESD and environmental protections.
  • Shelf-life considerations involve solderability, MSL, and open-bag floor-life conditions.
  • Storage considerations involve proper bagging and environment.

Applicable Documents

下列文件提供了进一步的背景资料和指导，是必读文件。在每个文件中都列出了必须引用的适用文件。

我nternational standards:

  • Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices, IPC/JEDEC J-STD-020D.1
  • 潮湿/回流敏感表面贴装设备的处理、包装、运输和使用, IPC/JEDEC J-STD- 033C
  • Requirements for Handling Electrostatic-Discharge-Sensitive (ESDS) Devices，杰德克JESD625

Allegro application notes:

Handling

Allegro产品通常装在密封袋中运输，其中包含磁带和卷盘产品、装在运输管中的装置或圆片罐。这些运输材料抗静电，也可以导电，这取决于产品和配置。客户必须充分了解并充分执行JEDEC JESD625（处理静电放电敏感（ESDS）设备的要求）中详述的ESD预防措施。这包括根据客户来料检验、装配线工位、成品检验和包装区域的配置需要，强制使用ESD手套、接地和ESD保护的台面以及定向空气电离器。

When using tape-and-reel packaged devices, the cover tape should be removed at a rate of 10 mm/s or less and at an angle of 165 to 180 degrees from the carrier-base plastic in order to minimize ESD generation.

Other environmental protections should be used. The protection of product in shipping bags, and after the opening of these bags, should prevent contamination by the ambient environment from dust, corrosive materials, humidity/water, or other chemicals (containing chlorine or phosphates). Specifically, electronic devices should not be handled with bare hands, or exposed to unmasked personnel. Although finger cots can be used, it is important to ensure their proper use and immediate replacement if contaminated (i.e. use sterile technique to prevent transfer contamination from one surface to another). Gloves are a better choice to prevent contamination.

Face masks to prevent spittle and discharge from talking should be used. Smocks or gowns should be used as well. Finally, protective footwear is desirable to maintain a clean work environment.

Note that Allegro uses fully gowned personnel—from head to foot, including full head covering, eye shields, face mask, gloves, full suit, and booties—in all areas of assembly, from start to finish, in a clean-room-class environment. Therefore, customer-returned parts with corrosion may be from the customer’s assembly or the end application, as determined by Allegro failure analysis. See Allegro application note,Chemical Exposure of Devices, for details.

Shelf Life and Floor Life

Surface-Mount Devices (SMD) and Moisture Sensitivity Level (MSL)

SMD产品对封装的模塑料内的湿气敏感，并且在经历板焊料回流时，模塑料和引线框架之间可能发生分层。MSL分类（J-STD-020D.1）给出了回流温度为260时，从MSL 1到MSL 3的每种SMD封装类型的额定值°C或更低的温度（如装运箱上的警告标签所示）。MSL 1分类意味着包装非常坚固，在回流时不易受水分影响；因此，MSL 1的“地板寿命”（部件暴露于环境温度和湿度的时间）是无限的(≤30°C/85%相对湿度）。对于MSL 2零件，地板寿命为1年≤30°C/60%相对湿度和MSL 3为168小时（7天），温度为≤30°C/60%相对湿度。

客户只需了解有关地板寿命的MSL 3设备。例如，如果客户仅使用额定MSL 3的部分卷绕产品，而剩余产品暴露在环境温度和湿度下，则必须参考J-STD-033C中的地板寿命表7-1，以确定零件的实际地板寿命。因此，在30°如果回流温度为260℃，C/60%RH持续7天是最大地板寿命°C（J-STD-033C中的所有表格均基于260°C回流，如MSL分类，除非Allegro另有说明）。如果回流温度为245°C、 最大楼层要大得多，并且可能是无限的（目前没有所有设备的数据可用）。如果曝光量小于30°C/60%RH，回流温度为260°C、 那么地板寿命就大得多，在50%相对湿度下是无限的。大多数客户使用的回流温度为230℃°C至245°C（最大值），环境为25°C和60%至70%相对湿度，因此无需担心MSL 3设备的地板寿命。

Note that through-hole devices and devices which will be welded, crimped, or hand-soldered are exempt from MSL considerations, because the package body does not exceed the reflow profile temperatures found in board soldering.

可焊性和长期储存

  • 在长期储存后，部件的可焊性，例如替换零件库存或“上次购买”零件，是一些客户所面临的问题。
  • Parts are supplied in moisture-barrier bags (MBB) for parts labeled as MSL 2 or MSL 3 and contain desiccant (optional with MSL 1 devices). The MBB offer protection of the units from environmental factors. While this is recommended for parts that are to be reflow-soldered to prevent “popcorn” delamination within the package body, the solderability of the leads is not affected.
  • Allegro parts have their terminations plated with 100% tin or nickel-palladium-gold (NiPdAu).
  • 100%的废料部分受到轻微的水平of oxidation from exposure to humidity and temperature. The levels of oxidation accumulated from such exposure does not affect the solderability quality of the parts, as seen by Allegro standard testing procedure of preconditioning parts for 8 hours with a steam chamber and wetting balance testing, as shown below. See Allegro application note,Soldering Methods for Allegro Products (SMD and Through-Hole), for more information. The study below shows that tin plating is good for 10 years storage at ambient.

A solderability study was done with parts stored openly in a drawer at ambient conditions for up to 10 years. Included were samples that were preconditioned with 8 hour steam. All parts soldered very well. This shows that long-term storage at ambient conditions does not affect solderability and therefore storage in a sealed bag is more than adequate.

  • 这些润湿平衡曲线显示了浸入SAC 305合金时，在SG封装零件上使用0.5%轻度活化焊剂（带集成背偏磁铁的4针SIP封装）的润湿力与时间的关系。浸泡3秒后，所有试样均表现出良好的最终润湿力（大于0.1mN/mm）。
  • The top three curves are on virgin units stored exposed to ambient conditions for 5, 6, and 10 years, respectively. The bottom three curves are on 8 hour steam-aged units stored exposed to ambient conditions for 4, 9, and 10 years, respectively.
  • NiPdAu零件引线上的金涂层可防止引线在湿度和温度的环境暴露下发生任何氧化或退化，因此保质期是无限的，不需要特别的预防措施。

Figure 1

Storage Life

All Allegro packages, whether SMD or not, have a minimum shelf life of 5 years.

对于未开封的包装袋，用带干燥剂的密封MBB包装，SMD的保质期对于MSL 3零件大于5年，对于MSL 1和MSL 2零件不受限制。这假设MBB保持完整；因此，建议采用双层包装，以便长期储存。请注意，MSL 1零件实际上不需要MBB，但建议长期存放。

As previously noted, solderability is not affected by storage up to 10 years.

Storage of die or wafers also exceeds 5 years in MBB and double-bagging is recommended for longer than 5 year storage. Recommended ambient storage conditions are usually <25°C and <60% RH.