What causes DVDs to break?

Introduction: The "lifespan of DVDs" - when precious memories disappear

Wedding footage, children's growth records, rare movie collections—many people store their precious memories on DVDs. However, they may suddenly encounter problems such as "playback failure" or "image distortion." In fact, there are three main causes of DVD damage: physical factors, chemical degradation, and environmental influences. This article provides a scientific explanation of how DVDs break down and introduces practical preventative measures for long-term data storage.

Physical damage: disc structure and fatal "scratch depth"

DVDs have a four-layer structure : the outermost "protective layer" (approximately 1.2 mm thick), the "recording layer" where data is recorded, the "aluminum reflective layer" that ensures reflectivity, and the underlying "polycarbonate substrate." If this structure is destroyed by external force, the data becomes unreadable.

1. Types of scars and their effects

• Shallow scratches (less than 0.1 μm deep) : If only the protective layer is scratched, the DVD player's error correction function can repair the damage, but repeated playback increases the risk of read errors.
• Deep scratches (0.1 μm or more) : If they reach the recording layer or reflective layer, the laser light will not be reflected properly, causing the image to skip or freeze. Scratches on the inner circumference (where data density is high) are particularly fatal.

For example , in the case of home use, cracks of 5mm or more in diameter are often caused by children dropping DVDs on the floor or scraping the edges when taking them out of the case. According to a survey by JVC, physical damage accounts for 62% of all DVDs that cannot be played.

2. Bending and cracking

Although the polycarbonate substrate of a DVD is flexible, repeated bending or deformation in a high-temperature environment can cause delamination. In particular, if the DVD is left on a car dashboard, the substrate will bend at high temperatures (over 60°C) in the summer, making it more susceptible to reading errors.

Chemical Deterioration: Invisible Corrosion Progression

1. Oxidation of the aluminum reflective layer (Disc Rot)

The aluminum used in the reflective layer of DVDs reacts with moisture and oxygen to form aluminum oxide , which reduces reflectivity and ultimately makes the data unreadable. This phenomenon is called "disc rot" and is particularly prevalent on self-recordable DVDs (DVD-R/RW).

Scientific analysis : The thickness of the aluminum layer is approximately 50 nm (1 nm = 1 billionth of a meter). As oxidation progresses, the reflectivity drops to 70% or less of its initial value, and when the PIE (parity inner error) exceeds 280, the disc is deemed unplayable (JIS X 6257 standard).

2. Mechanism of delamination

DVDs are made up of multiple layers bonded together with adhesive, but poor quality adhesive or humidity can cause the layers to separate. Salt-containing humidity, especially in seaside areas, can degrade the adhesive, causing parts of the disc to "float." This can cause the laser beam to lose focus, resulting in "block errors" during playback.

Environmental factors: "Invisible damage" caused by temperature, humidity, and light

1. Temperature and humidity impact data

According to JIS Z 6017 (standard for long-term storage of electronic image documents), the optimal storage environment for DVDs is a temperature of 15-25°C and a humidity of 40-60% . Any deviation from these limits will significantly accelerate the rate of deterioration.

• High temperatures and humidity (above 30°C, humidity above 70%) : The oxidation rate of the aluminum reflective layer is three times faster than at room temperature, and the disc may become unusable within five years.
• Low temperatures (below 0°C) : Polycarbonate substrates become brittle and prone to cracking.

2. The threat of ultraviolet rays

Ultraviolet rays from sunlight and fluorescent lights break down the dyes in the recording layer. In particular, DVD-R discs, which use phthalocyanine dyes, lose their light absorption ability when exposed to UV light for extended periods, resulting in poor data readability. Research by the Library of Congress has confirmed that exposure to direct sunlight can reduce the lifespan of DVDs to less than 10 years.

Preventive measures: "Long-term preservation strategy" based on JIS standards

1. Optimizing storage methods

• Vertical storage : Store boards vertically in a dedicated rack and do not stack them. Horizontal storage will cause distortion of the boards.
• Use a moisture-proof case : Store in an airtight case filled with silica gel to maintain a humidity level of 40-60%.
• Cleaning tips : To remove dirt and fingerprints, wipe in a straight line from the center to the periphery with a microfiber cloth. Do not use alcohol-based cleaners.

2. Implementing JIS Z 6017

JIS Z 6017 recommends "regular data migration" and "multiple backups" for long-term storage of electronic data. Specifically:

• Copy your data onto a new DVD every five years.
• Make two or more backups of important data and store them in different locations.

3. Selecting High-Quality Media

Archival DVDs (e.g., JVC's "ISO Archival DVD-R") use phthalocyanine dyes and a gold alloy reflective layer, and have a lifespan of over 200 years in accelerated aging tests. While more expensive than standard DVDs, they are a worthwhile investment for preserving your precious memories.

Summary: Three Key Points to Make DVDs Last Longer

The main causes of DVD damage are physical damage, chemical degradation, and environmental factors. To prevent these:

1. Handling precautions : Avoid fingerprints and do not drop.
2. Environmental management : Maintain appropriate temperature and humidity levels and block ultraviolet rays.
3. Regular maintenance : cleaning and backing up are essential.

To protect your important data, why not consider reconsidering your storage environment now? Aestiquo offers portable DVD players and archiving accessories. Please take a look.