PCB에서 acid trap 이란? (PCB 제조에서 발생하는 문제)

아래 링크를 참고했다.

resources.pcb.cadence.com/blog/are-acid-traps-still-a-problem-for-pcbs-in-2019-2#:~:text=An%20acid%20trap%20is%20simply,from%20a%20board%20during%20manufacture.

Are Acid Traps Still a Problem for PCBs in 2019?

What is a PCB acid trap?

An acid trap is simply any sharp corner in your trace pattern that could trap the harsh chemical etchants used to strip excess copper from a board during manufacture. When etching solution pools in a corner, there’s a risk of it tunneling through the etchant resist and corroding your traces and creating a faulty connection or open circuit.

 

acid trap을 요약하면 아래와 같이 분기하는 부분에 날카롭게 파인 코너 부에 etching(에칭) 가공시, 의도하지 않게 설계와 다르게 가공될 수 있다. (과도하게 Trace가 산화 되는 문제 등) 이러한 문제는 회로를 Open(단선) 또는 Short(단락, 합선)을 일으킬 수 있음.

 

즉 이 문제를 줄이기 위해서는 부드럽게 연결되지 않은 홈 부분의 이음세를 부드럽게 해주어야 한다.

https://www.raypcb.com/common-pcb-design-mistakes/

 

 

2. Acid Traps Acute Angle

During the PCB design process, the design engineer can unknowingly makes a mistake. This mistake is that the two traces meet/cross each other at “acute angles” i.e less than 90º . As a result, the corners are made in the trace crossing point that can “trap” acid inside it. The acid referred here is the PCB etching solution used to etch away unwanted/excess copper from the PCB and only useful copper is left for making tracks/traces. This acid / etching solution is commonly available Ferric Chloride or Hydrochloric Acid.

 

The “acid trap hole” is another similar thing that arises due to very less gap between the trace and via. This will cause the space or pockets to form and retain the acid inside.

 

These acid if trapped for long time, can eat away copper trace and hence creates open circuit that can render the PCB board defective. The possibility of acid traps in multilayer PCB is very high. Recent advancement in etching method (photo activated etching solution) of PCB has made this issue trivial but still best practice must be ensure to avoid acute angle traces.

 

(간단 요약)

두 Trace가 "acute angle", 즉 90º 미만에서 서로 만나거나 교차할 때, Etching 작업 시, 모서리 사이에 좀 과한 산 용액이 남게 되어 과하게 부식이 될 수 있다. (주로 사용되는 etching 성분은 염화철 또는 염산)

"Acid trap hole"은 trace와 via 사이의 간격이 매우 적을때 발생. 
이 hole로 인해 산 용액이 해당 자리에 머물며 부식 시킴. 이는 Trace를 부식시켜 Open(단선) 시킬 수 있음

 

 

 

 

 

 

 

 

 

아래 포스팅 참고

www.wellpcb.com/acid-trap-pcb-via.html

Acid Trap PCB Via-Ultimate Guide On All the Things You Need to Know