CN103219251B - A kind of method using metal-based nano fiber composite heat sink material to encapsulate large size chip - Google Patents

Abstract

The present invention mainly discloses and a kind ofly can substitute the packaging technology that thermal grease conduction and heat-conducting cream are applied to the nanoscale interface heat sink material on large size chip, the metal-based nano fibrous composite that to be exactly specifically that prepared by electrospinning and high stamping technology is as interface heat sink material, carry out reflow solder technique and fix large size chip on tellite, thus make chip have better heat dispersion.

Description

A kind of method using metal-based nano fiber composite heat sink material to encapsulate large size chip

Technical field

The present invention is mainly concerned with and a kind ofly can substitutes the packaging technology that thermal grease conduction and heat-conducting cream are applied to the nanoscale interface heat sink material on large size chip, be exactly specifically that interface heat sink material made by that metal-based nano fibrous composite prepared by electrospinning and high stamping technology, carry out reflow solder technique and fix large size chip on tellite, thus make chip have better heat dispersion.

Background technology

Interface heat sink material is the quite extensive and very important material of a class application, is mainly used in filling up the space between bi-material contact-making surface, forms a kind of sandwich structure and effectively reduce contact heat resistance, reduce thermal impedance between contact-making surface.Along with the appearance of very lagre scale integrated circuit (VLSIC) and high-density packages, electronic devices and components caloric value is more and more higher, and more and more higher to the requirement of heat radiation, interface heat sink material also seems all the more important, and its role is also more and more crucial.

In current microelectronics Packaging field, in order to improve by chip to heat sink heat radiation, extensive use various interfaces heat sink materials, comprising thermally conductive grease, heat-conducting glue, cooling pad, Heat dissipation adhesive tape, phase-change material and heat-conducting cream etc.But these materials often can not reach the urgent cooling requirements of large scale high power density chip.So also have some interface heat sink materials to be that metal material or carbon nano-tube material by adding high thermal conductivity in the basis materials such as polymer carries out raising heat conductivility.But, such composite material often can not be so soft or have mobility as thermal grease conduction, heat-conducting cream, result in and often occur a lot of problem being applied in large size chip technique, such as porosity raises and the thermal coefficient of expansion of chip does not mate generation interface slight crack etc., all cause the rising of interface resistance, be unfavorable for the heat radiation of high power density chip on the contrary.This patent is by carrying out surface treatment to large size chip adhesive surface, and splash-proofing sputtering metal layer, and the reflow solder technique by optimizing, can be bonded to substrate the metal-based nano fiber composite thin slice of different-thickness, and have efficient heat transfer efficiency.

Summary of the invention

The object of this invention is to provide the interface heat sink material technology on the extensive use of a kind of energy and oversize chip, reach lower voidage, the bonding techniques of unbounded facial cleft trace, thus the heat that very lagre scale integrated circuit (VLSIC) produces efficiently is shed.

The object of the invention is to be achieved through the following technical solutions.

A kind of method using metal-based nano fiber composite heat sink material to encapsulate large size chip of the present invention, is characterized in that method has following technical process and step:

A. polyimides PI and dimethylacetylamide are carried out with 1:5 proportioning wiring solution-forming, under high pressure 18KV, carry out electrospinning processes form nanometer fiber net, and then carry out high pressure the indium metal under molten condition is rushed in nanofiber grid, form metal-based nano fiber interface heat sink material;

B. the chip cutting into certain size is put into acetone soln, carry out ultrasonic cleaning 3 minutes, then use deionized water clearly ultrasonic

Wash 3 minutes;

C. chip is put into dry etching machine, etching 1-2 minute is carried out to chip back;

D. then chip is put into magnetron sputtering instrument chamber, the Ti that thickness is 20nm is first sputtered to chips in etching face, then sputters the Au of 100nm;

E. prefluxing Tacflux012 is on chip back and substrate pads respectively, and pad is that nickel plating Dip gold process makes herein;

F. then above-mentioned metal-based nano fiber heat sink material thin slice is clipped in the middle of chip and tellite, uniform pressurization;

G. sample is put in reflow ovens, carries out reflow soldering, and counterflow condition sets: maximum temperature: 180 degrees Celsius, return time 180s.

Accompanying drawing explanation

Fig. 1 is the structural representation of packaged sample of the present invention.

Fig. 2 is that the X-RAY that the present invention completes the sample after encapsulation detects picture.

Fig. 3 is the sample heat conductivility test result after the present invention completes encapsulation.

Embodiment

Describe the present invention below in conjunction with embodiment.

embodiment 1

Packaging technology step in the present embodiment is as follows:

1. polyimides PI and dimethylacetylamide are carried out with 1:5 proportioning wiring solution-forming, under high pressure 18KV, carry out electrospinning processes form nanometer fiber net, and then carry out high pressure the indium metal under molten condition is rushed in nanofiber grid, form metal-based nano fiber interface heat sink material.

2. the chip cutting into 30cm*30cm is put into acetone soln, carry out ultrasonic cleaning 3 minutes, then use deionized water ultrasonic cleaning 3 minutes.

3. chip is put into dry etching machine, etching is carried out 2 minutes to chip back, pollution-free to reach chip surface.

4. then chip is put into magnetron sputtering instrument chamber, the Ti that thickness is 20nm is first sputtered to chips in etching face, then the Au. Ti sputtering 100nm is good transition zone between semiconductor and metal, thus the metal of follow-up sputtering is not peeled off.

5. prefluxing Tacflux012 is on chip back and substrate pads respectively to utilize manual screen printing technology, and pad is that nickel plating Dip gold (ENIG:Electroless Nickel and Immersion Gold) makes herein.

6. then nanoscale interface heat sink material thin slice is clipped in the middle of chip and substrate, uniform pressurization 1-5psi.

7. sample is put in reflow ovens, carries out reflow soldering, counterflow condition sets: maximum temperature: 180 degrees Celsius, and after return time 180s. refluxes, simply clean sample with ethanol, the flux cleaning making it unnecessary is fallen.

Instrument detects and test uses X-RAY detector and T3Ster Thermal test system to carry out observation and analysis.Fig. 2 shows different size chip package rear interface situation, after can finding out large size chip encapsulation, large cavity does not occur.Fig. 3 shows the heat conduction situation after different size chip package, and the capacity of heat transmission after large size chip encapsulation is very good, can not occur large crackle by indirect proof interface heat dissipation channel, and encapsulation is good.This totally proves that this nanoscale interface heat sink material successful Application is dispelled the heat on large size chip.Fig. 1 is the structural representation of packaged sample of the present invention.

Claims (1)

1. the method using metal-based nano fiber composite heat sink material to encapsulate large size chip is characterized in that having following process and step:

A. polyimides (PI) is carried out 1:5 proportioning with dimethylacetylamide (Dimethylacetamide) and become solution, under high pressure 18KV, carry out electrospinning processes form nanometer fiber net, and then carry out high pressure the indium metal under molten condition is rushed in nanofiber grid, form metal-based nano fiber interface heat sink material.

B. the chip cutting into different size is put into acetone soln, carry out ultrasonic cleaning 3 minutes, then use deionized water ultrasonic cleaning 3 minutes.

C. chip is put into dry etching machine, etching is carried out 2 minutes to chip back.

D. then chip is put into magnetron sputtering instrument chamber, the Ti that thickness is 20nm is first sputtered to chips in etching face, then sputters the Au. of 100nm

E. prefluxing Tacflux012 is on chip back and substrate pads respectively, and pad is that nickel plating Dip gold (ENIG:Electroless Nickel and Immersion Gold) makes herein.

F. then nanoscale interface heat sink material thin slice is clipped in the middle of chip and substrate, uniform pressurization.

G. sample is put in reflow ovens, carries out reflow soldering, and counterflow condition sets: maximum temperature: 180 degrees Celsius, return time 180s.