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Memory tester

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Memory testers are specialized test equipment used to test and verify memory modules typically in SIMM or DIMM configurations. It detects functional failures of memory modules.

Types

Memory module testers can be broadly categorized into two types, hardware memory testers and software diagnostic programs that run in a PC environment. Hardware memory testers have more sophisticated and comprehensive test features built into the tester as compared to software diagnostic testing program. Software diagnostic does allow for detection of possible problems when memory modules are already installed on the computer system.

Hardware testers

High-end automatic test equipment (ATE) Class Memory testers are used by most OEM memory chip manufacturers such as Samsung, Hyundai, Micron…etc. They are typically priced starting at one million dollars per system. This equipment must be operated by well trained semiconductor engineers. ATE Class Memory testers are built with very complex test algorithms to detect memory faults during the final stages of memory chip packaging.

Mid-range memory testers typically priced under $26,000,[1] and are commonly found in memory module manufacturing assembly houses. These testers are built to support mass volumes of memory module testing. They are also used for detecting assembly faults caused by mis-soldering and cross-cell contamination after chips are assembled onto PCB or SIMM cards. These memory testers are usually docked onto an automatic handling system for high volume production testing, thus eliminating manual intervention by an operator.

Low-end memory testers (e.g.,[RAM Stress Test][2]) are usually relatively low cost ranging from $700 – $1,300[3]. RAM Stress Test identifies memory defects that may have passed every usual manufacturing ATE test, but which can still fail in normal use. A major advantage of RAM Stress Test compared to ATE, is the capability of testing and validating RAM within the complete system environment (CPU, Memory, Motherboard, Power Supply), testing for Behavioral failures that are sensitive to system idiosyncrasy. .

Software testers

Memory diagnostic software programs (e.g., Memtest86, RAM Stress Test) are relatively low cost ranging from $700 – $1,300[4]. RAM Stress Test identifies memory defects that may have passed every usual manufacturing ATE test, but which can still fail in normal use. A major advantage of RAM Stress Test compared to ATE, is the capability of testing and validating RAM within the complete system environment (CPU, Memory, Motherboard, Power Supply), testing for Behavioral failures that are sensitive to system idiosyncrasy.

Memory diagnostic software programs (e.g., Memtest86, QuickTech[5]) are relatively low cost ranging from $49[6] – $299[7]are used to check for memory defects on a PC. They are usually in the form of a bootable software distribution (floppy, cdrom, usb or network pxe boot). Memory test tools do not utilize an operating system allowing for the full memory address range to be available for testing. Memory diagnostic software cannot be used when a PC is unable to complete the Power-on_self-test. Test results usually save to a storage device (e.g., floppy disc, usb) or COM/LPT printer, however it is common practice that a working display is required.

Detected faults

Memory testers are designed to detect two types of faults that affect the functional behavior of a system ( memory chip, logic chips or PCB board). They are

  • Non-Permanent faults
  • Permanent faults

Non-Permanent faults occur at random moments. They affect a system's behavior for an unspecified period of time. The detection and localization of non-permanent faults are extremely difficult with a memory tester. Sometimes non-permanent faults will not affect the system's operation during testing.

There are two types of non-permanent faults :

  • Transient fault
  • Intermittent fault

Transient faults are hard to detect, and there are no well defined faults to detect. Errors in RAM introduced by transient faults are often called software errors, the following examples are possible factors that will contribute to transient faults :

Intermittent faults are caused by non-environmental conditions such as:

  • Loose connections
  • Deteriorating or aging components
  • Critical Timing
  • Resistance and capacitance variation
  • Physical irregularities
  • Noise (noise disturbs signals in the system)

Permanent faults affect the logic values in the system permanently, these faults are easier to detect using a memory tester. Examples include:

  • Incorrect connections between integrated circuits, boards….etc. (e.g. missing connections or shorts due to solder splashes or design fault)
  • Broken component or parts of components
  • Incorrect IC Mask, (Manufacturing problem)
  • Functional design errors (logical function that had to be implemented, is designed incorrectly).

See also

References

  1. ^ http://www.pcstats.com/articleview.cfm?articleID=1174
  2. ^ https://www.uxd.com/ram-stress-test.html
  3. ^ http://shop.uxd.com/category-s/110.htm
  4. ^ http://shop.uxd.com/category-s/110.htm
  5. ^ https://www.uxd.com/quicktech-premium.html
  6. ^ http://memtest86.com/sales/index.php
  7. ^ http://shop.uxd.com/quicktech-self-boot-diagnostics-p/qtc1usb.htm
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