CN102183546B - Detection device and method for package interface of light emitting diode - Google Patents
Detection device and method for package interface of light emitting diode Download PDFInfo
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- CN102183546B CN102183546B CN201110007730.0A CN201110007730A CN102183546B CN 102183546 B CN102183546 B CN 102183546B CN 201110007730 A CN201110007730 A CN 201110007730A CN 102183546 B CN102183546 B CN 102183546B
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Abstract
The invention relates to a detection device and a method for the package interface of a light emitting diode. The detection device for the package interface of the light emitting diode (LED) used for the detection of LEDs comprises a current source, a voltage detection device and a test control unit. The current source is commanded to output at least one current to the LED element by at least one control signal provided by the test control unit. At least two signals are provided so as to respectively command the voltage detection device to measure the first forward voltage of the LED element at a first time and the second forward voltage thereof at a second time. The voltage difference valve between the first forward voltage and the second forward voltage is calculated by the test control unit. When the voltage difference valve is greater than a preset failure judgment value, the LED element is determined to be invalid.
Description
Technical field
The present invention relates to pick-up unit and the method for a kind of light emitting diode (LED) package interface.
Background technology
LED processing procedure comprises die bond, routing, sealing and detection, and wherein die bond processing procedure uses die bond material (as elargol, eutectic alloy or heat-conducting glue etc.) to be pasted and fixed on package carrier or substrate by LED chip.If the phenomenons such as in uneven thickness, hole, deterioration in characteristics occur die bond material in die bond process, die bond interface quality will be caused to have fine or not uneven problem.Encapsulate on the Quick photoelectric Characteristics Detection machine before dispatching from the factory in LED element at present and there is no the detecting step carrying out the screening of die bond quality.The bad meeting of die bond quality makes LED element thermal resistance value higher, and heat conduction is bad, when subsequent clients is applied, LED will be caused overheated, ahead of time the problem such as light decay or damage.
The method of current assessment LED element thermal conduction characteristic such as adopts thermal resistance measurement board to carry out thermal resistance measurement according to standard JEDEC-51, MIL-STD-883, CNS15248, but because thermal resistance measurement step complexity is consuming time again, the instant QC test item before cannot dispatching from the factory as LED element.
Summary of the invention
The present invention proposes one LED interface detection method and device fast, time-consumingly need not measure the thermal resistance value of LED element, each LED element only need can tell the difference of package interface (such as die bond) quality between each LED element less than the time of several seconds.This detection method and device are combined with general LED Quick photoelectric Characteristics Detection machine, before LED element is dispatched from the factory, the screening of die bond defective products can be carried out fast.
The pick-up unit of light emitting diode (LED) package interface of one embodiment of the invention, detects for a LED element with a package interface.The pick-up unit of LED interface comprises current source, voltage check device and unit of testing and controlling.Unit of testing and controlling provides at least one this current source of control signal order to export at least one electric current to this LED element, and at least binary signal is provided, this voltage check device is ordered to measure one first forward voltage (forward voltage) of LED element in a very first time respectively, and in one second forward voltage of one second time measurement LED element.Wherein this unit of testing and controlling calculate this first and the voltage difference of this second forward voltage, and judge when this voltage difference be greater than one preset fail-ure criterion value time, then this LED element is judged to be inefficacy.
The detection method of the LED interface of one embodiment of the invention, detect for a LED element with a package interface, it comprises following steps: provide at least one electric current to this LED element; This at least one electric current is utilized to measure one first forward voltage of this LED element in a very first time, and in one second forward voltage of one second this LED element of time measurement; Calculate this first and a voltage difference of this second forward voltage; And judge that when this voltage difference is greater than a default fail-ure criterion value, then this LED element is judged to lose efficacy.
The detection method of the LED interface of another embodiment of the present invention, detect for multiple LED element with package interface, it comprises following steps: provide at least one electric current; This at least one electric current is utilized to measure one first forward voltage of each LED element in a very first time, and in one second forward voltage of one second each LED element of time measurement; Calculate each LED element this first and a voltage difference of this second forward voltage; And to classify the plurality of LED element according to this voltage difference of each LED element.The very first time of wherein measuring each LED element is all identical, and second time of measuring each LED element is all identical.Adopt same detection condition by this, to carry out the classification of multiple LED element.
Another embodiment of the present invention comprises a kind of computer program of the package interface for detecting a LED element, it comprises the computer read/write memory medium that contains a computer-readable medium instruction, and this computer-readable medium instruction comprises to give an order: one first instruction provides at least one electric current to this LED element; One second instruction utilize this at least one electric current in a very first time measure this LED element one first forward voltage and in one second forward voltage of one second this LED element of time measurement; One the 3rd command calculations this first and a voltage difference of this second forward voltage; And one the 4th instruction judge when this voltage difference be greater than one preset fail-ure criterion value time, then this LED element be judged to be inefficacy.
Accompanying drawing explanation
Fig. 1 display is assembled in the package interface schematic diagram of the LED element of circuit board.
Fig. 2 shows two forward voltage differences of LED element with the graph of a relation passing into current time increase.
Fig. 3 shows the block schematic diagram of the LED interface detection apparatus of one embodiment of the invention.
Fig. 4 is the flow chart of steps of the detection method of LED interface of the present invention.
Fig. 5 is the test electric current of first embodiment of the invention and the corresponding relation figure of forward voltage and time.
Fig. 6 is the test electric current of second embodiment of the invention and the corresponding relation figure of forward voltage and time.
The forward voltage difference that Fig. 7 shows LED element increases and the experiment measuring figure of increase with passing into current time.
Fig. 8 is the test electric current of third embodiment of the invention and the corresponding relation figure of heating electric stream and forward voltage and time.
Fig. 9 is the test electric current of fourth embodiment of the invention and the corresponding relation figure of heating electric stream and forward voltage and time.
Figure 10 is the test electric current of fifth embodiment of the invention and the corresponding relation figure of forward voltage and time.
Figure 11 is the test electric current of sixth embodiment of the invention and the corresponding relation figure of forward voltage and time.
Figure 12 is the test electric current of seventh embodiment of the invention and the corresponding relation figure of heating electric stream and forward voltage and time.
Figure 13 is the test electric current of eighth embodiment of the invention and the corresponding relation figure of heating electric stream and forward voltage and time.
Figure 14 is the test electric current of ninth embodiment of the invention and the corresponding relation figure of heating electric stream and forward voltage and time.
Figure 15 is the test electric current of tenth embodiment of the invention and the corresponding relation figure of heating electric stream and forward voltage and time.
Figure 16 is the flow chart of steps of the detection method of another embodiment of the present invention LED interface.
[main element symbol description]
10 LED element 11 chips
12 package carrier 13 die bond interfaces
14 assembling interface 15 circuit boards
16 package interfaces
The pick-up unit of 20 LED interfaces
22 current source 23 voltage check devices
24 unit of testing and controlling 25 LED element
T1 very first time t2 second time
Th heat-up periods time td interval time
V1 first forward voltage V2 second forward voltage
S1, S1 ', S1 ", S1 " ' control signal S2, S3 signal
Embodiment
For fully understanding feature of the present invention and effect, hereby by following enforcement example specifically, and graphic appended by coordinating, the present invention is described in detail, illustrates as rear:
When LED die bond quality is bad, under passing into same nominal electric current, bad its junction temperature of LED element of die bond can be higher than the normal LED element of die bond quality.Namely the present invention proposes instant detection LED interface method by above-mentioned characteristic, to improve tradition to measure the complicated problem consuming time again of LED thermal resistance value screening LED die bond quality.
Fig. 1 shows the package interface schematic diagram that is assembled in the LED element 10 of circuit board, and wherein LED chip 11 die bond is on package carrier 12, forms die bond interface 13 between its chips 11 and package carrier 12.Die bond interface 13 can comprise as elargol, eutectic alloy or heat-conducting glue etc.LED element 10 comprises chip 11, die bond interface 13 and package carrier 12.Package carrier 12 is assembled on circuit board 15, forms assembling interface 14 therebetween.By this, in fact relevant with the heat radiation of LED chip 11 package interface 16 comprises die bond interface 13 and assembles interface 14.
Measuring principle of the present invention is the characteristic utilizing the forward voltage values of LED can reduce with the rising of LED junction temperature.When LED is passed into this at least one electric current, the PN junction place of LED also can generate heat except luminescence, LED junction temperature just starts to rise, the forward voltage values of LED just starts to reduce rapidly the voltage difference dv (negative value) causing the second forward voltage V2 to deduct the first forward voltage V1 and continues to increase, as shown in Figure 2.Under identical LED chip passes into equal electric current, the ability that the speed that LED forward voltage values declines and institute thermal value are outwards conducted is relevant.When the heat that LED produces outwards conduct be subject to hindering time, LED forward voltage values decline speed can accelerate.That is within identical conduction time, measuring LED energising moment and the forward voltage difference of heat transfer to package interface of LED, the poor LED of outside thermal conduction capability will present larger voltage difference.
Die bond interface bad in LED element encapsulation procedure can screening be out by the measurement of above-mentioned forward voltage difference.Even when LED element is assembled into circuit board or thermal conductive metal plate, the high thermal resistance interface that bad assembling interface is formed also can utilize the measurement of above-mentioned forward voltage difference to carry out screening.
For understanding the detection method of LED interface of the present invention, the pick-up unit of LED interface of the present invention is below described.With reference to Fig. 3, LED interface detection apparatus 20 of the present invention comprises current source 22, voltage check device 23 and unit of testing and controlling 24.In one embodiment, this LED element 25 is equivalent to the LED element 10 shown in Fig. 1.
Fig. 4 shows the flow chart of steps of the detection method of LED interface of the present invention, and detection method of the present invention comprises step S10 provides at least one electric current to this LED element; Step S12 utilizes this at least one electric current to measure one first forward voltage of this LED element in a very first time, and in one second forward voltage of one second this LED element of time measurement; Step S14 calculates the voltage difference of this first and second forward voltage; And step S16 judges that when this voltage difference is greater than a default fail-ure criterion value, then this LED element is judged to lose efficacy.
In following each embodiment, ask common reference Fig. 3 and Fig. 4 in order to pick-up unit and the detection method of understanding LED interface of the present invention.
In first embodiment of the invention as shown in Figure 5, unit of testing and controlling 24 provides at least one control signal S1 command current source 22 to export at least one electric current of at least one test to this LED element 25, and at least twice signal S2 is provided, S3 command voltage pick-up unit 23 measures the forward voltage of this LED element 25, so obtain the first forward voltage V1 respectively at the very first time; The second forward voltage V2 is obtained in the second time.In other words, current source 22 requires to provide at least one test electricity consumption to flow to this LED element according to the control signal S1 of unit of testing and controlling 24, and voltage check device 23 requires according to the signal S2 of unit of testing and controlling 24, S3 these two forward voltages measuring this LED element 25.Notably, the framework of device of the present invention is not limited to disclosed above embodiment framework, and can change according to needed for practical application.
Unit of testing and controlling 24 reads this two forward voltage V1, V2 with this LED element 25 measured by recording voltage pick-up unit 23, the voltage difference of both calculating.Afterwards, unit of testing and controlling 24, according to preset voltage difference fail-ure criterion value, is judged to when being greater than a default fail-ure criterion value to the voltage difference of tested LED element 25 to lose efficacy.
In addition, multiple LED element is taked same test condition (first and second identical time), can differentiate that LED element is lost efficacy (defective products) or effective (non-defective unit), and classify.That is in other embodiments, unit of testing and controlling 24 reads two forward voltage V1 with the multiple LED element 25 measured by recording voltage pick-up unit 23, V2, the voltage difference of both calculating.Afterwards, unit of testing and controlling 24, according to the voltage difference sorted table preset and measured voltage difference, is classified to tested multiple LED element 25, is namely divided into non-defective unit and defective products.
Be at least one electric current of test and the corresponding relation figure of forward voltage and time of second embodiment of the invention please also refer to Fig. 3 and Fig. 4, Fig. 6.Unit of testing and controlling 24 provides at least one control signal S1 command current source 22 to export at least one test electricity consumption and flow to this LED element 25, and at least twice signal S2 is provided, S3 command voltage pick-up unit 23 sequentially measures multiple forward voltages of this LED element 25, the first forward voltage V1 that very first time t1 obtains is contained in, at the second forward voltage V2 that the second time t2 obtains to obtain multiple forward voltage.In other words, current source 22 requires to provide at least one test electricity consumption to flow to this LED element according to the control signal S1 of unit of testing and controlling 24, and voltage check device 23 requires according to the signal S2 of unit of testing and controlling 24, S3 the multiple forward voltages measuring this LED element 25.
In addition, unit of testing and controlling 24 reads the multiple forward voltages with this LED element 25 measured by recording voltage pick-up unit 23, and reads in two forward voltage V1 measured by time t1 and t2 preset, V2, the voltage difference of both calculating.Wherein multiple forward voltage declines along with time remaining, and therefore V1 forward voltage values is greater than V2 forward voltage values.Afterwards, unit of testing and controlling 24 according to preset voltage difference fail-ure criterion value, to test this LED element 25 voltage difference be greater than fail-ure criterion value time be judged to lose efficacy.
The voltage difference fail-ure criterion value preset decides according to the chip of LED element and the interval td of encapsulating structure and two Measuring Time.If the encapsulating structure heat conduction of LED element is poor will measure larger voltage difference.Similarly, for having the LED element of identical chips structure and encapsulating structure, the interval td of two Measuring Time is longer, and voltage difference also can be larger.The forward voltage difference that Fig. 7 shows 20 LED element increases and the experiment measuring figure of increase with passing into current time.According to the second embodiment describe, provide at least one electric current 350 milliampere to LED element, voltage check device sequentially measures multiple forward voltages of LED element.After at least one electric current exports 20 microseconds, the first forward voltage V1 is measured to, the curve that whole voltage differences subtracts the first forward voltage V1 by other forward voltages (being later than the first forward voltage V1) and obtains as shown in Figure 7.The time t1 preset in this experiment is that electric current exports 20 microseconds, when the time t2 preset be electric current export 0.1 second time the second forward voltage V2 be measured to, now preset voltage difference fail-ure criterion value and be then set as 200 millivolts, if the voltage difference of LED element is greater than when presetting voltage difference fail-ure criterion value, LED element is then judged as losing efficacy.Moreover, if when the time t2 preset be electric current export 5 seconds time the second forward voltage V2 be measured to, now preset voltage difference fail-ure criterion value and be then set as 250 millivolts.Therefore, application the present invention in LED interface detect with defective products screening before, can reference example two and this description of test, the voltage difference fail-ure criterion value that setting is applicable to.
In first and second embodiment, the test electric current exported by current source 22 can be pulse current or DC current, and test current value can, according to the configuration settings of LED element 25, adopt the rated current of LED element 25 as test electric current usually.The load current value with the LED element 25 of the LED chip area of 1 square millimeter can be between 250 milliampere to 350 milliamperes.In addition, if the load current value with the LED element 25 of the LED chip area of 0.1 square millimeter can be between 10 milliampere to 20 milliamperes.Moreover td interval time of voltage measurement determines according to the structure of test electric current and LED element 25 or pattern, generally speaking interval time, td was between 100 microseconds to 1 second.But the present invention is not limited to the every data in the first embodiment and the second embodiment.
In the third embodiment of the present invention as shown in Figure 8, unit of testing and controlling 24 provides one first control signal S1 command current source 22 to export a test electricity consumption and flow to this LED element 25, and provides signal S2 command voltage pick-up unit 23 to measure the forward voltage V1 of this LED element 25.Then unit of testing and controlling 24 provides one second control signal S1 ' command current source 22 to export a heating electric and flow to this LED element 25.After a heat-up periods time th, unit of testing and controlling 24 provides one the 3rd control signal S1, and " command current source 22 stops heating electric stream and starts to export test electric current.Unit of testing and controlling 24 provides a signal S3 command voltage pick-up unit 23 to measure the forward voltage V2 of this LED element 25 in the second time t2 simultaneously.
Then, this unit of testing and controlling 24 reads this two voltage V1, V2 with this LED element 25 measured by recording voltage pick-up unit 23, and the voltage difference both calculating.Afterwards, unit of testing and controlling 24 according to preset voltage difference fail-ure criterion value, to test this LED element 25 voltage difference be greater than fail-ure criterion value time be judged to lose efficacy.
In the third embodiment, the test electric current exported by current source 22 can be the pulse current of pulse width 20 microsecond to 100 microsecond, and test current value is according to the configuration settings of LED element 25.The test current value adopted in this embodiment can be between 0.1 milliampere to 5 milliampere.The heating electric stream exported by current source 22 can be pulse current or DC current, and heating electric flow valuve is according to the configuration settings of LED element 25.The load current value of usual employing LED element 25 is as heating electric stream.Heat-up periods time th determines according to the structure of test current value and LED element 25 or pattern, and generally speaking heat-up periods time th is between 100 microseconds to 1 second.Compared to the first embodiment, the test current value in the 3rd embodiment is less, therefore can avoid the measuring error that the additional heat produced by big current causes.
In the same manner, comprise voltage V1 and V2 in the 4th embodiment in order to obtain multiple forward voltage in different time, as shown in Figure 9, current source 22 alternatively provides test electric current and heating electric to flow to LED element 25.Unit of testing and controlling 24 provides at least two signal S2, and S3 command voltage pick-up unit 23 measures multiple forward voltages of this LED element 25 in order with this test electric current.
Unit of testing and controlling 24 reads with multiple forward voltage of the LED element 25 measured by recording voltage pick-up unit 23 and reads in two forward voltage V1 measured by time t1 and t2 preset, V2, and the voltage difference both calculating.Wherein these forward voltages decline along with time remaining, and forward voltage values V1 is greater than forward voltage values V2.Then unit of testing and controlling 24 is according to preset voltage difference fail-ure criterion value, is judged to lose efficacy when being greater than fail-ure criterion value to the voltage difference of tested LED element 25.
In the fifth embodiment of the present invention as shown in Figure 10, unit of testing and controlling 24 provides one first control signal S1 command current source 22 to export one first test electricity consumption and flow to this LED element 25, and provides signal S2 command voltage pick-up unit 23 to measure the forward voltage V1 of this LED element 25.Then unit of testing and controlling 24 provides the second control signal S1 ' command current source 22 to export one second test electricity consumption and flow to this LED element 25, and provides a signal S3 command voltage pick-up unit 23 to measure the forward voltage V2 of this LED element 25.In this embodiment, the first test electric current and the second test electric current can be pulse current, and the first test current value and the second test current value equal with the load current value of this LED element 25.As shown in Figure 10, the pulse width of the first test electric current is between 20 microsecond to 100 microseconds, and the pulse width of the pulse width ratio first test electric current of the second test electric current is large.The pulse width of the second test electric current is between 100 microseconds to 1 second, and the junction temperature of this LED element 25 can be caused to rise, and forward voltage declines.
Unit of testing and controlling 24 reads the forward voltage (V1 and V2) with the LED element 25 measured by recording voltage pick-up unit 23, and the voltage difference both calculating.Then unit of testing and controlling 24 is according to preset voltage difference fail-ure criterion value, is judged to lose efficacy when being greater than fail-ure criterion value to the voltage difference of tested LED element 25.
In the same manner, in order to obtain multiple forward voltage in different time in 6th embodiment, as shown in figure 11, unit of testing and controlling 24 provide multiple control signal command current source 22 export have pulse width broaden gradually characteristic pulsed test electricity consumption flow to LED element 25 and provide multiple signal command voltage check device 23 to measure multiple forward voltages of this LED element 25 in order.Increase due to pulse width is risen by the junction temperature of this LED element 25 in time, that is the forward voltage of this LED element 25 declines in time.
Unit of testing and controlling 24 reads with multiple forward voltage of the LED element 25 measured by recording voltage pick-up unit 23 and reads in two forward voltage V1 measured by time t1 and t2 preset, V2, and the voltage difference both calculating.Wherein these forward voltages decline along with time remaining, and forward voltage values V1 is greater than forward voltage values V2.Then unit of testing and controlling 24 is according to preset voltage difference fail-ure criterion value, is judged to lose efficacy when being greater than fail-ure criterion value to the voltage difference of tested LED element 25.
In addition, the lower general who has surrendered of LED junction temperature causes the rising of LED forward voltage.After this LED element being inputted to the heating electric stream of a period of time, stop heating electric stream, use multiple forward voltages that at least one test electric current (such as having the pulse current of short pulse width) measures LED element in order instead.In the case, the forward voltage of LED element rise fast so that forward voltage difference dv (on the occasion of) can increase in time.Particularly, this LED element with bad package interface is by than there being the LED element of well packaged interface quality to demonstrate larger forward voltage difference.
In the seventh embodiment of the present invention as shown in figure 12, unit of testing and controlling 24 provides one first control signal S1 command current source 22 to export a heating electric and flow to this LED element 25.After heating current exports a heat-up periods time th, unit of testing and controlling 24 provides a signal S2 command voltage pick-up unit 23 to measure the forward voltage V1 of this LED element 25, and provides one second control signal S1 ' command current source 22 to stop exporting heating electric stream.Then unit of testing and controlling 24 provides the 3rd control signal S1, and " command current source 22 exports a test electricity consumption with short pulse width an interval time and flow to this LED element 25 after td, and provides a signal S3 command voltage pick-up unit 23 to measure the forward voltage V2 of this LED element 25.As shown in figure 12, test current value and heating electric flow valuve equal with the load current value of LED element 25.The pulse width of test electric current is between 20 microsecond to 100 microseconds.
Unit of testing and controlling 24 reads the forward voltage (as V1 and V2) with the LED element 25 measured by recording voltage pick-up unit 23, and the voltage difference both calculating.Then unit of testing and controlling 24 is according to preset voltage difference fail-ure criterion value, is judged to lose efficacy when being greater than fail-ure criterion value to the voltage difference of tested LED element 25.Because LED element 25 to be heated in heat-up periods time th by heating electric stream and is measured by the test electricity consumption stream with short pulse width, the junction temperature of LED element 25 will decline after heat-up periods time th and its voltage difference measured will on the occasion of.
In the same manner, in order to obtain multiple forward voltage in different time in 8th embodiment, as shown in figure 13, after heating electric stream stops, the test electricity consumption that unit of testing and controlling 24 provides multiple control signal command current source 22 to export short pulse width in order flow to LED element 25 and provides multiple signal command voltage check device 23 to measure the forward voltage of LED element 25 in order.Current source 22 exports heating electric and flow to LED element 25 during heat-up periods time th.The junction temperature of LED element 25 starts to decline after heat-up periods time th, and forward voltage starts to rise.As shown in figure 13, the pulse width of test electric current is between 20 microsecond to 100 microseconds.Test current value and heating electric flow valuve equal with the load current value of LED element 25.
Unit of testing and controlling 24 reads with multiple forward voltage of the LED element 25 measured by recording voltage pick-up unit 23 and reads in two forward voltage V1 measured by time t1 and t2 preset, V2, and the voltage difference both calculating.Wherein these forward voltages rise along with time remaining, and forward voltage values V1 is less than forward voltage values V2.Then unit of testing and controlling 24 is according to preset voltage difference fail-ure criterion value, is judged to lose efficacy when being greater than fail-ure criterion value to the voltage difference of tested LED element 25.
In the ninth embodiment of the present invention as shown in figure 14, unit of testing and controlling 24 provides one first control signal S1 command current source 22 to export a heating electric and flow to this LED element 25.After heat-up periods time th, unit of testing and controlling 24 provides one second control signal S1 ' command current source 22 to stop exporting heating electric stream, and " command current source 22 exports test electricity consumption and flow to this LED element 25 to provide the 3rd control signal S1.Then unit of testing and controlling 24 provides signal S2 command voltage pick-up unit 23 to measure the forward voltage V1 of this LED element 25.Unit of testing and controlling 24 provides the 4th control signal S1, and " ' command current source 22 exports test electric current interval time after td, and provides signal S3 command voltage pick-up unit 23 to measure the forward voltage V2 of this LED element 25.
Unit of testing and controlling 24 reads two forward voltages (as V1 and V2) with the LED element 25 measured by recording voltage pick-up unit 23, and the voltage difference both calculating.Then unit of testing and controlling 24 is according to preset voltage difference fail-ure criterion value, is judged to lose efficacy when being greater than fail-ure criterion value to the voltage difference of tested LED element 25.Because LED element 25 is heated by heating electric stream and is measured by the test electricity consumption stream with short pulse width during heat-up periods time th, the junction temperature of LED element 25 will decline after heat-up periods time th and its voltage difference measured will on the occasion of.In this embodiment, heating electric flow valuve is equal with the load current value of LED element 25.Test current value between 0.1 milliampere to 5 milliampere, to reduce the issuable thermal effect of big current.The pulse width of test electric current is between 20 microsecond to 100 microseconds.But the present invention is not limited to the condition described in this embodiment.
In the same manner, in order to obtain multiple forward voltage in different time in tenth embodiment, as shown in figure 15, after heating electric stream has stopped exporting, unit of testing and controlling 24 provides multiple control signal command current source 22 to export current in short bursts in order to LED element 25 provides multiple signal command voltage check device 23 to measure multiple forward voltages of this LED element 25 in order.Current source 22 exports heating electric and flow to this LED element 25 in heat-up periods time th.After heat-up periods time th, the junction temperature of this LED element 25 declines, and forward voltage starts to rise.
Unit of testing and controlling 24 reads multiple forward voltage of the LED element 25 measured after heat-up periods time th with recording voltage pick-up unit 23 and reads in two forward voltage V1 measured by time t1 and t2 preset, V2, and the voltage difference both calculating.Wherein these forward voltages rise along with time remaining, and forward voltage values V1 is less than forward voltage values V2.Then unit of testing and controlling 24 is according to preset voltage difference fail-ure criterion value, is judged to lose efficacy when being greater than fail-ure criterion value to the voltage difference of tested LED element 25.
In foregoing individual embodiments, this LED element 25 is flow to when unit of testing and controlling 24 provides control signal command current source 22 to export test electricity consumption, and when providing signal command voltage check device 23 to measure the forward voltage of LED element 25, a time delay can be set to reduce voltage measurement error before voltage measurement.Time delay is between 5 microsecond to 50 microseconds.The td and heat-up periods time th interval time of voltage measurement determines according to the structure of test current value and LED element 25 or pattern.Generally speaking, interval time, td and heat-up periods time th was between 100 microseconds and between 1 second.But the present invention is not as limit.The voltage check device 23 that pick-up unit 20 of the present invention uses is one fast and high-res voltage check device, and its voltage resolution should be less than 5mV, best for being less than 0.2mV, but the present invention is not as limit; Sampling rate is per second should higher than 200,000 times, and best is per second sampling 1,000,000 times, but the present invention is not as limit.
The present invention further provides the computer program of a detection LED element, it comprises the computer read/write memory medium that contains a computer-readable medium instruction, and this computer-readable medium instruction comprises to give an order: the first instruction provides at least one electric current to this LED element; Second instruction utilize this electric current in a very first time measure this LED element one first forward voltage and in one second forward voltage of one second this LED element of time measurement; 3rd command calculations this first and a voltage difference of this second forward voltage; And the 4th instruction judge when this voltage difference be greater than one preset fail-ure criterion value time, then this LED element be judged to be inefficacy.
When the package interface of multiple LED element detects, unit of testing and controlling 24 can carry out the height classification of LED element 25 according to the voltage difference of multiple LED.Figure 16 shows the flow chart of steps of the detection method of another embodiment of the present invention LED interface.The detection method of this LED interface comprises step S20 provides at least one electric current; Step S22 utilizes this electric current to measure the first forward voltage of the plurality of LED element in a very first time, and in the second forward voltage of the plurality of LED element of one second time measurement; Step S24 calculates the voltage difference of this first and second forward voltage; And step S26 classifies to multiple LED element according to the plurality of voltage difference.This very first time of wherein measuring each this LED element is equal, and this second time of measuring each this LED element is equal.
The present invention proposes one LED interface detection method and device fast.LED is passed into pulse current or the DC current of a bit of time, measure one first forward voltage of this LED element in a very first time simultaneously, and in one second forward voltage of one second this LED element of time measurement, calculate the voltage difference of the first forward voltage and the second forward voltage, by the difference of more each LEDs forward voltage difference and the quality of distinguishable LED die bond quality.Because the time needed for detection of the present invention only needs several microsecond, therefore be combined with general LED Quick photoelectric Characteristics Detection machine, can the screening of quick die bond defective products on LED element dispatches from the factory advance line.
Below the present invention is described in detail, but the foregoing is only preferred enforcement example of the present invention, when not limiting scope of the invention process.Namely the equalization that all scopes claimed according to claims of the present invention are done changes and modifies, and all should still belong in the claimed scope of claims of the present invention.
Claims (35)
1. the pick-up unit of a LED package interface, it need not measure the thermal resistance value of a LED element, but utilize die bond interface or assembling interface bad time this LED element the characteristic that forward voltage values can reduce with the rising of the junction temperature of this LED element or forward voltage values can rise with the reduction of the junction temperature of this LED element, this LED element with a package interface is detected, comprises:
One current source;
One voltage check device; And
One unit of testing and controlling, at least one this current source of control signal order is provided to export at least one electric current to this LED element, and at least binary signal is provided, this voltage check device is ordered to utilize this at least one electric current to measure one first forward voltage of this LED element in a very first time respectively, and in one second forward voltage of one second this LED element of time measurement;
Wherein this unit of testing and controlling calculate this first and the voltage difference of this second forward voltage, and judge when this voltage difference is greater than a default fail-ure criterion value, then this LED element is judged to lose efficacy, wherein, this default fail-ure criterion value decides according to the interval of two Measuring Time of this very first time and this second time;
Wherein this die bond interface is formed between a LED chip and a package carrier;
This assembling interface is formed between this package carrier and a circuit board.
2. the pick-up unit of LED interface as claimed in claim 1, wherein this at least one electric current is a test electric current, this current source sequentially provides this test electricity consumption to flow to this LED element and this voltage check device measures multiple forward voltages of this LED element in order, comprising this first forward voltage measuring this LED element in this very first time, at this second forward voltage of this this LED element of the second time measurement.
3. the pick-up unit of LED interface as claimed in claim 2, wherein this current source exports the rated current that this test current value of this LED element is this LED element.
4. the pick-up unit of LED interface as claimed in claim 1, wherein the interval time of this very first time and this second time is between 100 microseconds (μ sec) to 1 second (sec).
5. the pick-up unit of LED interface as claimed in claim 1, wherein this at least one electric current comprises at least one test electric current and a heating electric stream, this at least one test current value is between 0.1 milliampere (mA) to 5 milliamperes, this heating electric flow valuve is equal with a load current value of this LED element, this current source exports this at least one test electricity consumption respectively at the time period comprising this very first time with another time period comprising this second time and flow to this LED element, the heat-up periods time before this second time, this current source exports this heating electric and flow to this LED element, this heat-up periods time is between 100 microseconds to 1 second.
6. the pick-up unit of LED interface as claimed in claim 1, wherein this current source alternatively exports at least one test electric current and at least one heating electric flow to this LED element, this voltage check device measures multiple forward voltages of this LED element in order with this at least one test electric current, comprising in this very first time, when this test electric current exports this LED element to, measure this first forward voltage, in this second time, when this test electric current exports this LED element to, measure this second forward voltage.
7. the pick-up unit of LED interface as claimed in claim 1, wherein this at least one electric current comprises one first test electric current and one second test electric current, this current source exports this first test electric current respectively at the time period comprising this very first time and another time period of comprising this second time and this second test electricity consumption flow to this LED element, this the first test electric current and this second test electric current are pulse current, the pulse width of this second test electric current is large compared with the pulse width of this first test electric current, this the first test current value and this second test current value equal with a load current value of this LED element.
8. the pick-up unit of LED interface as claimed in claim 1, wherein this at least one electric current comprises multiple test electric current, the plurality of test electric current is pulse current and little by little increases pulse width, this current source provides the plurality of test electricity consumption to flow to this LED element in order and this voltage check device measures multiple forward voltages of this LED element in order with the plurality of test electric current, comprising this first forward voltage measuring this LED element in this very first time, at this second forward voltage of this this LED element of the second time measurement, the plurality of test current value is equal with a load current value of this LED element.
9. the pick-up unit of LED interface as claimed in claim 1, wherein this at least one electric current comprises a heating electric stream and a test electric current, this current source is until export this heating electric and flow to this LED element and export this test electricity consumption in the time period comprising this second time and flow to this LED element before this very first time in the heat-up periods time comprising this very first time, wherein this heating electric stream and this test electric current are pulse current, the pulse width of this heating electric stream is large compared with the pulse width of this test electric current, this heating electric flow valuve and this test current value equal with a load current value of this LED element, and the interval time of this very first time and this second time is between 100 microseconds to 1 second.
10. the pick-up unit of LED interface as claimed in claim 1, wherein this at least one electric current comprises a heating electric stream and multiple test electric current, this current source provides this heating electric stream and the plurality of test electricity consumption to flow to this LED element in order, this voltage check device measures multiple forward voltages of this LED element in order with the plurality of test electric current, this first forward voltage of this LED element is measured in this very first time, at this second forward voltage of this this LED element of the second time measurement, wherein this heating electric stream and the plurality of test electric current are pulse current, the pulse width of this heating electric stream is large compared with the pulse width of the plurality of test electric current, this heating electric flow valuve and the plurality of test current value equal with a load current value of this LED element.
The pick-up unit of 11. LED interfaces as claimed in claim 1, wherein this at least one electric current comprises a heating electric stream and at least one test electric current, this at least one test current value is less than this heating electric flow valuve, this electric current exports this heating electric in the heat-up periods time before coming from this very first time and flow to this LED element and export this at least one test electricity consumption in the time period comprising this very first time and another time period comprising this second time respectively and flow to this LED element, wherein this heating electric flow valuve is equal with a load current value of this LED element, this at least one test current value is between 0.1 milliampere to 5 milliampere, and the interval time of this very first time and this second time is between 100 microseconds to 1 second.
The pick-up unit of 12. LED interfaces as claimed in claim 11, wherein this current source provides this at least one test electricity consumption to flow to this LED element in order, this voltage check device measures multiple forward voltages of this LED element in order with this at least one test electric current, this first forward voltage of this LED element is measured, at this second forward voltage of this this LED element of the second time measurement in this very first time.
The pick-up unit of 13. LED interfaces as claimed in claim 1, wherein this LED element comprises this LED chip and this package carrier.
The pick-up unit of 14. LED interfaces as claimed in claim 13, wherein this LED element also comprises this circuit board.
The pick-up unit of 15. LED interfaces as claimed in claim 1, wherein the resolution of this voltage check device is less than 5 millivolts (mV), and sampling rate is per second higher than 200,000 times.
The detection method of 16. 1 kinds of LED interfaces, it need not measure the thermal resistance value of a LED element, but utilize die bond interface or assembling interface bad time this LED element the characteristic that forward voltage values can reduce with the rising of the junction temperature of this LED element or forward voltage values can rise with the reduction of the junction temperature of this LED element, detect for this LED element with a package interface, the method includes the steps of:
There is provided at least one electric current to this LED element;
This at least one electric current is utilized to measure one first forward voltage of this LED element in a very first time, and in one second forward voltage of one second this LED element of time measurement;
Calculate this first and a voltage difference of this second forward voltage; And
Judge when this voltage difference be greater than one preset fail-ure criterion value time, then this LED element is judged to be inefficacy, and wherein, this default fail-ure criterion value decides according to the interval of two Measuring Time of this very first time and this second time;
Wherein this die bond interface is formed between a LED chip and a package carrier;
This assembling interface is formed between this package carrier and a circuit board.
The detection method of 17. LED interfaces as claimed in claim 16, wherein this at least one electric current is a test electric current, utilize this at least one electric current to measure multiple forward voltages of this LED element in order, the plurality of forward voltage of this LED element comprises this first forward voltage and this second forward voltage.
The detection method of 18. LED interfaces as claimed in claim 17, wherein this current value is equal with a load current value of this LED element.
The detection method of 19. LED interfaces as claimed in claim 16, wherein the interval time of this very first time and this second time is between 100 microseconds to 1 second.
The detection method of 20. LED interfaces as claimed in claim 16, wherein this at least one electric current comprises at least one test electric current and a heating electric stream, this at least one test current value is between 0.1 milliampere (mA) to 5 milliamperes, this heating electric flow valuve is equal with a load current value of this LED element, the time period comprising this very first time with comprise another time period of this second time and provide this at least one test electricity consumption to flow to this LED element, the heat-up periods time before this second time provides this heating electric to flow to this LED element, this heat-up periods time is between 100 microseconds to 1 second.
The detection method of 21. LED interfaces as claimed in claim 20, wherein this at least one test electric current and this heating electric stream are alternatively provided to this LED element, utilize this at least one test electric current to measure multiple forward voltages of this LED element in order, the plurality of forward voltage of this LED element comprises this first forward voltage and this second forward voltage.
The detection method of 22. LED interfaces as claimed in claim 16, wherein this at least one electric current comprises one first test electric current and one second test electric current, this the first test electric current is a pulse current and is provided to this LED element in the time period comprising this very first time, this the second test electric current is a pulse current and is provided to this LED element in another time period comprising this second time, the pulse width of this second test electric current is large compared with the pulse width of this first test electric current, this the first test current value and this second test current value equal with a load current value of this LED element.
The detection method of 23. LED interfaces as claimed in claim 16, wherein this at least one electric current comprises multiple test electric current, the plurality of test electric current is pulse current and little by little increases pulse width, the plurality of test electric current is utilized to measure multiple forward voltages of this LED element in order, the plurality of forward voltage of this LED element comprises this first forward voltage and this second forward voltage, and the plurality of test current value is equal with a load current value of this LED element.
The detection method of 24. LED interfaces as claimed in claim 16, wherein this at least one electric current comprises a heating electric stream and a test electric current, thered is provided this heating electric to flow to this LED element in the heat-up periods time comprising this very first time and provide this test electricity consumption to flow to this LED element in the time period comprising this second time before this very first time, wherein this test electric current and this heating electric stream are pulse current, the pulse width of this heating electric stream is large compared with the pulse width of this test electric current, this heating electric flow valuve and this test current value equal with a load current value of this LED element, and the interval time of this very first time and this second time is between 100 microseconds to 1 second.
The detection method of 25. LED interfaces as claimed in claim 16, wherein this at least one electric current comprises a heating electric stream and multiple test electric current, this current source provides this heating electric stream and the plurality of test electricity consumption to flow to this LED element in order, one voltage check device measures multiple forward voltages of this LED element in order with the plurality of test electric current, the plurality of forward voltage of this LED element comprises this first forward voltage and this second forward voltage, wherein this heating electric stream and the plurality of test electric current are pulse current, the pulse width of this heating electric stream is large compared with the pulse width of the plurality of test electric current, this heating electric flow valuve and the plurality of test current value equal with a load current value of this LED element.
The detection method of 26. LED interfaces as claimed in claim 16, wherein this at least one electric current comprises a heating electric stream and at least one test electric current, this at least one test current value is less than this heating electric flow valuve, this heating electric is provided to flow to this LED element in the heat-up periods time before this very first time, the time period comprising this very first time with comprise another time period of this second time and provide this at least one test electricity consumption to flow to this LED element, wherein this heating electric flow valuve is equal with a load current value of this LED element, this at least one test current value is between 0.1 milliampere to 5 milliampere, and the interval time of this very first time and this second time is between 100 microseconds to 1 second.
The detection method of 27. LED interfaces as claimed in claim 26, this at least one test electricity consumption is wherein provided to flow to this LED element in order, utilize this at least one test electric current to measure multiple forward voltages of this LED element in order, the plurality of forward voltage of this LED element comprises this first forward voltage and this second forward voltage.
The detection method of 28. LED interfaces as claimed in claim 16, wherein this LED element comprises this LED chip and this package carrier.
The detection method of 29. LED interfaces as claimed in claim 28, wherein this LED element also comprises this circuit board.
The detection method of 30. 1 kinds of multiple LED interfaces, it need not measure the thermal resistance value of a LED element, but utilize die bond interface or assembling interface bad time this LED element the characteristic that forward voltage values can reduce with the rising of the junction temperature of this LED element or forward voltage values can rise with the reduction of the junction temperature of this LED element, detect for this LED element with a package interface, the method includes the steps of:
At least one electric current is provided;
This at least one electric current is utilized to measure one first forward voltage of each LED element in a very first time, and in one second forward voltage of one second each LED element of time measurement;
Calculate each LED element this first and a voltage difference of this second forward voltage; And
To classify the plurality of LED element according to this voltage difference of each the plurality of LED element,
Wherein, this voltage difference decides according to the interval of two Measuring Time of this very first time and this second time;
Wherein this die bond interface is formed between a LED chip and a package carrier;
This assembling interface is formed between this package carrier and a circuit board.
The detection method of 31. multiple LED interfaces as claimed in claim 30, this very first time of wherein measuring each the plurality of LED element is equal, and this second time of measuring this each LED element is equal.
32. 1 kinds for detecting the device of LED interface, it need not measure the thermal resistance value of a LED element, but utilize die bond interface or assembling interface bad time this LED element the characteristic that forward voltage values can reduce with the rising of the junction temperature of this LED element or forward voltage values can rise with the reduction of the junction temperature of this LED element, detect for this LED element with a package interface, this device comprises:
For providing at least one electric current to the module of this LED element;
The module of one first forward voltage of this LED element one second forward voltage in one second this LED element of time measurement is measured in a very first time for utilizing this at least one electric current;
For calculate this first and the module of a voltage difference of this second forward voltage; And
For judge when this voltage difference be greater than one preset fail-ure criterion value time, then this LED element is judged to be the module of inefficacy, and wherein, this default fail-ure criterion value decides according to the interval of two Measuring Time of this very first time and this second time;
Wherein this die bond interface is formed between a LED chip and a package carrier;
This assembling interface is formed between this package carrier and a circuit board.
33. devices as claimed in claim 32, wherein this at least one electric current is a long duration current, utilize this at least one electric current to measure multiple forward voltages of this LED element in order, the plurality of forward voltage of this LED element comprises this first forward voltage and this second forward voltage.
34. devices as claimed in claim 33, wherein this at least one current value is equal with a load current value of this LED element.
35. devices as claimed in claim 32, wherein the interval time of this very first time and this second time is between 100 microseconds to 1 second.
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| US12/823,859 US20110133769A1 (en) | 2009-12-09 | 2010-06-25 | Inspection apparatus and method for led package interface |
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| CN102693925B (en) * | 2011-03-25 | 2016-05-25 | 夏普株式会社 | The temperature characterisitic testing fixture of semiconductor light-emitting elements and temperature characterisitic inspection method |
| CN107797499B (en) * | 2017-11-30 | 2023-10-31 | 佛山科学技术学院 | Pulse type program-controlled power supply and control method |
| CN111965515B (en) * | 2020-10-21 | 2021-01-19 | 深圳市永联科技股份有限公司 | Method for identifying fault of reverse-filling prevention diode |
| CN112858887A (en) * | 2021-01-18 | 2021-05-28 | 昂宝电子（上海）有限公司 | Layered defect detection method for integrated circuit package |
| CN113985242A (en) * | 2021-11-10 | 2022-01-28 | 扬州虹扬科技发展有限公司 | Screening method of diode crystal grain welding qualified product |
| CN114664704A (en) * | 2022-03-18 | 2022-06-24 | 东莞市中麒光电技术有限公司 | LED chip screening method and display screen |
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