On July 1st, Toshiba Corporation's Semiconductor Company and Storage Products Company consolidated to form Semiconductor & Storage Products Company.This page describes reliability information of semiconductor products.

Temperature and Humidity

[As of April, 2011]

Moisture Resistance Tests

Most semiconductors devices of recent years are encapsulated in plastic resin. The reliability of these devices largely depends on the moisture resistance of the package. Various types of moisture resistance evaluations tests have been developed in order to evaluate these devices quickly. Table 1 shows examples of these moisture resistance evaluation tests.
The tests are largely divided into two groups. The first group places the device in a humid atmosphere, and the second group applies bias to the device while subjecting it to humidity or after moisture has penetrated into the device. The device classification is made according to the device type (such as the level of power consumption) and the type of failure mechanism to be detected.
If the acceleration rate is too fast, humidity resistance testing can produce failure modes that are different from those that appear during actual usage or problems related to test reproducibility may arise. Therefore, extra care must be taken when performing these tests. Particularly with saturated type PCTs (pressure cooker tests), unexpected failure modes that will never occur in the field (for example, pin-to-pin migration on outer leads) can occur because the device may be exposed to conditions in which dew is formed. Consequently, care must be taken when performing assessments or when evaluating test results.
In addition, recently the mainstream semiconductor device has become the surface mounted device (SMD), accelerating compact and thin designs one step further. With these types of semiconductor devices, the thermal stress during mounting and resin humidity absorption during storage cannot be ignored. To properly simulate actual usage conditions, the mounting stress is applied as part of a pretreatment process, and a humidity resistance test is conducted.

Table 1 Main Moisture Resistance Evaluation Test Methods
Test			Example Conditions
Storage Test	High temperature high humidity storage test		85°C/85% RH 60°C/90% RH
	Pressure cooker test (or called Unbiased autoclave test)	Saturation type	121°C/100% RH1 27°C/100% RH
	Pressure cooker test (or called Unbiased autoclave test)	Non-saturation type	120°C/85% RH 130°C/85% RH
Biased Test	High temperature high humidity biased test		85°C/85% RH Biasing applied
	High acceleration stress test		130°C/85% RH Biasing applied
	Pressure cooker test, high temperature biased test (compound stress test)		121°C, 203kPa (20h) → Leave at room temperature (2h) → high temperature biased test (20h) : consist of 1 cycle.

Moisture Resistance Acceleration Model

There have been a number of reports of accelerated models for estimating the reliability of plastic-encapsulated semiconductor devices based on humidity resistance test data. The model described in this section is the absolute water vapor pressure model^{Note 1}. The relationship between lifetime and absolute water vapor pressure in the absolute water vapor pressure model2 is expressed by the equation below. The acceleration coefficient n is approximately 2.0 according to experimental data.

L: Moisture resistance lifetime (h)
V_p: Absolute water vapor pressure (Pa)
N: Accelerated coefficient
A: Experimental constant

This is [Figure 1 Example of Relationship Between Absolute Water Vapor Pressure and Moisture-Resistance Lifetime].

Figure 1 Example of Relationship Between Absolute Water Vapor Pressure and Moisture-Resistance Lifetime

This is [Figure 2 Example of Relationship Between Applied Voltage and Lifetime for Humidity and Resistance Test].

Figure 2 Example of Relationship Between Applied Voltage and Lifetime for Humidity and Resistance Test

Fig. 2 shows an example of the relationship between applied voltage and lifetime in a humidity resistance test.
Moisture-resistance lifetime in the field can be estimated from acceleration test results by taking into consideration temperature, relative humidity and applied voltage conditions as well as the failure mechanism.

Note 1: Bibliography. J. L. Flood; "Reliability Aspects of Plastic Encapsulated Integrated Circuits," 10th IRPS (1972)