Testing Questions

 Q: Why there is no difference of the test result between ordinary silicone grease and epoxy resin, even worse?

A:    Generally there are two causes of the problem:

       1). Our product doesn’t been operated in accordance with the standard operating mode. The conductive adhesive is unable to achieve

       the best thermal conductivity performance without curing condition.

       2). The method of measurement and evaluation is not accurate.

       So far the most common method of measuring temperature is by testing temperature point or pin TJ to estimate the actual work.

       It’s not suitable for the testing of whole lamp. 

       LM-85 of United States indicate that judge the junction temperature of the whole lamp by measuring temperature of the PIN

       on substrate is wrong. 

The original quote: 

       lighting product manufacturers often need to know the performance of LEDs operating in full rated DC current at a thermal equilibrium

       at much higher temperatures than 25.  

       To set or measure the thermal conditions of the LED,"case temperature","pin temperature","board temperature","solder-point temperature"

       or "heat sink temperature" are commonly used depending on the type of LED. While these methods are useful  to reproduce the same

       condition for the particular LED.  

       The results using these different methods cannot be compared with each other and cannot be reconciled into a universal standard method.   

 

       The only method recognized by the internet is JESD51 series by the organization of JESD51, that is to test the actual TJ through the forward

       voltage method. On Dec. 5, 2014, the first CALT 001-2014 standard release by the National Institute of Lighting quality inspection technology

       Alliance. The standard is able to helps customers to control the actual working TJ of the whole-lamp. Silanex laboratory is also in accordance

       with the national standard for testing. If you do not have the condition, offer us the sample light and let us to do the comparison test and

       analysis for you and provide the test report.( click here to download) 

 

      If heat dissipation design is not reasonable, the difference of our thermal conductive adhesive is not very distance from silicone grease.

      Because the test of thermal resistance depends on temperature differences and temperature differences are relative to radiators power,

      thickness of interface materials and contact area, etc. (such as due to the inefficient of radiator power, the system heat would become

      balance soon with smaller and smaller temperature difference.) In addition, our product has stable performance except high thermal

      conductivity power. It won’t appear decline of thermal capacity cause of thermal cycle or vibrations. 

 

Q:What’s the true meaning of test junction temperature? 

A:   1. Directly measure the junction temperature of LED chip. Thermocouple or infrared thermal imagers cannot get accurate

      LED junction temperature. So it’s impossible to accurately assess the product life and reliability through these two kinds methods.

      2. Measuring the LED junction temperature by using its own driving power under actual working conditions.

      In order to restore the real thermal environment and avoided the error of testing by using the other driving power.

  

Q: If you choose high thermal conductivity radiator to solve the thermal problem, does it means we don’t need

    thermal conductive adhesive any longer?

A:  No. LED lighting thermal conductivity is system engineering, any link cannot be ignored. The thermal resistance is consisted of thermal

     resistance from heat source to radiator + thermal resistance of radiator itself. It won’t reduce whole-lamp heat resistance only by lowering

     the heat resistance of the radiator itself. Thermal conductive adhesive is the main bollteneck of whole-lamp radiating. It only raises very

     little cost of whole-lamp. If you choose better radiator, the cost would increase by more than 5%. Part of domestic light plant also will

     rely on us technology to make up for the LED insufficient conductive power due to their immature LED packaging technology. 

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