Failure prediction device and circuit board using the same

Patent metadata

Field	Value
Publication number	US-10837997-B2
Application number	US-201716346164-A
Country	US
Kind code	B2
Filing date	Oct 20, 2017
Priority date	Dec 20, 2016
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

A failure prediction device is provided for predicting, using a structure having a high degree of design freedom, failure at a soldered joint due to vibration stress, and a circuit board using the same. The failure prediction device is disposed on a substrate having a mounting component that is fixed thereon through a solder joint. The failure prediction device is provided with a load amplifying portion that includes a pair of support leg portions each having one end to be fixed to the substrate or the mounting component, and a sacrificial fracture portion that is supported by the other ends of the pair of support leg portions, wherein the load amplifying portion transmits, to the sacrificial fracture portion via the pair of support leg portions, vibration that is applied to the substrate.

First claim

The invention claimed is:

1. A failure prediction device provided on a substrate having a mounting component that is fixed through a solder joint, comprising:
a load amplifying portion including a pair of support leg portions each having a first end fixed to the substrate or the mounting component, and a second end, and
a first sacrificial fracture portion supported by the respective second ends of the pair of support leg portions,
wherein the load amplifying portion transmits, to the first sacrificial fracture portion via the pair of support leg portions, vibration applied to the substrate.

2. The failure prediction device according to claim 1 , further comprising a measurement section to measure an electrical characteristic of the load amplifying portion, wherein failure caused by a crack or fracture of the solder joint is predicted based on a measurement result of the measurement section.

3. The failure prediction device according to claim 1 , wherein the first sacrificial fracture portion is disposed apart from the substrate or the mounting component in an out-of-plane direction of the substrate.

4. The failure prediction device according to claim 1 , wherein the first sacrificial fracture portion is made of a material different from that of the pair of support leg portions and has lower fracture strength than the pair of support leg portions.

5. The failure prediction device according to claim 1 , wherein a sectional area of the first sacrificial fracture portion is formed smaller than a sectional area of the pair of support leg portions.

6. The failure prediction device according to claim 1 , wherein the first sacrificial fracture portion is provided with a notch.

7. The failure prediction device according to claim 1 , wherein natural frequency of the load amplifying portion is matched to a frequency of vibration stress applied to the substrate.

8. The failure prediction device according to claim 1 , wherein a mounting weight is placed on the first sacrificial fracture portion.

9. The failure prediction device according to claim 1 , wherein each of the pair of support leg portions has a leg having one end to be fixed to the substrate or the mounting component, and a bridge connection portion connecting the leg and the first sacrificial fracture portion, and a bridge portion is structured in which the bridge connection portion is provided to both ends of the first sacrificial fracture portion.

10. The failure prediction device according to claim 9 , wherein the bridge connection portions are formed of an elastic material, and the first sacrificial fracture portion is elastically sandwiched by the bridge connection portions.

11. The failure prediction device according to claim 9 , wherein the load amplifying portion further comprises a second sacrificial fracture portion disposed at a connecting portion between the leg and the bridge connection portion of each of the pair of support leg portions.

12. The failure prediction device according to claim 9 , wherein the load amplifying portion comprises the bridge portion including multiple bridge portions arranged in a plane parallel to the substrate.

13. The failure prediction device according to claim 1 , wherein the load amplifying portion comprises the first sacrificial fracture portion including multiple sacrificial fracture portions arranged in an out-of-plane direction of the substrate.

14. The failure prediction device according to claim 13 , wherein a major factor of failure is determined among vibration stress and thermal stress based on arrangement positions in the out-of-plane direction of the first sacrificial fracture portions that are fractured among the multiple first sacrificial fracture portions, and on a number of the first sacrificial fracture portions that are fractured.

15. A circuit board comprising the failure prediction device according to claim 1 and the substrate on which the failure prediction device is disposed.

16. The failure prediction device according to claim 1 , further comprising a measurement section to measure an electrical characteristic of the load amplifying portion, wherein, based on a measurement result of the measurement section, failure caused by a crack or fracture of the solder joint is predicted, and
the first sacrificial fracture portion is disposed apart from the substrate or the mounting component in an out-of-plane direction of the substrate.

17. The failure prediction device according to claim 2 , wherein the first sacrificial fracture portion is made of a material different from that of the pair of support leg portions and has a lower fracture strength than the pair of support leg portions.

18. The failure prediction device according to claim 3 , wherein the first sacrificial fracture portion is made of a material different from that of the pair of support leg portions and has a lower fracture strength than the pair of support leg portions.

19. The failure prediction device according to claim 16 , wherein the first sacrificial fracture portion is made of a material different from that of the pair of support leg portions and has a lower fracture strength than the pair of support leg portions.

Assignees

• Mitsubishi Electric Corp

Inventors

• Ando Nobuaki
• Sakamoto Hiroo
• Echizenya Daisuke

Classifications

• G01R31/2812

  Checking for open circuits or shorts, e.g. solder bridges; Testing conductivity, resistivity or impedance (of connections G01R31/66) · CPC title

• H05K1/181

  associated with surface mounted components · CPC title

• G01R31/2817 Primary

  Environmental-, stress-, or burn-in tests (of IC's G01R31/2855; of individual semiconductors G01R31/2642; of other circuits G01R31/2849) · CPC title

• H05K2203/308

  Sacrificial means, e.g. for temporarily filling a space for making a via or a cavity or for making rigid-flexible PCBs · CPC title

• G06F30/23

  using finite element methods [FEM] or finite difference methods [FDM] · CPC title