ESD: Protecting ESDS Components

ESD: Protecting ESDS Components

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Protecting ESD Sensitive (ESDS) Components

Semiconductor manufacturers take every possible measure to ensure their components arrive to you in excellent shape, free from any kind of defects. A good deal of the effort goes to the packaging made to ensure that components are protected from all kinds of ESD attack during transport.

The following series of photos will help you appreciate the effort the manufacturer does to protect your IC (and similar sensitive devices). Exampled here is an IC sample shipped by Zilog.

	Figure 3. An IC sample arrives at e-Gizmo from Zilog. Although hand delivered, Zilog did not assume that it will be handled with fanatic care during transport, hence, wrapped the samples in pink¹ antistatic bubble bag. The bubble bag will keep the content undamaged even if the bag is thrown like a soccer ball.
	Figure 4. Out of the bubble bag, the ICs are pack inside static shielding bag. The shielding bag is the main ESD protection. This bag prevents any static charge from reaching the ICs inside. The bag is vacuum sealed to keep air from contaminating the component pins, preserving solderability². The white shielding bag (left) contains IC that demands more protection against pin contamination.

Figure 5.

Opening the shielding bag reveals the IC safely tucked inside an antistatic tube. Without the shielding bag, the IC is already partially exposed to ESD threat. The antistatic tube does not allow static charge to build up and helps prevent direct contact to ESD potentials, but strong discharge occurring outside the tube can pass through it. Hence, it can only provide limited protection to the IC inside. Inside the white shielding bag, the IC is packed with moisture absorbing material and a humidity indicator label that will report if there was a moment the moisture exceeded an acceptable level.

Figure 5.

The moment the IC leaves the comfort of the antistatic tube, it will be helpless against any ESD attack. Now it will depend entirely to you to keep it safe from such threat.

ICs in the Hands of a Retailer

Component ESD protection effort starts to break down at the hands of uninformed retailers. Lacking ESD awareness, we could not expect these retailers to take proper measures to protect the components during handling. Pictured below is one disturbing yet very common practice telling us the kind of ESD abuse the IC might have suffered while in the hands of a retailer.

Figure 6. A static sensitive IC wrapped in a plastic polybag is as good as dead. A plastic polybag is a very efficient static generator and is one of the worst places you can place an IC in. The IC may still be working, but some irreversible damage may have probably occurred.

Put in mind, however, that comprehensive ESD protection is an expensive business, no retailer can afford ESD protection for an individual IC to the same level of protection as that of the IC manufacturer. ESD aware retailers provide protection in varying ways. Some examples are shown in the figure 7 and 8.

Figure 7. At e-Gizmo, reasonable level of ESD protection is provided by putting sensitive ICs and devices inside a small shielding bag.

Figure 8. Alexan Commercial (no relation with e-Gizmo) ESD protects their ICs by wrapping the IC pins with small piece of aluminum foil.

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Note 1: Static safe plastic packing materials are easily identified by their pink color.

Note 2: Solderability is a big issue for machine soldered PCB assemblies. Anything that affects negatively soldering consistency is a serious quality problem.

03/24/2007

Last Update

Page 3 of 5 pages

Rev A

Initial Release

Written By:

Henry L. Chua

comments?

hlc@e-gizmo.com

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