Memory Module Manufacturing Part 5
The first step in assembling the memory module is Screen Print. A stencil is used to screen solder paste onto PCBs. The stencil ensures the solder paste affixes only where components will attach. Solder paste is tacky and holds chips in place on the PCB. If a chip is misplaced, it can be removed and the solder paste is cleaned off the board.
PCBs contain several marks called fiducials. These are not part of the circuit but are locators for placing chips. Vision systems in High Speed Automated Pick and Place machines scan the fiducials to dimensionally check and locate where to place chips on PCBs. Pick and Place machines are programmed to know which chips are placed where. The machine picks a chip from the feeder and places it in its appropriate location on the board. The same process occurs for all remaining chips and for any other components on the module. Of all the steps your memory module goes through, this is the fastest. All the chips are placed on a PCB in just a few seconds!
Next, the assembled chips and boards pass through an oven. The heat melts, or reflows, the solder into a liquid stage. When the solder cools, it solidifies, leaving a permanent bond between chips and board. The surface tension of the molten solder prevents the chips from misaligning during this process.
Once the chips are attached, the array is separated into individual modules. Micron team members visually inspect each module. Many modules also undergo additional inspections using automated X-Ray equipment to ensure no unreliable solder joints exist. All Micron Memory Modules meet IPC-A-610 acceptance criteria - the industry standard recognized worldwide.
Micron then tests and tags the modules. We use custom equipment to automatically test performance and functionality. This eliminates any possibility of an operator mistakenly placing a failed module in a passing location. Certain modules are programmed with an identifying "Dog Tag" that your PC will recognize and read.
Finally, the modules are sampled through one last Quality Inspection. They are placed into ESD safe plastic trays or bags and are ready for delivery. Finished product is shipped to the customer. Micron is the memory supplier to the top PC manufacturers in the world.
Much of the success of Micron and its subsidiaries is due to their long-standing commitment to quality. For example, Micron Technology, Inc., uses a unique intelligent burn-in and test system called AMBYX as part of its stringent quality assurance and testing process. The AMBYX system tests chips under varying temperatures, voltages, and operational conditions, providing reliability data on every device made. Our memory manufacturing processes are ISO 9001 certified - the most comprehensive level of certification, in the internationally recognized ISO family of specifications for quality assurance management systems. In February 1997, Micron Technology, Inc. was one of the first companies in the United States to attain certification under the new ISO 14001 Environmental Management Systems Standard. ISO 14001 are the emerging voluntary international environmental management standards, which ensure that organizations have effective environmental systems.
Who else manufacturers memory?
There are only a handful of "true" manufacturers of memory - that is, companies who fabricate the memory chips. These manufacturers sell their chips mostly to major computer manufacturers for use in their systems. In the memory upgrade market, however, there are a number of vendors who claim to be memory manufacturers, but the truth is, these vendors buy the memory chips from a manufacturer like Micron, then, merely assemble the modules. Other vendors in the upgrade market simply buy the modules from a manufacturer, repackage them, and sell them under their brand name. We believe that Micron is the first true memory manufacturer to ship its products directly to consumers.