Technical Glassblowing, what’s involved?
Our Multi-lab QuartzTec facility in Scotland has some of the best trained technical glassblowers in Europe. Working with hard glass such as quartz requires a different skill set from softer glass types used in scientific and art glassblowing.
The main difference is the processing temperatures, the temperature where glass becomes “pliable” enough to work or form. Quartz glass only becomes workable at temperatures in excess of 1700 degs C, where softer glasses such as borosilicate can be worked on around 500 degs C.
There are also numerous types or standards of quartz glass and this can also have an effect on how the products are manufactured.
We support numerous high tech industries such as Semiconductor, with our guys in Scotland manufacturing products for some of the most advanced silicon chip producers in Europe. The quality of the quartz glass used is therefore very important to ensure there is no risk of excess levels of impurities leaching from the glass into our customer’s processes. What is also important is the equipment and tooling used, and the methods deployed in the manufacturing process. These also can have an effect on the final quality of the produce shipped from our facility.
So what type of products do we make and what’s involved in the manufacturing process?
This week we manufactured a process tube used by one of our Semiconductor customers, the following gives an overview of part of the process and also some of challenges our glassblowers face.
This particular tube is used by our customer in one of their Diffusion furnaces. The tube will be exposed to operating temperatures around 1100 degs c and be used to “grow” insulation layers onto their silicon wafers. External quartz chambers and injectors are used to mix hydrogen and oxygen which is then fed into the tube and deposited onto the silicon wafers via a “shower like effect” from the top of the tube.
Compiled by: James Rodgers Senior Glassblowing Supervisor, Multi-lab QuartzTec Ltd
James Graham Senior Glassblower, Multi-lab QuartzTec Ltd
The tube being polished on a 500mm bore lathe. All burners being used are made from quartz glass and not any type of metal; this substantially reduces the chances of impurities migrating from the burners into the quartz. The 12” ring burner is also water cooled. After this process the tube will be annealed to remove all strain before the next process steps can begin.
Annealing is very important as any strain left in the tube can cause the bulk glass material to crack or break.
Our Bench department preparing the tube for the welding of a double baffle onto the top of the tube
Once the plate has been tacked in position it can now be fully welded.
One glass blower welds from outside, while one will use a long quartz burner on the inside of the tube to fully fuse the weld.
Both glassblowers will complete the welding using carbon rollers to create a smooth finish between the baffle and tube.
The tube is now ready for the outer spigot’s and gas injectors to be added; again two bench glassblowers will work on the tube in this operation.
We use a welding fixture to ensure the spigots and injectors are placed in the exact position prior to welding.
The tube is then removed from its fixture and fully welded
Once the welding is finished the tube is sent for Annealing again.
It will then go for an acid wash to remove the white smoke deposits left from the welding process
It can now have a final polishing in the lathe department
The remaining components are welded in place and then fire polished before annealing at 1120 degrees. Further in-line quality checks are performed before moving to our machine shop for further processing.
Finally the tube will be washed in our acid room and passed to our quality department for final inspection
A quartz fabrication company is only as good as the capabilities of its staff. This is a highly skilled profession and probably the only “craft” industry deployed within the silicon chip manufactures supply chain.
Multi-lab QuartzTec has the best glassblowers in Europe and are ready and willing to take on any new challenging projects thrown at them!