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Semiconductor Defect Analysis

The observation images of the pre-mounted package are used to identify changes in the package after circuit board mounting, to conduct surface polishing and cross-section polishing of the defective area, and to identify the causes. If there are several defects of the same mode, the analysis and observation can be conducted for both surface polishing and cross-section polishing.
< Analysis results and judgment >
A void has occurred in the changed area, so after a solder ball connects the electronic component to the circuit board, an underfill was injected to strengthen the bond. A “gap” is thought to have occurred in the while area.
超音波探傷装置によるPKG内部密着度観察
超音波装置によるPKG内部密着度観察
断面研磨方向
Circuit board cross-section polishing

Circuit board cross-section polishing

  • ①. Pellet tip
  • ②. PKG ball terminal
  • ③. Circuit board
  • ④. Underfill
  • ⑤. Defect analysis (void occurrence)
Circuit board surface polishing

Circuit board surface polishing

Magnified observation of defective area

Magnified observation of defective area

Example mounting reliability connection defect analysis

< Procedure >

①. Subject observation (naked eye, metal microscope, X-rays, ultrasonic flaw detector)
→ Record the information obtained from the detailed observation and external view.
②. Electrical characteristics investigation
→ From the defect items, consider the structure to identify the defective areas, understand the structure, and make observation using X-rays, etc.
→ The current defect is electricity not flowing in the specified terminal.
③. Determine the defect analysis method (Here, defect analysis using cross-section polishing is introduced as an example.)
*This sample is finished using cross-section polishing.
断面研磨品 PKG全体観察
断面研磨品 PKG全体観察
  • ①. Pellet tip
  • ②. PKG ball terminal
  • ③. Connection post
  • ④. Mounted circuit board
  • ⑤. Connection point between product (electrical component) and circuit board
不良部位の拡大観察
不良部位の拡大観察

Cross-section polishing was performed and the electrical characteristics used to narrow down the problem to the terminal where a crack was confirmed between the substrate and substrate post.
The electronic component ball is sufficiently connected.

  • ①. Pellet tip
  • ②. Electronic component solder ball
  • ③. Post
  • ④. Mounted circuit board wiring
不良部位の拡大観察

SEM was used to magnify the view to identify the defective area.

Mounted component general defect analysis

Defect analysis and reliability evaluation

故障解析と信頼性評価

Example defect analysis

ボンディングの接合不良による故障解析の研磨手順

■Sample holder used: Uniaxial oblique holder
■Polishing point: Correctly expose the array cross-section for the area identified using the electrical characteristics.
■Defect description: Terminal open (not connected) defect

< Procedure >

①. Observe the sample
→ Record the information obtained from the detailed observation and external view.
②. Electrical characteristics investigation
→ From the defect items, consider the structure to identify the defective areas, understand the structure, and make observation using X-rays, etc.
③. Determine the defect analysis method (For example, introduce cross-section polishing)
→ Change the polishing recipe while watching the polishing progress and structure area.
故障解析の研磨手順 1

A. Start polishing from the side of the identified terminal.
→ First, the connection wire from the external terminal will appear as a point in the cross-section.

故障解析の研磨手順 2

B. At the beginning, the side of the lead frame containing the pellet tip will be exposed.

故障解析の研磨手順 3

C. As the polishing advances, the side of the tip will be exposed.
Check the cross-wise uniformity.

故障解析の研磨手順 4

D. Thereafter the bonding side will be exposed.
Check the cross-wise uniformity and focus on the terminal you want to observe.

故障解析の研磨手順 5

E. Perform buff polishing, check the state of the connection between the tip and the bonding surface, and then perform the final observation using a high magnification SEM, etc., to check if the defect location matches the electrical characteristics results.

故障解析の研磨手順 6

F. Compare the defective terminal with a good one to observe the structural differences.
→ Defective terminal: Void under the Bd.
→ Good terminal: Bonded under the Bd.

故障解析の研磨手順 7

G. Defective area identified by magnified view using a SEM.

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