On "Three Preventions" Packaging of Military Electronic Equipment (I)

Overview

The current status of "three defenses" packaging for military electronic equipment, analyzes the problems in packaging design, material use, "three defenses" technology, and "three defenses" tests, and puts forward proposals for standardization of "three defenses" packaging.

Foreword

In modern warfare, electronic devices increasingly show their combat effectiveness and advancement. In order to ensure that the military electronic equipment is used in various environments with higher reliability, in addition to the quality of the equipment itself, packaging technology and quality are critical factors. Especially in terms of moisture, mold, and corrosion protection. Through investigation, we found that because of the backward packaging technology, the “three defenses” performance was not successful, and the product appeared to be corrosive and moldy when it was unpacked. Some components have an opening qualification rate of less than 10%, and the product performance and service life are affected. Even if they are not used, they will be scrapped. This is not only detrimental to equipment reliability or even failure in a harsh and urgent wartime environment, resulting in delays in fighter planes, and it is distressing for the state to suffer a huge loss of about 10 billion yuan per year. It can be seen that it is imminent to improve and update the "three defenses" packaging technology. To this end, only a brief overview of some of the current understanding of the packaging of electronic products.

I. Status and Problems of "Three Preventions" Packaging

In recent years, China's military packaging has made progress in relying on technological progress and developing the packaging industry. However, it is worrying that there are many problems in the "three defenses" packaging design and the adoption of new materials and new processes. Need full attention.

1. Packaging design is part of the overall product design

A factory produces military radars, which are delivered to packaging workshops after completion of the product. As the military has to deal with anti-vibration requirements for the packaging, it will carry out the test of the sports car on the third-level highway. After the test, the equipment failed and repairs and packaging were improved. Then again test → fault → repair → improvement. Repeat this cycle several times before leaving the factory. Although the manufacturer is responsible for the product, the product has undergone many tests and repairs. Due to the small production volume, equipment that is still delivered to the troops after refurbishment will inevitably have hidden dangers left after the destructive test.

We think that such packaging is not satisfactory. Packaging design is a part of the overall design of the product. If the shock-proof and impact-resistant packaging is considered in the initial design of the product, factors such as packaging environment, seismic resistance, and protection materials are designed to greatly reduce manpower, material resources, and time. The waste increases the reliability of the package. Product packaging design must not wait until the product is manufactured before it is considered or rushed to conduct part of the test, ie delivery. During the investigation, it was found that the manufacturer focused on the test of the mechanical environmental performance of the package and regarded the climatic and environmental suitability test. The pros and cons of mechanical environmental performance can be found in the process of transportation, handling, and transit. This is a short-term effect. The adaptability of the climate and environment requires that the packaging be subjected to changes in the temperature and humidity of the environment during long storage periods. It is exposed to moisture, mildew, and corrosion. This is a long-term effect. The short-term effect is obviously obvious and it is also one of the reasons why producers and users do not pay attention to the “three defenses” test. Many manufacturers test the product's packaging according to the standards of the road grade and specified distance of the transportation tools (as in the above example), test the shockproof and shockproof performance of the package, and rarely carry out "three defense" tests, especially large scale product. Therefore, it is necessary to formulate a unified "three defenses" packaging test method and standard, and at the same time carry out research on the "three defenses" measures of products, in order to comprehensively improve the quality of packaging. This example illustrates:

(1) The overall design of the product does not include packaging design. The packaging work cannot receive due attention.
(2) Packaging design is often focused on tests such as vibration, impact, and other direct damage, and insufficient attention is paid to indirect slow damage. Therefore, the “three defenses” performance of packaging is often overlooked.

2. "Three defenses" packaging is the organic composition of product packaging

Some manufacturers have excessively emphasized some direct damage factors in the environment for the purpose of improving the quality of product packaging, or improper selection of certain technological measures, which will affect other protective functions. Ignoring the packaging as a whole, every protective measure must comply with the overall requirements and must not hinder the overall cooperation. However, for indirect damage that is not obvious in the short term, blindly cite the use of various protection techniques that are already mature in the use of products, and hope to obtain satisfactory results. However, contrary to expectations, they often get opposite results. Due to the adoption of various measures, some of the measures are in conflict with each other, and sometimes have adverse effects. Sometimes, the adopted process may not achieve the desired results. For example, the oxygen-free packaging used in the inner package may have been used for corrosion inhibition and mildew prevention. The role of anti-mildew treatment in the package, the process is repeated. Because of the improper selection of anti-mold agents, the adverse effects of metal corrosion are caused. Nitrogen filling packaging can theoretically play the role of anti-mildew, but according to the current domestic response, nitrogen-filled packaging is technically problematic and does not meet the requirements for anti-mildew. Some manufacturers in the packaging due to the lack of a unified study, at the same time there is no complete research data can learn from, just want to use some more "new technology", but can not get satisfactory results.

Based on the above, we believe that the research of the packaging process lacks complete and in-depth research and cannot provide system data to guide production and avoid the errors that occur when certain processes are used. Some corrosion-inhibiting volatilization mildew-repellent agents can receive double-layer effects when combined with silica gel. Therefore, when using several technological measures, the mutual interference between the processes and mutual promotion needs further study. Strengthening the basic research of the process is a prerequisite for ensuring the quality of the process, and there should be specialized units specializing in this area.

2. Adoption of new packaging materials and elimination of used packaging materials

The packaging must be moisture-proof, mildew-proof and corrosion-proof. The inner packaging material must have low moisture permeability and air permeability. In general, the basic materials for sealing packaging are mainly plastic films. These materials include not only single-layer films, but also various plastic/plastic composite films and plastic/aluminum/plastic composite films. At present, the plastic/aluminum/plastic composite membrane has the best oxygen and moisture resistance (oxygen, water vapor transmission is almost zero), but it is expensive and difficult to popularize. Therefore, most of the packaging materials currently used for sealed packaging are inexpensive plastic/plastic composite films.

Polyvinyl chloride films have proven to be corrosive to metals and are not allowed to be used as encapsulation materials for electronic products. However, there are still many military factories still in use because of cheap prices. When it comes to funding, it is difficult to change it. PVC releases organic gas, and the package is in this environment, which will gradually discolor the material and corrode the metal. The air permeability and moisture permeability of the film is higher than that of the plastic/plastic composite film (see the following table). The poor performance of "defense" is obviously unfavorable to the storage and transportation protection of military electronic equipment. Since the film is inexpensive, the resulting loss is not compensated.

Foreign countries pay more attention to the research and measurement of protective properties of packaging materials. Such as France, for military products and precision instrument packaging film strictly detect and control the harmful components, including halogen content and sulfur content of less than 50ppm, chloride and fluoride are also a certain degree of control, otherwise it is strictly prohibited. In comparison with China, there are differences, and the materials used for military packaging are generally not measured for harmful elements, let alone strictly controlled.

(to be continued)