CHLD - Cumulative Helium Leak Detection
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Frequently Asked QuestionsPernicka.com

Why CHLD?
The current standard for hermetic testing has been in use for more than 30 years! With manufacturing tolerances and liability requirements more stringent than ever, manufacturers can't afford to be derailed by tiny manufacturing flaws that drive operational failures and production downtime.

What are the benefits of CHLD?
•Does not use CFCs or other toxic or hazardous compounds.
•Safe to use on implantable medical devices - leaves no residues or toxic compounds.
•Can detect leakage of other gases or liquids contained inside a device.
•Combines fine-leak and gross-leak in a single, simple test for faster throughput

What is CHLD?
The process combines an ultra-high vacuum chamber with a programmable mass spectrometer to find, analyze and identify gases that escape from hermetic devices.

How does CHLD work?
CHLD is a closed system that accumulates all gases for analysis, making CHLD about 1,000 times more sensitive than the old leak detection method developed in the 1970s.

What size of leaks are we looking for?
Very small ones. Leak rates are typically measured in atmospheric cubic centimeters per second, usually abbreviated as atm-cc/sec. Hermetic packages must have leak rates that are one-billionth to one-trillionth of an atm-cc/sec. A typical car tire with a leak rate of one-billionth of an atm-cc/sec would go flat after about 500,000 years.

What's the smallest leak detectable by Pernicka Model 700H?
The CHLD process has a limit of leak detection more than 1000 times better than the old method, detecting leaks as small as 3 x 10-13 atm-cc/sec. The old fine-leak test has a limit of detection of about 5 x 10-10 atm-cc/sec.

Has CHLD been accepted in the industry?
DSCC (Defense Supply Center Columbus) has approved and published the Cumulative Helium Leak Detection (CHLD) method - revised MIL-STD 750 for determining hermeticity of semiconductor packages and implantable electronic devices - pioneered and developed by the Pernicka Corporation. CHLD is currently in use in applications for NASA and the US Food and Drug Administration (FDA).

What types of devices are tested by Pernicka's CHLD system?
The CHLD process and the Pernicka Model 700H can be used to test objects of virtually any shape, size, or material.

Who would typically require CHLD?
The quality assurance (QA) departments of companies that make implantable medical devices, semiconductors or electronic modules in satellites where extension of device operational life is mission-critical:

1) Implantable medical devices:
Implantable medical devices are exposed to more moisture than most other electronic devices. Reliability can be compromised if moisture is allowed into the device, or any toxic compound leaks out.

2) Electronic modules used in satellites and similar applications:
The high cost of launch is driving design specifications for longer satellite operational life. Satellite electronics must also be able to survive the manufacturing and testing process on earth prior to launch.

3) Extremely small IC packages:
Growing miniaturization of modern packages, including 'UB' packages, does not allow reliable testing using the old test standard given the potential for tiny leaks.

Why is Helium used in leak detection?
The Pernicka Model 700H uses a mass spectrometer to profile the contents of the vacuum chamber as it is evacuated. The Pernicka Model 700H uses helium gas to detect leaks given that helium is inert and non-toxic. It's common availability allows helium to readily pass through materials that other molecules cannot.

Who are Pernicka's competitors?
No one offers a CHLD test machine today. The Pernicka Model 700H is the first commercially-available CHLD system.

Is the Model 700H available?
Yes. The Pernicka Model 700H is now shipping and in use at leading medical device and high-rel facilities. Please contact us if you would like to see the system in action at one of several commercial demonstration sites. Please contact info@chldpernicka.com for details.