Selection of Dry Box for Humidity-sensitive Devices Complying with J-STD-033 Standard

1, the dry box application and improper selection problems.
Moist gas will enter the inside of the IC device through the bonding surface of the encapsulating material and components, causing oxidation and corrosion short circuit of the internal circuit, and the high temperature during the group welding process will cause the humid gas entering the IC to expand due to heat to generate pressure and make the plastic from Internal separation (delamination) on the chip or lead frame, wire bond damage, chip damage, internal cracks and cracks that extend to the surface of the component, and even bulging and bursting of the component, also known as “popcorn”, will result in The assembly was repaired or even scrapped. What's more important is that those invisible and potential defects will dissolve into the product and cause problems in the reliability of the product. Instead of IC electronic components, there are also wet hazards.
The harm of moisture to electronic components has become a very serious matter. With the increase in the use of moisture-sensitive components, such as thin fine-pitch components and ball grid arrays, the more serious the problem is, the quality control of electronic companies. Presented serious challenges.
To this end, IPC and JEDEC have jointly researched and developed IPC-M-109, Standards and Guidelines for Moisture Sensitivity Components, and moisture protection and dehumidification for electronic products. Proposed and set standards, and become the standard that the global electronics industry follows.
IPC/JEDEC in IPC-M-109 J-STD-033 Moisture/Reflow Sensitivity SMD Handling, Packing, Shipping, and Use Standards for ICs that have been exposed to moist air In the RH10% drying oven, to restore IC life. Therefore, various electronic companies are planning to purchase normal-temperature automatic drying ovens (also called drying cabinets, electronic drying ovens, etc.) that can control the humidity inside the cabinet to be below RH10%. Therefore, on the issue of the selection of this kind of product, we put the desktop.
Since this normal temperature auto-drying box is an emerging product, the average user does not understand its situation, and is easily exposed to the appearance of the product, such as the price and the appearance, or it is easily induced by the salesman. Therefore, it is often difficult to select the type accurately. In fact, many users in various parts of the country feel that the product is not satisfactory after purchase, and they are concentrated in the following aspects:
1, long dehumidification time. From RH70-80% of indoor humidity will be faster than RH10% to 8-12 hours or more, slow 3-5 days, or even 10 days and a half months, and some will not come under the humidity.
2. When RH10% is reached, once the door is opened and removed and the indoor high-humidity air enters the box, the drying box cannot start dehumidification immediately.
Instead, dehumidification begins after a “pre-run” that is not dehumidified for more than about 2 hours, and then enters a “pre-run” stage where it is not dehumidified after a period of time. This is repeated, and the dehumidification can be reduced again after prolonged dehumidification. To RH10%. This is extremely inconvenient for users. With impatience, some users only adjust the rhythm of production to adapt to the rhythm of the drying oven, or only use the unused ones as a storage type. For users who want to use the oven as a tool, they will not be able to purchase it.
3, product life and reliability issues. Some products are only used for a short period of several months. After two or three years of continuous use, they are gradually dehumidified and not dehumidified.
While some products have been used for more than 10 years, they are still working properly without failure.
4, anti-static problem. Some products do not have antistatic measures, causing the IC to be damaged by static electricity.
According to the reasons for the above problems, it is necessary to analyze the structure of the products such as the normal temperature automatic drying oven to find out where the problems are, and provide scientific decision-making basis for product selection of users.

2, the structure and type of normal temperature automatic drying box
At present, it can be referred to as the electronic drying cabinet, electronic drying box, etc., the name "automatic drying oven at room temperature," the dehumidification principle of the cooling type and the physical decomposition of moisture removal of two major categories. Among them, the refrigerated drying box uses a semiconductor cooling sheet to eliminate condensation after condensation of moisture in the air. Domestic products include Huitong, which is produced in Zhuhai, and Hushi, which is produced in Chongqing. Since the refrigerated drying cabinet cannot reduce the humidity below RH10% regulated by the IPC/JEDEC J-STD-033 standard, it is not an example discussed in this article.
The moisture physical decomposition type drying oven was first found in Cartman (Chengdu) Electronics Co., Ltd. in China. Cartman also obtained Chinese patent authorization. A few years later Zhuhai's "Blessings" and Taiwanese "collectors" began to follow suit. In the past three to four years, some manufacturers have followed suit. With the implementation of the IPC/JEDEC J-STD-033 standard, the normal temperature automatic drying oven has been used in the electronics industry in recent years and is gradually expanding.
Water Physical Decomposition Exhaust Drying Chamber The normal temperature automatic drying oven is an electromechanical integrated product. According to the power source generated by its mechanical action, it is divided into two categories: memory alloy drive and micro motor drive. The purpose of its power is to drive the opening and closing of the dehumidifying moisture removal door of the drying box so as to achieve the purpose of discharging moisture inside the box to the outside of the box. The key to the long-term reliable opening and closing function of the tidal outlet door is the most important key factor concerning the life and reliability of the tumbler product and the safety of the stored article.
The so-called memory alloy, is to add some nickel-titanium alloy components in the metal material, and then drawing spiral made into a spring. The memory alloy spring is placed in an aluminum tube with a heating device, and then combined with a reset tension spring and a pull rod to form a continuous motion mechanism. The heater is energized and heated, so that the memory alloy spring is shortened by heat, and gradually generates a pulling force, which lasts from several minutes to ten minutes. Pull the Dehumidifier's tidal outlet door to the left and right. After tens of minutes of discharge, the heater is de-energized and cooled. The memory alloy spring cools and cools and is restored by the return spring. The dehumidifier drain door is closed, and the dehumidifier dries the air inside the box. Repeatedly back and forth to achieve the purpose of dehumidification.
Although memory alloy materials have been available for a period of one to twenty years, their research and understanding are still far from sufficient. Although it is known that the temperature change can cause the metal crystal phase to produce a memory effect during the mutual transformation of martensite and austenite, the mechanism of its principle is still not clear, and many links cannot be repeated with scientific methods. Sexual reproduction, there are still many unsolved secrets. Therefore, the memory alloy material is still only at the preliminary application stage, and all countries in the world have not yet had national or international standards concerning memory alloys.
With the current state of the art, there are many problems with memory alloy materials. The main reason is that its characteristics are greatly affected by time and environmental factors. Unexplained reasons often result in the loss of memory, that is, inability to move. As a power source driving the dehumidifier's tidal outlet door, reliability is not as high. The most prone to failure is that after a period of use, the desiccant dehumidifier tidal outlet door may suddenly not open, causing the moisture-proof case to be dehumidified. Or the stroke is not half-opened and half-closed, so that the air inside and outside the box can communicate with each other, causing the humidity inside the box to rise. In particular, on products with high frequency of door-to-door access, the memory alloy springs frequently shorten the elongation and greatly accelerate the fatigue aging process. This problem cannot be overcome at present. This is also the root cause of the short lifespan and low reliability of some products. There is also a problem with the memory alloy-driven products in that the temperature of the memory alloy spring caused by the stroke is slowly shortened or elongated. In winter, the door is slow to open, the summer is closed slowly, and the time for the action journey is completed, which ranges from several minutes to more than ten minutes depending on the ambient temperature. That is, the opening and closing motion of the tidal outlet door takes a time of several minutes to ten minutes. In such a long half-closed state, the high-humidity air outside the box will intrude into the box to humidify the inside of the box. Therefore, the dehumidification workload and the memory alloy spring are burdened, and the dehumidification speed is also reduced.
Micro-motor-driven products are designed to solve the shortcomings of the memory alloy springs in terms of life and reliability. According to the limit workload of the dehumidifier that never stops, the tidal outlet door is opened and closed 12 times per day. The rotation of each stroke motor is about 5 seconds, the rotation time is one minute a day, and the total one year rotation is one hour. 10 10 hours a year. On the other hand, the motor has a low life of thousands of hours and a high one of ten thousand hours. Therefore, it is normal to use a dry box driven by a micro-motor for more than ten years without failure. This results in long life and high reliability. Since the operation of the opening and closing door is completed in a few seconds, there is no problem that the high-humidity air outside the box invades the inside of the box, and the dehumidification speed is faster than that of the memory alloy.
Carter’s early products used a memory alloy as a power source, and later found that the problem of the memory alloy was changed to a micro-motor as a power source. However, in the last year, the need for low-price competition in the market, Cartman has relied on certain products. The use of complex memory alloys as a power source began. All other manufacturers' products have been using memory alloy as a power source. Therefore, at present, a commercially available normal-temperature automatic drying box is a product using a memory alloy and a product driven by a micromotor.
The process of dehumidification of the moisture physical depletion drying box is when the humidity sensor detects that the humidity in the box is higher than the user's control setting.
By controlling the actuator to start the dehumidification work, first, the heating element in the drying box in the dehumidifier is heated and the open damper door is driven at the same time, so that the existing moisture of the drying box is evaporated to a gaseous state and escapes through the outlet of the moisture discharging door. Outside the box. After tens of minutes of tidal discharge, the counting is completed, the power supply is stopped, and the temperature is lowered. Cooling time dehumidifier size, different models of each plant and different temperatures in winter and summer and there are differences. About dozens of minutes to an hour or so. The dehumidifier is not dehumidified during the heating and cooling periods. The merger of these two phases is also referred to as the "pre-operational" phase, which takes about one and a half to two hours. When the cooling is completed, the tidal outlet door is automatically closed to make the drying box open to the inside of the box, ie, the drying time is short. As the drying time progresses, the air in the box is continuously transferred to the drying box, and the humidity in the box is continuously reduced. When the drying process is carried out for a certain period of time, the dehumidifier tidal outlet door is automatically closed again and opened to the outside. The heater heats up and the water is discharged. . . . . . In this way, until the humidity in the box reaches the value set by the user control, the drying box enters an off-hold state. If the humidity in the tank rises beyond the user control setting value due to factors such as door opening or natural penetration, the cycle starts again from the beginning. Drying time process, according to the different models of each plant, the size of the dehumidifier is different, the humidity requirements are different and there are differences, roughly in about 1-3 hours. Comparison of the “pre-run” time with the dehumidification time can not dehumidify the products for about 1/3 to 1/2 of the time. Therefore, this type of drying method is a gap type dehumidifier type. According to the products of different manufacturers, empty-box testing, from RH70% of the indoor humidity to RH10% or less, fast to 6-12 hours, slow 3-5 days, even up to 10 days and a half months. All in all, such products dehumidify slowly.
In addition, Carterman has recently put into production a continuous dehumidifier model. This type of work does not have a "pre-run" process that does not require dehumidification and is always in a dehumidifying state. Dehumidification is fast, is Cartman's exclusive production of patented products.
Commercially-available drying boxes conforming to the IPC/JEDEC J-STD-033 standard belong to gap-dehumidification type models. There are currently a number of Cartman's "Carteman SSD Series" products; Han Tang's "Dr.Storage SDX, XDE and Meiyang HDE Series" products, "Dean Ocean CMT L (A) Series" products of Jiangsu Kunshan Dry Dr. It was also known that the “Dr. Door” brand of the same type was produced at the same address and the same factory of the “Dr. Doctor” in Kunshan, Jiangsu Province, but the legal person qualification of the company has disappeared.
The continuous dehumidification type is Cartman's "CARTEMAN ULD series" product.

3, the main points of the normal temperature automatic drying oven selection according to the IPC/JEDEC J-STD-033 standard
(1) Selection according to application requirements Since the rate of dehumidification of the gap-dehumidifying product is slow, it can reach RH10% or less and meets the requirements of the IPC/JEDEC J-STD-033 standard. However, this product is actually more suitable for storage users who do not open the door frequently. For example, the research laboratory department is not a user who has to open the door to pick and place items every day.
For users who use the drying oven as a tool type in a workshop, etc., users who open the door several times a day have problems using the gap dehumidification product: even if a product that can lower the humidity during 6 hours is used, it is not because the user is using the empty container but it is used instead. With items such as ICs, the moisture absorbed in these items is continuously extracted, which is equivalent to constantly humidifying the inside of the box, so the down time will be longer, it may be 8 hours, or 10 hours, depending on the type and quantity of items. Wait. Therefore, the eight-hour work schedule passed one day and it was impossible to open the door to pick up and release the items at all. It was finally easy to just drop down, open the door to pick and place items, and immediately enter the “pre-run” state without dehumidification, and then wait another eight hours before Down. The problem is that according to IPC/JEDEC standard J-STD-033, for moisture-sensitive SMD devices with a level of 5-5a, the moisture-proof packaging should be exposed to less than or equal to 30°C/60% RH after being unpacked. For example, for 20 minutes, it will be put in a normal-temperature drying oven with a humidity of 10% RH and dried for 200 minutes, that is, a dehumidifying storage time of about 3 and a half hours before the original life can be restored. If the moisture-proof packaging is exposed and the exposed air environment humidity is higher than RH60%, for example, RH70-80% environment, the time to put in the drying oven to restore the life will be greatly extended. Otherwise, the product quality cannot be guaranteed. Therefore, the time to recover IC life is from 10% to 20hrs after the “pre-run” of the drying oven is reached until it reaches RH10% and the length of the dry storage time that satisfies IC life recovery is completed. the above. Obviously, this can not meet the needs of workshop production. As for the dehumidification time of up to three or five days, or even ten and a half months, it is even more unusable. Therefore, as a workshop tool type, gap dehumidification products are not a good choice.
(2) According to the reliability requirements, the type of dry box used for long-term storage is selected. Since the number of times the door is opened and removed is small, once the humidity in the box drops to the user-defined control value, it will not start for a long time. The durability of power sources driven by tidal gates is correspondingly lower. As for the users of the tool type, due to repeated frequent opening and closing of the tide gate, the durability requirements for the power source are high. If a memory alloy-driven drying oven is selected, it will cause the memory alloy springs to “over-fatigue” and the lifespan will be greatly shortened, and the drying oven will be prematurely failed. For example, a certain vacuum device unit in Anhui Province bought several “Dr. Door” drying ovens driven by large memory alloys. They frequently opened doors to pick and place articles in use. In two years or so, there have been memory alloy spring failures and drying ovens. Can not dehumidify the situation. What's worse, the memory alloy spring is a factory-made part rather than a universal part. It can't be bought outside, and the "Dr. Door" is closed again. The unit has no doors for repairs, investment has gone awry, and it has also affected work. This situation also appeared in Shanghai, Guangdong and Xiamen. With the extension of the use of time, these conditions will also appear in various places in succession. Therefore, for the use of tools, and storage of important items, users with high reliability requirements should not choose memory alloy driven products.
(3) Selection according to the requirements of anti-static electricity The hazards of static electricity to electronic devices are well known. The lower the ambient humidity, the greater the electrostatic hazard. Therefore, when picking and placing ICs in an ultra-low humidity and dry environment below RH10%, it is necessary to purchase stainless steel box products or to purchase products with anti-static coating sprayed on the box partitions. In addition, the box should also have static discharge grounding piles. Anti-static coating has anti-static paint and anti-static resin two kinds, baking paint color changes, and can be used to scrape the paste to cover the box welding traces, the appearance is more beautiful, but the wear resistance is poor, you can use nails to mark, The use of this environment in the workshop may become a “cloth” after a few years. The color of the resin is simple, and the effect of masking the welding marks is not as good as baking paint, and the appearance is slightly inferior to the baking paint, but the abrasion resistance is good. Considering this environment and long-term use in the workshop, it is advisable to choose a product that sprays antistatic resin.
(4) Selection according to the requirements of control accuracy
A. All-digital circuit products controlled by a calculator, electronic humidity sensor and digital humidity meter, CPU, memory, etc. The feature is that the user sets the humidity in the box to use the "+" "-" key or "up" and "down" keys. Without a click, the set value increases or decreases by 1%. Press and hold the setting value will continue Rise or fall. This product has high control reliability and accuracy.
B, mainly analog circuits, some digital circuit hybrid products. Electronic humidity sensor and digital hygrometer, but no
CPU, memory, etc. The feature is that the user sets the humidity inside the box to use multiple light emitting diodes to display segments, and then click one set button to jump one light emitting diode to light up, indicating that the humidity setting in the box is increased or decreased by 10%. Continuous setting cannot be performed in units of 1% humidity. . This product can not be set accurately, and control reliability and accuracy are not as good as the products controlled by the calculator.

4 Conclusion
(1) The use of a storage type or infrequently used to open, pick, and place articles can be used to select gap-dehumidifying models;
(2) The continuous dehumidification type should be selected for the tool type use;
(3) When the work is completed, the short-term users such as the dismantled project team can use the optional memory alloy drive model;
(4) For the use of tools and storage of important items, users who require high reliability for long-term use should select models driven by micro-motors;
(5) The box must be coated with anti-static paint and have static discharge piled on ground or stainless steel box, but the price is high.
(6) The former is selected between a fully digital circuit product controlled by a calculator and a hybrid circuit product mainly composed of an analog circuit and some digital circuits.
(7) Some other functions such as temperature display are fancy functions.
(8) The horizontal price comparison of different manufacturers' products must be compared between products of the same structure, but not between products of different structures. It is also not advisable to regard price as the main orientation. The fundamental purpose of buying a product is to satisfy the purpose of use, not purely for "cheap". Satisfy the use requirements, can be used reliably for a long period of time, and may be in the best interest of the user.

5, part of the normal temperature automatic drying oven technical status list (according to the manufacturers of product data)
Carter ULD series Cartman SSD series High-strength SDX series High-strength XDE series Mayo HDE series Deyang CMTL(A) series Humidity 1-5% 5-10% 5-15% 1-10% 1-50% 1- 40%
Tidal Gate Drive Micromotor Drive Micromotor Drive Memory Alloy Drive Memory Alloy Drive Memory Alloy Drive Memory Alloy Drive Control Circuit Calculator Control All Digital Circuit Calculator Control All Digital Circuit Calculator Control All Digital Circuit Calculator Control All Digital Circuit Calculation The device controls the humidity setting mode of “+” and “-” in the analog and digital mixed circuit of the all-digital circuit. The change value is 1% “Up” and “Down”, and the change value is 1%. The “Up” and “Down” keys change value. 1% “Up” and “Down” keys, change value 1% “Up” and “Down” keys, change value by 1% Segment setting change value by 10%
Dehumidification method Continuous dehumidification clearance Dehumidification clearance Dehumidification clearance Dehumidification clearance Dehumidification clearance Dehumidification Antistatic coating Standard box body spray Antistatic resin Standard box body Spray antistatic resin Standard box Common paint, optional spray antistatic paint Standard box Common paint, Available Select spray antistatic paint ordinary paint. The data is not clear whether it is optional spray antistatic paint antistatic paint

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Dehumidifier,Others Dryer,Plastic Machine

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