【Exchange of experts in 2009 and examination of the use of pressure-sensitive mine chips
Column:Company News Time:2019-12-04 Browsing volume: 499
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 Flyboat To help customers better understand and use the pressure-sensitive mine chips, special preparation of this guidance note.

1. Pressure-sensitive chip in mine production and use of common problems and their performance:


 Question Type

 Manifestations

 Identification of

 Notes

 Slightly damp

Leakage current I L increases or climbing, action, voltage drop U 1mA

 After drying I L, U 1mA back to normal;

 As soon as the use of drying

Epoxy resin casting process performance degradation caused by improper

 Encapsulated module leakage current I L increases or climbing, action, voltage drop U 1mA.  Access grid quickly heating failure, if the heat from the body can cause bad fire.

 Potting before I L, U 1mA normal, encapsulated the leakage current I L increases or climbing, action, voltage drop U 1mA; Fei Ge casting process in accordance with potting I L, U 1mA to normal.

 Fei Ge casting process in accordance with potting.

Of inferior quality, contaminated, non-reversible damp

 1. Leakage current climbing; 2. Pass flow is poor; for example, 34S single-chip Imax ≤ 40kA.

 1. Drying leakage after the climb of no improvement; 2. 34S single-chip 40kA shock U 1mA exceeded the rate of change.

 Damp potting or minor leakage caused by climbing is not included.


flyboat MOV typical epoxy resin casting process

Special Note: In order to prevent the potting material losses caused by fluctuations in batches, each batch be sure to go through a small amount of test verification, practical and then put into large quantities so as to avoid big loss.

According to a large number of experimental research, our company summed up as follows for lightning protection chip varistor (MOV) typical of epoxy resin encapsulation process for you the user information.

a) to determine the appropriate ratio of curing agent: Due to MOV easily and curing agent matrix chemical reaction leading to insulation resistance is lowered, causing serious consequences, it is not a simple epoxy resin manufacturing plant in accordance with the recommended ratio (ratio of curing agent is often too high) for the production , but should just make the curing epoxy resin curing agent ratio of the best (curing agent resin component has been completely absorbed); is usually available from the epoxy resin production plant around half of the recommended ratio of attempts to arrive at the optimum ratio ;

b) encapsulation before the first chips dried at 100 ℃ under 30 minutes, placed in the module box;

 c) a single-component resin is heated to about 40 ~ 50 ℃ in order to make it flow well; curing agent in accordance with the best ratio of good to join the full mix thoroughly, and mix thoroughly how to adjust the amount of time under the gum, but it should ensure the full and mix thoroughly in order to cure agent has been completely absorbed resin, to avoid the existence of free states of the curing agent reacts with the silicon, resulting in chip deterioration; and mix thoroughly after filling glue;

Heating curing benefits are: high temperature plastic flow of excellent short period of time, which will help free state curing agent dispersion and absorption are plastic to prevent chemical reaction with the chip; the lack of conditions for curing at room temperature users can, as long as the full mix well There is no any problem.

e) units and collaboration with our company in accordance with this process is casting a 200 MOV chips, including the initial 25-chip leakage current I L = 10 ~ 25μA, encapsulated 100 using heat-curing, curing at room temperature using 100 All product leakage current I L <10μA; pass rate of 100%.

f) Recommended Shanghai continents Electronic Materials produced by the following two types of potting epoxy resin: DC-5480BK/DH-5480H and DC-505WH-1-P/DH-505YLX-1, according to 100:12 wt ratio of curing agent with glue, you can add 10% SAF-S680A to prevent the glue along the copper wire climb. 華東聯係電話為:021-64588585、華南聯係電話為0769-82775941。 East China Contact Tel :021-64588585, southern contact telephones 0769-82775941.

2. Varistor lightning-chip key performance indicators for testing elements and methods:

Special Note: Due to the domestic Gejia test equipment varies greatly, comparative test should be that products on the same piece of equipment subject to the test data, rather than simply copying the data provided by Gejia self-comparison.

 Mine the pressure-sensitive chip is divided into key performance indicators for testing compliance inspection and testing two types of competition, if the user just requested products meet national standards, the use of compliance testing before; if users want to choose the best products, you should test the use of race . In addition, some indicators of compliance can be, demanding no good; some, you should choose the best. With 34S-type side pieces, for example, the specific test methods recommended by the following table:



Performance

 Standards

 Compliance testing

 Competition test

 Description

flyboat product level

 U 1mA Voltage

 Nominal value of ± 10%

 


Usually the two sides agreed upon by -5% ~ +10%

 To meet customer agreement.

Leakage current I L

 ≤ 20μA; the impact of post-increment ≤ 200%


 Is not as small as possible, the stability of the most important, namely, the rate of change after the impact of the small.  Foreign products are often 10 ~ 30μA.

 ≤ 10μA or by agreement; where I L ≥ 5μA products in In20 Ci + Imax1 second post-increment ≤ 100%, ranking the industry’s highest level of stability.

 8/20μS Flow

 GB: In ≥ 20kA, Imax ≥ 40kA; learn the highest level of standards: In ≥ 25kA, Imax ≥ 60kA.


 Simplify: 20kA20 times +40 kA2 times U 1mA after the change rate of ≤ -10%, I L ≤ 20μA for compliance; the industry’s highest level: 25 kA15 times +60 kA2 times U 1mA after the change rate of ≤ -10%, I L ≤ 20μA; have Conditions can also be carried out 100 times, 1000 times, 10,000 times the largest-pass flow test, the same current, the number of the better tolerated.

 25 kA15 times +50 kA2 times U 1mA after the change rate of ≤ -10%, I L ≤ 20μA, ranking highest in the industry standard.  Flyboat 32D wafer that is to reach the majority of domestic counterparts 34S square piece Flow capacity, alternatives to the use to reduce costs.

 In the next residual voltage Ur

 SPD level of protection at different levels U P requirements.


 Ur, if low enough can be improved to enhance the U 1mA level over-voltage tolerance, while the U P is still compliance, and can greatly enhance the SPD security.

 34S681 chip 20 kA residual pressure ≈ 1.5kV, produced SPD after the U P ≤ 1.75kV.  Can replace 34S621 to improve the security of SPD.

 10/350μS

 Flow

 Society criteria for tolerance of a wide wave energy requirements.


 Bigger the better, the domestic general chips ~ 4kA; the industry’s highest level of ≥ 5 ~ 6kA.

≥5kA

2mS方波通流 2mS square-wave-pass flow


 Bigger the better, the domestic general chips ≤ 250A; the industry’s highest level of ≥ 300A.

≥300A

 Limit power frequency overvoltage tolerance

 Institute of Standards demands.


 ≥ 1.5Uc imposed by the power frequency overvoltage in order to chip center of the surface temperature ≥ 150 ℃ when the breakdown does not appear qualified criterion. The industry’s highest level of ≥ 1.8Uc.

~ 1.7Uc; static testing industry, second; 50kA test the impact of a second after the industry first.

Maximum thermal equilibrium voltage

Flyboat proposed


 Does not appear to impose the maximum thermal collapse of the AC voltage RMS.

≥0.8U 1mA


3. Guizhou Fei Ge Electronics Co., Ltd. MOV Features Introduction:

 3.1. Raw material purification establishment of the center will handle all the necessary purification of raw materials in full accordance with the standard process purification treatment, batches of products completely solve the stability problems;

 3.2. Fei Ge MOV product residual down, pass flow better: 34S Thick largest chip flow passage ≥ 60kA; 20kA under 34S621 residual pressure ≈ 1350V, 34S681 residual pressure ≈ 1500V, thin chip residual pressure lower; Flow capacity far superior products such as foreign-funded enterprises in APEX.  32D series of products can be achieved In = 20kA, Imax = 40kA demand, and considerable foreign 34S product, which can effectively reduce costs to consumers.  General single-pass flow pulse maximum size and constant-current pulse withstand several times the number of positive correlation between the.

 3.3. Fei Ge product limit power frequency overvoltage tolerance, although not the industry first, but it is the only way to achieve the Ministry of Information Industry of basic practical requirements of the manufacturers: About 1A-frequency current, non-fire tripping.

 3.4. Fei Ge MOV depressed due to residual can be used to improve varistor voltage U 1mA (to replace the 621 with the 681 chip) approach to improve the over-voltage tolerance levels, while SPD level of protection U P will not be exceeded.  Using this program can significantly improve the SPD at the power frequency over voltage safety performance.

 4. For YD/T1235.1 standard SPD thermal stability test provides an analysis of understanding:

 4.1. YD/T1235.1 heat stability test is an extreme case the provisions of the assessment: To Uc = 385V the 20kA rating SPD (using pressure-sensitive mine 34S621 chips) generated around 1A-frequency currents, must be present and effective value ≥ 600V AC voltage; low-voltage distribution system between the L-N in such a high over-voltage despite the analysis of reports, but at least it is extremely rare.  Such cases can not be sure that thermal breakdown of thermal stability, thermal stability test is not appropriate to call it.

4.2. SPD majority of the fire was due to the improper selection of materials or devices to create a low level (for example, body heat from the failure) or N-PE between the frequency of high amplitude caused by over-voltage breakdown, rather than in L-N between the frequency of more than 600V over-voltage breakdown caused by MOV.

 4.3. Domestic mine sector has provided considerable controversy, such as Beijing Mine Center, Shanghai Mine Center, Shanghai Electric Division and other departments have basically held a negative view; the international community has also seen a lot of stress or demands.

 4.4. There is some power in the only over-voltage amplitude, resulting in the size of the current depends on the impedance characteristics of the device; that is the same over-voltage at different currents generated by SPD in different sizes; it is used to assess voltage rather than current SPD The power frequency overvoltage withstand characteristics are more reasonable.

4 4.5. Really prone to failure because the SPD in the L-N between the rms-frequency over-voltage ≤ 500V (single-phase zero or ride to +30% power fluctuations) and the high frequency of the combined effects of lightning surges.  In this harsh conditions, the maximum heat balance SPD voltage and 8 / 20 μ S Flow capacity will play a decisive role; maximum heat balance voltage to more effectively measure the SPD at the power frequency over voltage safety performance.  Obviously as long as the residual voltage U P level of protection to meet the requirements of the MOV on the same gradient, a high-U 1mA value of a clear asset.


 (34S single-chip In = 25kA, Imax = 50kA)

 (32D single-chip In = 20kA, Imax = 40kA)

 (25D single-chip In = 10kA, Imax = 20kA)

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