LED light source module and flip chip welding method

Abstract

The present invention provides an LED light source module and a flip-chip soldering method, wherein the LED light source module includes a substrate and at least one LED chip arranged on the substrate, the surface of the substrate is provided with a positive electrode soldering pad and a negative electrode soldering pad, the LED chip includes a positive electrode pin and a negative electrode pin, the positive electrode pin is soldered to the positive electrode soldering pad, and the negative electrode pin is soldered to the negative electrode soldering pad, and the spacing between the positive electrode soldering pad and the negative electrode soldering pad corresponding to a LED chip is greater than the spacing between the positive electrode pin and the negative electrode pin. In the LED light source module provided by the present invention, since the spacing between the positive electrode soldering pad and the negative electrode soldering pad corresponding to a LED chip is greater than the spacing between the positive electrode pin and the negative electrode pin, there is no need to adjust the spacing between the soldering pads of the substrate to be completely consistent with the spacing between the electrode pins of the LED chip, so that a conventional substrate structure can select a small-sized LED chip, reducing costs and reducing product volume.

Description

Technical Field

[0001] The present invention relates to the technical field of LED display, and in particular to an LED light source module and a flip-chip welding method. Background Art

[0002] Currently, LED light source modules typically consist of a substrate and LED chips. During fabrication, the LED chip is first transferred to the substrate's pads using the die bonder's suction nozzle. Once the nozzle is removed, the LED chip is soldered to the pads. To ensure accurate LED chip placement and avoid soldering defects such as open circuits, flying materials, and tilted soldering, and due to the limitations of the die bonder's suction accuracy, pads on the substrate must be positioned exactly in line with the LED chip's electrode pins.

[0003] However, for low-cost small-size LED chips, the spacing between their electrode pins is small, requiring the spacing between pads on the substrate to be reduced simultaneously. According to the current process level, it is difficult to set the pad spacing required by small-size LED chips on the substrate, resulting in the inability to use small-size LED chips in LED light source modules, resulting in higher costs and larger product sizes. Summary of the Invention

[0004] The primary purpose of the present invention is to provide an LED light source module that can optionally use small-sized LED chips.

[0005] Another object of the present invention is to provide a flip-chip soldering method suitable for preparing the above-mentioned LED light source module.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] As a first aspect, the present invention relates to an LED light source module, comprising a substrate and at least one LED chip arranged on the substrate, wherein a positive electrode pad and a negative electrode pad are provided on the surface of the substrate, and the LED chip comprises a positive electrode pin and a negative electrode pin, wherein the positive electrode pin is welded to the positive electrode pad, and the negative electrode pin is welded to the negative electrode pad, and the distance between the positive electrode pad and the negative electrode pad of a corresponding LED chip is greater than the distance between the positive electrode pin and the negative electrode pin.

[0008] Preferably, the LED chip is arranged at the midpoint of the line connecting the positive electrode pad and the negative electrode pad.

[0009] Preferably, the projection of the positive electrode pin on the plane where the positive electrode pad is located at least partially overlaps with the positive electrode pad, and the projection of the negative electrode pin on the plane where the negative electrode pad is located at least partially overlaps with the negative electrode pad.

[0010] Preferably, there are a plurality of LED chips, and the distance between two adjacent LED chips is the same.

[0011] Furthermore, the LED light source module also includes a packaging adhesive provided on the substrate and covering the LED chip.

[0012] As a second aspect, the present invention also relates to a flip-chip soldering method, which is suitable for preparing the above-mentioned LED light source module, and the flip-chip soldering method includes the following steps: applying solder on the soldering pad of the substrate; using a carrier to adsorb the LED chip above the soldering pad and contact it with the solder; fixing the carrier relative to the substrate; melting the solder by high-temperature heating to solder the LED chip to the soldering pad; and removing the carrier.

[0013] Preferably, a carrier is used to adsorb the LED chip onto the top of the soldering pad and bring it into contact with the solder, specifically comprising: providing a plurality of soldering pads; arranging a plurality of LED chips on the protective film in a one-to-one correspondence with the positions of the plurality of soldering pads; using a carrier to adsorb the plurality of LED chips at the same time; removing the protective film at the bottom of the LED chip; and transferring the plurality of LED chips simultaneously to the top of the plurality of soldering pads through the carrier and bringing them into contact with the solder.

[0014] Optionally, a carrier is used to adsorb the LED chip onto the top of the pad and bring it into contact with the solder, specifically comprising: providing a plurality of substrates, and arranging the plurality of LED chips on the protective film in a one-to-one correspondence according to the positions of the plurality of substrates; using a carrier to adsorb the plurality of LED chips at the same time; removing the protective film at the bottom of the LED chip; and transferring the plurality of LED chips simultaneously to the top of the pads of the plurality of substrates through the carrier and bringing them into contact with the solder.

[0015] Preferably, before using a carrier to adsorb the LED chip onto the top of the pad and bring it into contact with the solder, the method further comprises: configuring the carrier, and providing adhesive for bonding the LED chip on the bottom surface of the carrier.

[0016] Furthermore, after removing the carrier board, the method further includes: providing a packaging adhesive on the substrate to cover the LED chip.

[0017] Compared with the prior art, the solution of the present invention has the following advantages:

[0018] 1. In the LED light source module provided by the present invention, the distance between the positive electrode pad and the negative electrode pad corresponding to an LED chip is greater than the distance between the positive electrode pin and the negative electrode pin. There is no need to adjust the pad spacing of the substrate to be completely consistent with the electrode pin spacing of the LED chip, so that a conventional substrate structure can select a small-sized LED chip, reducing costs and reducing product volume.

[0019] 2. In the flip-chip soldering method provided by the present invention, the position of the LED chip can be limited and fixed by the carrier while the LED chip is transferred, so that the LED chip remains stationary during the heating and soldering process, thereby enabling small-sized LED chips to be stably soldered on a conventional substrate structure, significantly reducing product costs and improving production yield.

[0020] 3. In the flip-chip soldering method provided by the present invention, LED chips can be transferred and fixed in batches through the carrier board, so that the soldering process of multiple LED chips can be completed at the same time, effectively ensuring the installation accuracy of multiple LED chips, improving production efficiency, and reducing production cycle.

[0021] Additional aspects and advantages of the present invention will be set forth in part in the following description, will be obvious from the following description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0023] Figure 1 A schematic structural diagram of an LED light source module provided in an embodiment of the present invention;

[0024] Figure 2 A diagram showing the steps of the flip-chip soldering method provided by the present invention;

[0025] Figure 3 for Figure 2 The preparation flow chart for transferring LED chips in the flip chip bonding method shown;

[0026] Figure 4 for Figure 2 The preparation flow chart for soldering LED chips in the flip-chip soldering method shown. DETAILED DESCRIPTION

[0027] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0028] It will be understood by those skilled in the art that, unless otherwise stated, the term "comprising" as used in the description of the present invention refers to the presence of the features, integers, steps, operations, parts / components and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, parts / components, components and / or groups thereof. It should be understood that when we say a part / component is "connected" to another part / component, it can be directly connected to the other part / component, or there can be intermediate parts / components. The term "and / or" as used herein includes all or any one of the associated listed items and all combinations thereof.

[0029] like Figure 1 As shown, an embodiment of the present invention provides an LED light source module 1, including a substrate 11 and at least one LED chip 12 arranged on the substrate 11, the surface of the substrate 11 is provided with a soldering pad 111 for soldering the LED chip 12, and the LED chip 12 includes a pin 121 for transmitting a current signal, and the pin 121 is soldered to the soldering pad 111 through solder 13.

[0030] Preferably, the pad 111 includes a positive pad 1111 and a negative pad 1112, the pin 121 includes a positive pin 1211 and a negative pin 1212, the positive pin 1211 is welded to the positive pad 1111, the negative pin 1212 is welded to the negative pad 1112, and the spacing between the positive pad 1111 and the negative pad 1112 of a corresponding LED chip 12 is greater than the spacing between the positive pin 1211 and the negative pin 1212, that is, there is no need to adjust the pad spacing of the substrate 11 to be completely consistent with the electrode pin spacing of the LED chip 12, so that a conventional substrate structure can select a small-sized LED chip, reduce costs and reduce product volume.

[0031] Preferably, the LED chip 12 is arranged at the midpoint of the line connecting the positive electrode pad 1111 and the negative electrode pad 1112, so that the welding area of ​​the positive electrode pin 1211 relative to the positive electrode pad 1111 is equal to the welding area of ​​the negative electrode pin 1212 relative to the negative electrode pad 1112, thereby avoiding problems such as tilting or loosening of the LED chip 12 due to the different welding strengths of the positive electrode pin 1211 and the positive electrode pin 1211, and improving the installation strength of the LED chip 12.

[0032] More preferably, the projection of the positive pin 1211 on the plane where the positive pad 1111 is located at least partially overlaps with the positive pad 1111, and the projection of the negative pin 1212 on the plane where the negative pad 1112 is located at least partially overlaps with the negative pad 1112, so as to ensure that both the positive pin 1211 and the negative pin 1212 have at least part of their structure supported directly above the pad 111, thereby ensuring the stability of the LED chip 12.

[0033] Furthermore, the LED light source module 1 also includes a packaging glue 14 provided on the surface of the substrate 11 and covering the LED chip 12. The packaging glue 14 can be made of silicone material to have a high refractive index and high transmittance, thereby increasing the luminous flux of the LED chip 12. Moreover, due to its low viscosity and easy degassing, it is suitable for potting and molding, so that the LED light source module 1 has good durability and reliability.

[0034] In other embodiments, there may be multiple LED chips 12, and the multiple LED chips 12 are arranged on the substrate 11, and the distance between two adjacent LED chips 12 is the same, thereby improving the brightness of the LED light source module 1 and ensuring overall uniform light output.

[0035] like Figure 2 As shown, as a second aspect, an embodiment of the present invention further provides a flip-chip soldering method suitable for preparing the above-mentioned LED light source module 1, and the flip-chip soldering method comprises the following steps:

[0036] Step S1 : applying solder 13 on the pad 111 of the substrate 11 .

[0037] Solder pads 111 are pre-arranged on the substrate 11 based on the number and position requirements of the LED chips 12. The LED chips 12 include positive pins 1211 and negative pins 1212. The solder pads 111 include positive solder pads 1111 and negative solder pads 1112, which are arranged in a one-to-one correspondence with the positive pins 1211 and negative pins 1212. When arranging the solder pads 111, the spacing between the positive solder pads 1111 and the negative solder pads 1112 corresponding to each LED chip 12 is greater than the spacing between the positive pins 1211 and the negative pins 1212. This eliminates the need to adjust the solder pad spacing of the substrate 11 to be completely consistent with the spacing between the electrode pins of the LED chips 12. Furthermore, there is no need to use more precise equipment to form the solder pads 111 on the substrate 11. This allows the conventional substrate structure to use small-sized LED chips, reducing costs and product size.

[0038] Furthermore, before applying the solder 13 , the pad 111 should be cleaned first to avoid defects or contamination on the surface of the pad 111 that may cause the tensile strength and bonding strength uniformity of the pad 111 to deteriorate, thereby ensuring the conductivity and reliability of the pad 111 .

[0039] Specifically, the solder 13 is tin paste, which is applied to the top surface of the pad 111 and forms a bump structure with a high middle and low surroundings under the action of the tension of the solder 13 itself, so that the solder 13 can fix itself on the pad 111 and is not easy to flow out of the pad 111, thereby ensuring insulation between two adjacent pads 111.

[0040] Step S2 : using the carrier board 2 to adsorb the LED chip 12 onto the solder pad 111 and contact it with the solder 13 .

[0041] First, configure the carrier 2, and set an adhesive 21 on the bottom surface of the carrier 2 for bonding the LED chip 12. The adhesive force of the adhesive 21 on the LED chip 12 should be greater than the gravity of the LED chip 12, so that the carrier 2 meets the requirements of adsorbing and transferring the LED chip 12.

[0042] Preferably, the adhesive 21 is a UV photolytic adhesive 1, which is prepared by adding an appropriate amount of plasticizer, tackifying resin, and photosensitive resin to a viscous monomer with a low glass transition temperature. It has the properties of a pressure-sensitive adhesive under normal conditions and can quickly fail after ultraviolet exposure, so as to separate the LED chip 12 from the carrier board 2.

[0043] Please combine Figure 3 When there are multiple solder pads 111 on the substrate 11, the multiple LED chips 12 are first arranged on the protective film 3 in a one-to-one correspondence according to the positions of the multiple solder pads 111. Then, the carrier 2 is moved directly above the multiple LED chips 12, and downward pressure is applied to the carrier 12 to fully bond the adhesive 21 to the LED chips 12. The multiple LED chips 12 are then simultaneously adsorbed by the adhesive 21 on the carrier 2. Finally, the protective film 3 on the bottom of the LED chips 12 is removed. At this point, the multiple LED chips 12 are arranged on the carrier 2 according to the positions of the multiple solder pads 111. The carrier 2 can be used to simultaneously transfer the multiple LED chips 12 to the top of the solder pads 111 and contact the solder 13, realizing batch transfer of chips. This allows the soldering process of the multiple LED chips 12 to be completed simultaneously, effectively ensuring the installation accuracy of the multiple LED chips 12, improving production efficiency, and reducing production cycle time.

[0044] In another embodiment, the substrate 11 may also be provided with multiple substrates 11, and the multiple substrates 11 are arranged according to preset positions. The multiple LED chips 12 are first arranged on the protective film 3 according to the positions of the multiple substrates 11 in a one-to-one correspondence. The multiple LED chips 12 can also be synchronously transferred to the multiple substrates 11 through the carrier 2, thereby realizing the simultaneous generation and manufacturing of multiple LED light source modules 1.

[0045] Specifically, the carrier board 2 is used to adsorb the LED chip 12 onto the top of the soldering pad 111 so that the LED chip 12 is in contact with the solder 13. At the same time, a certain distance should be maintained between the LED chip 12 and the soldering pad 111, thereby leaving a space for accommodating the solder 13 between the pin 121 of the LED chip 12 and the soldering pad 111, ensuring that the solder 13 can be fully soldered and avoiding the pin 121 and the soldering pad 111 from pressing against each other and squeezing the solder 13 out of the soldering pad 111.

[0046] Step S3: Fix the carrier plate 2 relative to the substrate 11 .

[0047] Please combine Figure 4 After the carrier board 2 and the LED chip 12 on the carrier board 2 are synchronously moved to the top of the substrate 1, the carrier board 2 can be fixed by mechanical equipment or related limiting structures so that the carrier board 2 is fixed relative to the substrate 11.

[0048] Specifically, the carrier board 2 limits and fixes the LED chip 12, so that the LED chip 12 can be fixed relative to the substrate 11, so that the LED chip 12 can remain fixed during the subsequent welding process, avoiding the installation position of the LED chip 12 from shifting, and there is no need to adjust the pad spacing of the substrate 11 to be completely consistent with the electrode pin spacing of the LED chip 12, so that small-sized LED chips can be stably welded on a conventional substrate structure, greatly reducing product costs and improving production yield.

[0049] Step S4 : melting the solder 13 by high-temperature heating to solder the LED chip 12 to the solder pad 111 .

[0050] exist Figure 4 As shown in the figure, after the carrier 2 is fixed relative to the substrate 11, the solder 13 is heated at a high temperature to melt the solder 13, and the fluidity and tension of the melted solder 13 are used to wrap the pins 121 of the LED chip 12 and the pad 111 to form a welding structure, thereby welding the LED chip 12 to the pad 111.

[0051] Preferably, a reflow soldering machine with uniform and stable temperature and accurate control is selected to perform reflow soldering on the LED chip 12 to ensure soldering quality, improve the bonding integrity of the LED chip 12 relative to the solder pad 111, and prevent thermal shock from damaging the LED chip 12.

[0052] It is worth noting that during the heating of the solder 13, the relative positions of the carrier 2 and the substrate 11 should be kept unchanged, and the adhesive 21 should be prepared by reasonably controlling the heating position and selecting suitable materials to ensure that the adhesive 21 on the carrier 2 will not be affected by high temperature and fail, thereby ensuring that the LED chip 12 will not move during the heating process, thereby achieving the purpose of accurately controlling the installation position of the LED chip 12.

[0053] Step S5: remove the carrier board 2.

[0054] After the LED chip 12 is soldered to the solder pad 111 and the soldered structure is cooled, the adhesive 21 is subjected to an invalidation treatment, and finally the carrier board 2 is removed.

[0055] When removing the carrier board 2, avoid moving or colliding with the LED chip 12 to ensure that the LED chip 12 remains in the same position. Furthermore, the adhesive 21 must be completely cleaned from the surface of the LED chip 12 to prevent any residual adhesive 21 from remaining on the surface of the LED chip 12, thereby ensuring the lifespan and light output of the LED chip 12.

[0056] Furthermore, after removing the carrier board 2, a packaging glue 14 covering the LED chip 12 is provided on the surface of the substrate 11. The packaging glue 14 can be made of liquid silicone rubber made of silicone as the main raw material, so as to have good high and low temperature resistance and electrical insulation ability, and have excellent dielectric capacity and moisture resistance, as well as good refractive index and transmittance.

[0057] Finally, the preparation process of the LED light source module 1 is completed. Since the flip-chip welding method has high welding precision and high production efficiency, the yield rate of the LED light source module 1 can be greatly improved and the production cycle can be shortened, so that the use of small-size LED chips can be realized, the production cost can be reduced, the product volume can be reduced, and the product competitiveness can be improved.

[0058] The above descriptions are only partial embodiments of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A flip chip soldering method, characterized in that: The flip chip welding method comprises the following steps: S1: applying solder to the pads of the substrate, and arranging the pads on the substrate according to the number and position requirements of the LED chips, wherein the LED chips include positive pins and negative pins, and the pads include positive pads and negative pads that are arranged in a one-to-one correspondence with the positive pins and the negative pins, and the pads are arranged so that the spacing between the positive pad and the negative pad corresponding to one LED chip is greater than the spacing between the positive pin and the negative pin; S2: Using a carrier board to adsorb the LED chip onto the pad and contact it with the solder, specifically including: There are multiple pads; Arrange the plurality of LED chips on the protective film in a one-to-one correspondence with the positions of the plurality of solder pads; Adopting a carrier plate to simultaneously absorb the plurality of LED chips; Removing the protective film at the bottom of the LED chip; Transferring the plurality of LED chips simultaneously to the top of the plurality of solder pads via the carrier and contacting the LED chips with the solder; Or, specifically including: There are multiple substrates, and the multiple substrates are arranged according to preset positions; Arrange the plurality of LED chips on the protective film in a one-to-one correspondence with the positions of the plurality of substrates; Adopting a carrier plate to simultaneously absorb the plurality of LED chips; Removing the protective film at the bottom of the LED chip; Transferring the plurality of LED chips simultaneously to the solder pads of the plurality of substrates through the carrier and contacting the LED chips with the solder; S3: fixing the carrier plate relative to the substrate; S4: melting the solder by high-temperature heating to solder the LED chip to the solder pad; S5: removing the carrier board.

2. The flip chip bonding method according to claim 1, wherein: The LED chip is arranged at the midpoint of a line connecting the positive electrode pad and the negative electrode pad.

3. The flip chip bonding method according to claim 1, wherein: The projection of the positive electrode pin on the plane where the positive electrode pad is located at least partially overlaps with the positive electrode pad, and the projection of the negative electrode pin on the plane where the negative electrode pad is located at least partially overlaps with the negative electrode pad.

4. The flip chip bonding method according to claim 1, wherein: There are multiple LED chips, and the distance between two adjacent LED chips is the same.

5. The flip chip bonding method according to claim 1, wherein: It also includes a packaging glue arranged on the substrate and covering the LED chip.

6. The flip chip bonding method according to claim 1, wherein: Before using the carrier board to adsorb the LED chip onto the solder pad and contact it with the solder, the method further includes: A carrier board is provided, and adhesive for bonding the LED chip is provided on the bottom surface of the carrier board.

7. The flip chip bonding method according to claim 1, wherein: After removing the carrier board, the method further comprises: A packaging adhesive covering the LED chip is provided on the substrate.

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