There are many applications use golden BOX package in optical devices, BOX has two categories of airtight and non-airtight. In the airtight BOX, there is a sapphire window on the light outlet. The purpose is to form an hermetic cavity with the shell. Below is the drawing of the sapphire window which often used in the hermetic golden box package.
The sapphire window is generally not directly attached to the outer metal shell of the BOX, but through a stepped metal ring. In this way the sapphire window is fixed and the metal and the sapphire window are hermetically welded, then the metal is welded with the golden BOX. After that, it can be welded with the adapter metal ring of the ceramic sleeve of the capillary optical fiber.
The combination by stages can gradually alleviate the stress of the hermetic cavity at different temperatures. And it has sufficient stress release space. It is convenient to make a universal interface with different types of optical fiber connector.
The sapphire window is usually welded on the golden BOX shell, then do the whole gold plating. After the plating, the front face is polished to remove the surface coating. The gold plated box will be taken to the optical module factory for optical chip packaging, coupling, welding optical fiber adapter, upper cover welding and so on.
If the plating is removed by light outlet grinding, the grinding process has burr, and the process node of polishing and burr removal is also needed after grinding. Generally speaking, burrs are produced on both sides of the corner. Mass production to polish and deburring, is a laborious work.
To save this process, you can open a mold to add a front chamfer for the light outlet. With this chamfer, the grinding resistance will be reduced, and the burr itself will be greatly reduced. It can save the subsequent grinding time and save the prickle process.
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