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A kind of preparation method of BGA nano particle reinforced solder ball

A technology of nano-particles and solder balls, applied in welding equipment, welding media, manufacturing tools, etc., can solve the problems of high cost, high heating temperature, and no good solution for small batches of required diameter solder balls, etc., and achieve low cost , the effect of convenient method

Inactive Publication Date: 2018-02-02
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] At present, the preparation process of traditional lead-free solder balls includes wire cutting and melting process, spray forming process and swing forming process, etc. The cost is high, and the equipment consumes a lot of materials. It requires at least 10Kg of powder or block raw materials, which is only suitable for large batches of solder balls. preparation, and the heating temperature is high, the environmental purification requirements are high, and the process flow is complicated
At present, there is no example of adding nanoparticle BGA solder balls, and there is no good solution for small batch requirements and the preparation of solder balls with various diameters.

Method used

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  • A kind of preparation method of BGA nano particle reinforced solder ball
  • A kind of preparation method of BGA nano particle reinforced solder ball
  • A kind of preparation method of BGA nano particle reinforced solder ball

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] A preparation of BGA reinforced solder balls with nanoparticles (POSS particles), base material SAC305 lead-free eutectic powder, adding 3% POSS nanoparticles, mechanical stirring and mixing for half an hour, and then mixing with 60 rpm The powder was high-energy ball milled for 10 hours to obtain a certain physical combination.

[0029] Mix the composite powder and rosin-type solder paste at a ratio of 88:12, stir mechanically for half an hour, mix well, and store in the refrigerator. Then use the next image 3 A circular hole steel mesh with a diameter of 0.48mm and a thickness of 0.1mm, apply a small amount of compound solder paste, use a scraper to brush it on a glass plate through a mesh of a specific area, and then put it into a heating plate with a temperature of 240°C Put it on, keep it warm for 15s, then take it off to cool, scrape it off with tweezers and put it into a small box, the balls are formed. Put the prepared POSS-strengthened pellets into a beaker ...

Embodiment 2

[0036] The addition effect of nanoparticles was analyzed by EDS energy spectrum, and the microscopic morphology of solder joints was further observed by SEM.

[0037] The prepared POSS strengthened solder balls are heated and planted on the chip, and further reflow soldered to obtain a complete BGA device in which the PCB and the chip are packaged together. Grind and polish the solder joints on one side of the complete device to observe the effect of the solder joints, and further test the weldability and reliability of POSS strengthened solder balls.

[0038] The main elements of POSS nanoparticles are Si and O elements, figure 2 In , the EDS element surface scanning is performed on the solder joints, and it can be observed that the Si and O elements are evenly distributed, and the POSS particles are evenly distributed, and a good addition effect is obtained.

[0039] In order to observe the good connection effect and weldability, SEM microscopic morphology observation was ...

Embodiment 3

[0041] The BGA solder ball developed by the present invention is prepared by mesh printing with composite solder paste. Since the effect of adding nanoparticles in the composite solder paste directly determines the effect of adding nanoparticles in BGA solder joints, it is therefore used in lapped Cu Apply a small amount of solder paste on the chip to prepare simulated solder joints, and conduct electron microscope observation at 2000 times. Figure 4 Among them, (a) is the SAC305 solder joint without adding, (b) is the composite solder joint with 3% POSS added, and (c) is the composite solder joint with 0.05% CNTs added. It can be seen that the microstructure is refined, And the effect of adding nanoparticles is good.

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Abstract

The invention discloses a preparation method of nanoparticle reinforcing solder balls for a BGA, and belongs to the technical field of welding materials. The method includes the following steps of mechanically stirring, mixing and grinding SAC305 eutectic powder and nanoparticles in proportion to obtain composite powder, mixing the composite powder with rosin type flux paste in certain proportion, making paste pass through meshes of a silk screen or a printing steel net through a scraper to be printed on a glass panel, putting the glass panel printed with a certain volume of paste into a vacuum heat preserving box or onto a heating plate so that balls can be prepared through melting, and conducting forming, scraping, cleaning, drying and screening. The screened solder balls are selected appropriately for BGA welding reballing.

Description

technical field [0001] The invention relates to a method for preparing solder balls strengthened by nanoparticles for BGA, which belongs to the technical field of soldering materials, in particular electronic packaging materials. Background technique [0002] At present, most of the BGA packages use SAC305 lead-free solder balls, which have relatively the best solderability among lead-free solders, but their fatigue resistance is poor. The current lead-free eutectic alloys also need to improve their performance to meet the increasing requirements of electronic packaging. There are two development trends of lead-free solder that have attracted the attention of the industry. One is the multi-component alloying of lead-free solder, that is, the existing Based on lead-free solders such as Sn-based or Sn-Ag-based, multi-component alloy elements are added to improve the performance of the solder by adding components; the other direction is composite lead-free solder, mainly based ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23K35/40
CPCB23K35/40
Inventor 汉晶谷朋浩郭福
Owner BEIJING UNIV OF TECH