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Electronic assembly welding spot for temperature circulation

An electronic component and temperature cycle technology, applied in the direction of electrical components, electrical solid devices, circuits, etc., can solve the problems of increasing the cost of electronic components, long filling process, and increasing manufacturing time, so as to reduce the occurrence probability of solder joint fracture and relieve Stress, the effect that is conducive to miniaturization

Active Publication Date: 2019-10-25
CHINA-SINGAPORE INT JOINT RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method has the following defects: First, due to the filling of thermosetting polymers, it is difficult to partially replace a component in the circuit board assembly when a defect occurs, and the entire circuit board assembly needs to be discarded
Second, the method increases the cost of the electronic assembly since the filled polymer is rather expensive
Third, since the filling of thermosetting polymers is achieved by capillary action, the filling process will be very long, increasing manufacturing time and reducing production efficiency
However, this design transfers failure from the solder joint to the polyimide-copper pad interface, which is even weaker than the solder-copper pad interface

Method used

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  • Electronic assembly welding spot for temperature circulation
  • Electronic assembly welding spot for temperature circulation
  • Electronic assembly welding spot for temperature circulation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] Such as figure 2 As shown, consider the electronic assembly as a three-layer assembly where the solder joints are sandwiched between substrates #1 and #2. The current practice is to fill the interlayer with solder joints of the same size and shape at equal axis distances. When the component experiences a temperature excursion ΔT, the distribution of the shear stress experienced by the solder joint is approximated by the formula where ε T is the differential thermal strain between the two substrates, l is the distance from the centerline to the edge of the electronic component, and x is the distance from the centerline; lambda x and κ s are the planar tensile compliance and shear compliance of the component, respectively, the formula The accuracy has been verified by finite element analysis method. An electronic component is a two-dimensional structure, although What is described is only the distribution of shear stress in the x direction, but the distributio...

Embodiment 2

[0057] In this embodiment, based on optimizing the shear flexibility of the solder joints, the technical idea of ​​making the solder joints from the center line to the edge of the electronic component have a more even distribution of shear force and moment. In this embodiment, the equivalent shear area of ​​the solder joints is designed to be non-uniformly distributed from the center line to the edge of the electronic component - from large to small (such as Figure 7 shown). Equivalent shear area A of solder joint 3s , and the distribution in the x direction is: Among them, A 3o is the representative shear area at x=l.

[0058] At this point the shear compliance of the solder joint will be where κ o = h 3 p x p y / (G 3 A 3o ),G 3 is the shear modulus of the solder joint. At the same time, it is necessary to maintain the nodal area p x p y does not vary with x, so the shear force on the solder joint will be and the end moment will be M joint ≈F joint h 3 / ...

Embodiment 3

[0062] In this embodiment, based on optimizing the shear flexibility of the solder joints, the technical idea is to make the solder joints of the electronic component have a more even shear force and moment distribution from the center line to the edge. This embodiment designs the wheelbase area (being p x p y ) from the center line to the edge of the electronic component for non-uniform distribution – from dense to sparse (such as Figure 8 shown). Its distribution in the x direction is: where A po is the wheelbase area at x=l. At the same time, it is necessary to maintain the representative shear area of ​​the solder joint (A 3s ) does not vary with x. Thus, the shear force on the solder joint will be and the end moment will be M joint ≈F joint h 3 / 2. Both do not vary with the x direction, such as Figure 8 shown.

[0063] The foregoing embodiments describe the mathematically optimal distribution of the axle-base area of ​​solder joints along the x-direction ...

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Abstract

The invention discloses an electronic assembly welding spot for temperature circulation. The welding spot is also called an interconnection point and is used for packaging an electronic assembly, wherein the axle distance or the section area of the cross section of the interconnection point is distributed in a non-uniform manner from the center line of the electronic assembly to the edge of the electronic assembly. The cross section of the interconnection point is in the shape of an irregular polygon, and the axle distance of the interconnection point is distributed in a non-uniform manner from dense to sparse from the center line of the electronic assembly to the edge of the electronic assembly. The cross-sectional area of the interconnection point is distributed in a non-uniform manner from large to small from the center line of the electronic assembly to the edge of the electronic assembly. The interconnection point is in the shape of a sand clock. The electronic assembly welding spot has the characteristic of different spot size or non-uniform distribution of the welding spot, provides the optimal distribution of the welding spot sizes and axle distances and also provides the optimal welding spot shape at the same time, thereby enabling each welding spot and each part of the welding spot to bear the equal stress, relieving the stress borne by the tail end of the corner welding spot, and reducing the occurrence probability of welding spot breakage.

Description

technical field [0001] The invention relates to the technical field of semiconductor packaging, in particular to a solder joint of an electronic component used to withstand temperature cycles. Background technique [0002] Semiconductor packaging is an important link in the semiconductor device value chain. The key to semiconductor packaging lies in the electrical, thermal and mechanical interconnections between chips and chips, chips and packages, packages and packages, and packages and boards. Solder joints are the most common method for interconnecting semiconductor packages because of their ease of manufacture and stable performance in reliability testing. [0003] An electronic assembly can be viewed as a three-layer assembly where solder joints are sandwiched between two substrates with different physical, mechanical and geometric properties. Temperature cycling is one of the most challenging reliability testing conditions. Due to the alternating differential therma...

Claims

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Application Information

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IPC IPC(8): H01L23/488
CPCH01L23/488
Inventor 王毅华沈乔飞
Owner CHINA-SINGAPORE INT JOINT RES INST
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