CN102255033A - High-power LED (Light-Emitting Diode) encapsulating structure and encapsulating method - Google Patents
High-power LED (Light-Emitting Diode) encapsulating structure and encapsulating method Download PDFInfo
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- CN102255033A CN102255033A CN2011101966684A CN201110196668A CN102255033A CN 102255033 A CN102255033 A CN 102255033A CN 2011101966684 A CN2011101966684 A CN 2011101966684A CN 201110196668 A CN201110196668 A CN 201110196668A CN 102255033 A CN102255033 A CN 102255033A
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Abstract
The invention discloses a high-power LED encapsulating structure, which is characterized by having a welding flux die bonding structure, wherein a welding flux is a low-temperature lead-free welding flux. The high-power LED encapsulating structure has the advantages of high heat conductivity, long service life, energy saving and environmental friendliness. By adopting the high-power LED encapsulating structure, the problems of low heat conducting efficiency, high heat resistance, poor stress resistance, high attenuation, over high cost, short service life and the like existing in the prior art can be solved.
Description
Technical field
The present invention relates to a kind of high-power LED encapsulation structure and method for packing thereof, high-power LED encapsulation structure and method for packing thereof that particularly a kind of frame bottom is a metal level.
Background technology
Along with industry constantly develops, the great power LED light efficiency is more and more higher, and luminous flux is also more and more higher, but how the heat that led chip produces derive fast, reduces the thermal resistance between chip and the framework, so far solution preferably not still in the industry cycle.In existing great power LED is made; the crystal-bonding adhesive employing elargol and the white glues of wafer are more; therefore the conductive coefficient of two kinds of materials is relatively poor; Gu brilliant back thermal resistance is bigger; so that for a long time under the operating position; easy to change and heat conductivility variation; the result who causes is that the heat that the led chip heating produces can't in time be discharged; make chip protection glue on every side at high temperature work this for a long time; easily aging yellowing blackening; thereby make the product light decay become big lifetime, can not give play to long, the non-maintaining benefit of real life-span of LED.
Big merit LED adopts the solid crystal type of elargol, can improve the thermal conductivity between chip and the support, but the Main Ingredients and Appearance of elargol is silver powder and epoxy resin, heat conduction is finished by the transmission between silver powder and the silver powder, and the granular size of silver powder, the consistency of particle, the cavity between particle and the grain, and the binding epoxy resin between particle and the particle, all can cause control transfer of heat to reduce at double; Present stage, general employing improved the content ratio of silver powder in the elargol, but improves after the content of silver powder in order to improve the thermal conductivity of elargol, and can produce following problem: poor operability, poor plasticity, price obviously increase, storage condition requirement height.Even but after the ratio of silver powder brings up to certain ratio, increase can not be arranged again, otherwise can't use.Existing ratio mode by increase silver powder also can only be brought up to 28W/mk with conductive coefficient, and this parameter that to be the supplier provide, and in LED manufacturer, because of the thickness of separately process conditions, working condition, preservation condition, elargol etc., the conductive coefficient of product is reduced at double, thereby the heat that led chip is produced can't be derived, again because of containing epoxy resin in the elargol, at high temperature, the easy flavescence of epoxy resin, thereby cause brightness decay, and the temperature around the chip improves constantly, thereby make the lifetime of product.
Great power LED adopts white glues solid brilliant, can improve the luminous efficiency of LED, original intensity is than higher, but because white glues generally adopts epoxy resin or silicon materials preferably, has temperature tolerance preferably, but conductive coefficient is lower, only less than 3W/mk, but can't derive as the heat that fruit chip produces, LED at high temperature uses for a long time can produce following problem: chip is burnt, uses the flavescence blackening to make brightness decay become big because of the characteristic relation between the temperature current voltage of semiconductor product makes properties of product variation, chip glue all around because of long-time.
Have better heat conductivity coefficient and shearing after the tin cream welding, but adopt tin cream as wafer fixedly material have following problem, the composition of tin cream is mainly the powder of metal objects such as Sn, Ag, Cu, Pb, Bi, must its one-tenth be become paste by scaling powder could use, in welding process, scaling powder fusion volatilization causes chip to pollute easily, causes the gold thread welding quality problems such as rosin joint to occur; And tin cream can expand in fusion processes, flow, and causes the chip displacement, tilts, and easily causes serious quality such as inclined to one side weldering, rosin joint bad in follow-up gold thread welding process; Tin cream produces very big stress, fragile chip in fusion and cooling procedure; And the chip displacement can cause causing phenomenons such as luminance nonuniformity behind the encapsulation finished product.
Summary of the invention
The purpose of this invention is to provide a kind of high-power LED encapsulation structure and method for packing thereof, problems such as it can solve, and heat transfer efficiency is poor in the prior art, thermal resistance is big, anti-stress ability, decay is bigger than normal, cost is too high, the life-span is short and the quality that produces with tin cream production is bad.
For this reason, according to an aspect of the present invention, provide a kind of high-power LED encapsulation structure, adopted scolder solid brilliant, scolder is a low-temperature lead-free solder.
Preferably, scolder can be SnSbAgNi.
Preferably, when adopting scolder brilliant admittedly, adopt the segmentation heating.
Preferably, bottom of wafer is coated with metal level.
According to another aspect of the present invention, provide a kind of high-power LED packaging method, comprised the steps: the heat conduction solder dots in the middle of the metal heat-conducting layer of support, it to be fused by certain temperature; Chip is placed on the heat conduction scolder of fusion bondingly, after the cooling, die bonding is on scolder; Connect by the both positive and negative polarity of gold thread wafer; With fluorescent material point on wafer.
Segmentation heating when preferably, fusing scolder.
Preferably, chip is placed on the heat conduction scolder of fusion when bonding, uses chip friction scolder, to reduce the cavity in the scolder.
Preferably, obtain smooth surface after the scolder fusion.
According to the present invention, can solve the scarce limit of the indeterminable heat-resisting and poor heat conductivity of elargol and white glues from key, reduce thermal resistance, thereby promote the life-span of LED product, reach high temperature resistant, low decay, long-lived purpose.
Description of drawings
Fig. 1 a, Fig. 1 b and Fig. 1 c are the process chart of method for packing of the present invention.
Embodiment
Below in conjunction with embodiment, the present invention is carried out detailed explanation.
At first, analyze the heat conduction problem that exists in the prior art, the medium of existing LED between from the chip to the support is elargol or white glues, the eutectic of employing mode is also arranged, the conductive coefficient of elargol is generally 2-3W/mk in the existing product, super your elargol of special process also can only reach 20-30W/mk; The conductive coefficient of white glues is no more than 3W/mk; The eutectic mode reaches more than 350 degree because of temperature required, to product quality reliably have certain threat, eutectic produces very big internal stress simultaneously, does not have cushion between chip and the framework, chip is easy to be subjected to stress damage.To this, the present invention will adopt scolder to carry out solid crystalline substance, and conductive coefficient reaches more than the 50W/mk, and adhesion is much larger than elargol and white glues, and internal stress is far smaller than eutectic, and temperature is lower when producing, and only needs a 260-320 degree to use.
The scolder mode that this programme adopts substitutes solid brilliant elargol and white glues, and that the mode of scolder is used in the triode aspect is more general, but using is to belong to initiative on LED, its technology and triode have bigger difference: the composition of three utmost points is mainly leaded in the solder component, do not allow solder containing pb in the LED product, therefore, need the novel scolder that is suitable for LED of research and development; The triode support is a simple metal, and led support contains plastic cement, therefore needs cryogenic material and low temperature process; Scolder is used in also has reflection function on the LED, need corresponding technology to guarantee its reflecting rate; Though LED and other semiconductor type, but LED also belongs to the photoelectricity subclass simultaneously, other semiconductor is mainly paid close attention to electricity, and LED mainly pays close attention to optics, LED more is output, light efficiency, brightness decay, the brightness height of luminous flux etc., it has fixing measuring current, mainly measures voltage parameter and optical parametric by constant current.And unlike the output of the electric current of other semiconductor type what, withstand voltage what etc., multiplying power amplify what etc.; The present invention mainly is the breakthrough on the LED product.
Have the following advantages after adopting the LED scolder to substitute elargol and white glues: thermal conductivity increases, and the direct benefit of the increase of thermal conductivity is the thermal resistance step-down of LED, and the reduction of thermal resistance has directly reduced LED brightness decay.Because of adopting brazing metal, do not have the adhesive of the low heat conductivity of epoxy resin, directly wafer is welded on the support, the thermal conductivity consistency between the different product is higher, thermal resistance is close, even so product use in the later stage in decay also can be consistent relatively.This scolder is difficult for oxidation after fusion, surperficial smoother, and fine the reflecting of light that can be better chip be produced, and irregular unlike the elargol class produce diffuse reflection, and the light diffuse reflection of chip production is eliminated.Therefore to a certain degree increasing than elargol product luminous flux.Scolder is a metal, does not exist in the long-time use of chip, as the problem of meeting glue flavescence blackening in elargol and the white glues series products, has eliminated a part of decay source on the basis, the life-span of having improved product.Adhesion obviously improves, and scolder has certain pliability, can effectively eliminate the different stress with the coefficient of expansion between the support of chip, reduces the product failure rate.Because of in solid brilliant process, with suction nozzle with chip pressure welding on the scolder that has fused, therefore can not produce as the flow displacement that causes wafer, inclination etc. of tin cream fusion bad; And do not have the scaling powder of increasing and so in the scolder, can not produce and pollute the abnormal quality that causes; Gu need not behind the crystalline substance to solidify baking, reduced production procedure, improved production efficiency.Material cost obviously reduces, and preservation condition is less demanding, and is easy to use.
Scolder has environment-friendly soldering and solder containing pb, and solder containing pb has and welds lubricant nature preferably, the product reliability height, use can be exempted on other semiconductor, and be used in the environmental requirement that do not reach of LED, therefore must adopt the environmental-friendly lead-free scolder, and lead-free solder is compared solder containing pb, easily dissolving at high temperature, it is relatively poor that welding contains lead welding.For guaranteeing the environmental protection characteristic of LED, must adopt lead-free solder, contain the multiple metal material of independent research in the lead-free solder, therefore having higher heat conductivity, reach more than the 50W/mk, is conventional more than 2-25 times of elargol that adopt, more than 25 times of white glues, the scolder that the present invention adopts, thermal conductivity reaches more than the 58w/mk, on parameter, adopt after this scheme, the heat that LED produces in time imports fin by scolder, thereby obviously reduces junction temperature of chip, thereby reduces LED brightness decay.For example, the present invention can adopt preferably and can be the low-temperature lead-free solder of SnSbAgNi.More preferably, the percentage composition of each component is: Sn 75-90%; Sb 5-15%; Ag 1-10%; Ni 0.1-5%.
Though adopt scolder to replace the solid brilliant heat-conducting glue of elargol or white glues operation great power LED to have lot of advantages, still have a lot of difficult point problems to solve:
The welding temperature problem: how the bearing temperature of LED framework guarantees welding reliability between the 260-320 degree, does not damage supporting structure simultaneously, with wafer admittedly well.
The thickness problem of scolder and adhesiveness problem: the thickness of scolder directly has influence on heat conduction, and the derivation of light also can have influence on electrically; The bad wafer that easily causes of adhesiveness comes off from support, easily causes LED to lose efficacy.
The problem in cavity: Gu behind the crystalline substance, if the empty excessive of the generation at the bottom of wafer easily causes heat conduction bad, and fragile chip.
The led chip problem: generally speaking, the white chip of LED is for forming as substrate crystalline substance of heap of stone with sapphire, and sapphire and solder bonds are relatively poor, thus must the back by evaporation on can with scolder mutually welding alloy.
Frame problem, what adopt because of the support of LED all be silver-plated support, and therefore silver products easily blackout jaundice in air generally all adds matcoveredn on the surface, and this protective layer plays inhibition to the fusing of scolder, needs solution.
For overcoming the above problems, solve by the following method:
The first step solves the welding temperature problem, adds the structure of plastic rubber material because of support adopts the copper post, and ratio of heat capacities is bigger, and the swollen rate that rises of plastic rubber material and copper product is different, therefore, needs the segmentation heating-up temperature.For example can be divided into 8 sections heating, 1 section-4 sections is the 150-240 degree, and 5 sections-7 sections is the 240-320 degree, and 8 sections is the 240-150 degree.
Second goes on foot the solution solder thickness and be stained with closing property affirmation problem with wafer: what of continuous adjustment scolding tin material the thickness of scolder pass through, and confirms whether thickness is suitable, at the adhesiveness problem, by the gas defendance, prevents its oxidation, the bonding force of increase support and chip.Need to confirm that by doing thrust test the instrument that thrust test need be bought specialty advances test with the bonding force of wafer,, confirm tin silk size and thrust size by continuous test.And inflated with nitrogen and hydrogen improve bonding force to play oxidation and the redox problem that prevents high temperature underframe and scolder.
The 3rd step solved empty problem, and the friction by when brilliant admittedly can reduce the cavity, and can detect the cavity size with X-ray machine.
The 4th step solved the core problem, cooperate with the production firm, by the mode at the bottom of wafer metal cladding, chip can well be joined with scolder, and thrust is obviously above elargol technology after the welding.
The 5th step solution framework problem is cleaned the support of buying back, removes the protective layer of rack surface, and melts soldering tin is better after cleaning by test, satisfies solid brilliant requirement.
Below, 1a to Fig. 1 c is described in detail operation of the present invention in conjunction with the accompanying drawings.
The first step in the middle of the copper post, is fused by certain temperature 1 in heat conduction scolder with it.Chip 2 is placed on the heat conduction scolder of fusion bondingly, after the cooling, die bonding is on scolder.
In second step, the chip both positive and negative polarity is connected by gold thread 3.
The 3rd step, use silica gel to add fluorescent material, with fluorescent material point on wafer.
The 4th step added angle protection lens, played control lighting angle and protection internal structure.
By adopting new solid crystalline medium, the heat that led chip produces is derived obviously, and by test, the lamp body surface temperature obviously reduces.
It should be noted that at last: above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement technical scheme of the present invention, and not break away from the spirit and scope of technical solution of the present invention.
Claims (8)
1. high-power LED encapsulation structure is characterized in that: have and adopt the solid brilliant structure of scolder, scolder is a lead-free solder.
2. encapsulating structure as claimed in claim 1 is characterized in that, scolder is SnSbAgNi.
3. encapsulating structure as claimed in claim 1 or 2 is characterized in that, when adopting scolder brilliant admittedly, adopts the segmentation heating.
4. encapsulating structure as claimed in claim 1 or 2 is characterized in that bottom of wafer is coated with metal level.
5. a high-power LED packaging method is characterized in that: comprise the steps: the heat conduction solder dots by certain temperature it to be fused in the middle of the metal of support; Chip is placed on the heat conduction scolder of fusion bondingly, after the cooling, die bonding is on scolder; Connect by the both positive and negative polarity of gold thread wafer; With fluorescent material point on wafer.
6. method for packing as claimed in claim 5 is characterized in that, heats by segmentation and fuses the heat conduction scolder.
7. method for packing as claimed in claim 5 is characterized in that, chip is placed on the heat conduction scolder of fusion when bonding, uses chip friction scolder, to reduce the cavity in the scolder.
8. method for packing as claimed in claim 5 is characterized in that, by the scolder fusion, obtains smooth surface.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201110196668 CN102255033B (en) | 2011-07-14 | 2011-07-14 | High-power LED (Light-Emitting Diode) encapsulating structure and encapsulating method |
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| CN 201110196668 CN102255033B (en) | 2011-07-14 | 2011-07-14 | High-power LED (Light-Emitting Diode) encapsulating structure and encapsulating method |
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| CN102255033A true CN102255033A (en) | 2011-11-23 |
| CN102255033B CN102255033B (en) | 2013-04-10 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106413285A (en) * | 2016-11-22 | 2017-02-15 | 株洲天微技术有限公司 | Microcircuit module back side pre-soldering and pre-soldering heating device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9938457B1 (en) | 2016-09-20 | 2018-04-10 | General Electric Company | Methods for fabricating devices containing red line emitting phosphors |
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| US20040124543A1 (en) * | 2002-12-30 | 2004-07-01 | Motorola Inc. | Low stress semiconductor die attach |
| CN1978122A (en) * | 2005-12-05 | 2007-06-13 | 株式会社日立制作所 | High-temperature solder, high-temperature solder paste and power semiconductor device using same |
| CN101369614A (en) * | 2007-08-17 | 2009-02-18 | 刘胜 | Packaging structure and method for high power white light LED |
| CN101661987A (en) * | 2009-09-15 | 2010-03-03 | 中山大学 | White light LED packaging structure and packaging method thereof |
| CN101740712A (en) * | 2009-12-17 | 2010-06-16 | 上海靖耕照明电器有限公司 | LED (Liquid Emitting Diode) crystal grain fixing method |
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2011
- 2011-07-14 CN CN 201110196668 patent/CN102255033B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040124543A1 (en) * | 2002-12-30 | 2004-07-01 | Motorola Inc. | Low stress semiconductor die attach |
| CN1978122A (en) * | 2005-12-05 | 2007-06-13 | 株式会社日立制作所 | High-temperature solder, high-temperature solder paste and power semiconductor device using same |
| CN101369614A (en) * | 2007-08-17 | 2009-02-18 | 刘胜 | Packaging structure and method for high power white light LED |
| CN101661987A (en) * | 2009-09-15 | 2010-03-03 | 中山大学 | White light LED packaging structure and packaging method thereof |
| CN101740712A (en) * | 2009-12-17 | 2010-06-16 | 上海靖耕照明电器有限公司 | LED (Liquid Emitting Diode) crystal grain fixing method |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106413285A (en) * | 2016-11-22 | 2017-02-15 | 株洲天微技术有限公司 | Microcircuit module back side pre-soldering and pre-soldering heating device |
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| CN102255033B (en) | 2013-04-10 |
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Address after: 528000 Guangdong Province, Foshan city Chancheng District ancient road No. 45 Patentee after: Foshan Blue Rocket Electronics Co., Ltd. Address before: 528000 Guangdong Province, Foshan city Chancheng District Road No. 1 Buddha Patentee before: Foshan Blue Rocket Electronics Co., Ltd. |