Gold Finger Corrosion Resistance via Outer Lead Plating
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Solution Overview
Problem
The existing gold plating method for gold fingers on electro-optical circuit boards results in poor reliability and inability to pass Mixed Corrosive Gas (MFG) tests due to exposed copper and incomplete gold coverage, leading to inadequate corrosion resistance.
Innovation Solution
A method involving electrical connection of gold fingers using outer leads, followed by soldermask coating, gold plating, etching the outer lead, and additional soldermask coating to ensure all sides of the gold fingers are plated with gold, thereby enhancing corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the lead is removed manually or etched by wet film at the front end of the gold finger, then the gold finger can be obtained with copper exposed, but the reliability is poor and the gold finger cannot pass MFG test
Solution Approach 1:
The patent applies preliminary action by extending the lead beyond the gold finger area before gold plating occurs. This extended lead portion is then etched away after plating, but the preliminary extension ensures that the lead is positioned correctly to allow complete gold coverage of the gold finger front end, preventing copper exposure and improving reliability.
Solution Approach 2:
The patent inverts the conventional approach by not removing the lead at the front end through manual or wet film etching. Instead, the lead is extended beyond the gold finger, gold plated over it, and then the excess lead is removed through controlled etching. This inversion ensures complete gold coverage and eliminates the reliability issues associated with incomplete gold plating.
2Ease of manufacture
If the lead is removed manually or etched by wet film, then the gold finger structure is obtained, but the gold coverage is incomplete and copper is exposed
Solution Approach 1:
The lead is preliminarily extended beyond the gold finger area before gold plating, ensuring that the entire gold finger front end will be covered by gold during plating. This preliminary positioning eliminates the precision problems associated with manual or wet film etching methods.
Solution Approach 2:
The extended lead acts as an intermediary that facilitates complete gold coverage. By extending the lead beyond the gold finger, it serves as a sacrificial element that ensures gold is deposited over the entire gold finger area, and the excess lead is subsequently removed through controlled etching.
3Productivity
If the lead is disposed at the front end of the gold finger, then the gold finger can be manufactured, but the lead must be removed which complicates the process
Solution Approach 1:
The lead is preliminarily extended beyond the gold finger area, which simplifies the overall process by eliminating the need for manual or wet film etching. The extended lead configuration allows for more efficient gold plating and subsequent controlled etching, reducing process complexity despite the additional initial step.
Solution Approach 2:
The excess lead is extracted after gold plating through controlled etching. By extending the lead preliminarily and then removing only the excess portion after plating, the process becomes more efficient and less complex than attempting to remove lead before plating, as the gold coverage is already secured.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method improves corrosion resistance by ensuring all sides of the gold fingers are plated with gold, addressing the reliability issues and enabling the gold fingers to pass MFG tests, while eliminating the need to remove leads from the front end.
Implementation Method 1
electrically connecting all the gold fingers of the electro-optical circuit board by using an outer lead, wherein the outer lead is disposed on both sides of the guide line
Implementation Method 2
performing soldermask coating on areas outside the outer lead
Implementation Method 3
plating gold on the gold finger
Implementation Method 4
plating gold on the gold finger
Implementation Method 5
etching the outer lead
Data Source
AI summary
Provided is a method for improving the corrosion resistance of a gold finger, which is applicable to an electro-optical circuit board including gold fingers, wherein a guide line is arranged at a root portion of the gold fingers of the electro-optical circuit board. The method comprises the following steps in sequence: 1) electrical connection: using an outer lead to electrically connect all gold fingers of a electro-optical circuit board; 2) solder resistance: performing solder resistance on an area other than the outer lead; 3) gold plating on the gold fingers; 4) etching of the outer lead; and 5) solder resistance: performing solder resistance on a vacancy after etching of the lead. In the method, an outer lead is arranged to electrically connect all gold fingers of a electro-optical circuit board, so that all sides of the gold fingers are plated with gold, thereby significantly improving the corrosion resistance of the gold fingers.