Memory manufacturing process
Production of GOODRAM memory modules begins with the automatic transfer of PCBs, also known as multiblocks, to a surface mount line.
There, a Panasonic SPG machine, used for paste printing through a precision screen, applies Alpha OL107F-A solder paste to the board. The printing accuracy is 12.5 µm (CPK = 1.33). For comparison, the finest human hair is 0.2 mm. This is important because the fine passive components and modules will be placed right next to each other.
Specially designed screens in the DEC VECTORGUARD™ system tailored for each type of board are laser-cut, which prevents excessive solder paste consumption and allows the paste to be applied only in designated areas of the board.
However, before the machine begins to apply the paste, the camera scans the wafer and screen looking for reference points on the wafer, known as Fiducials, precisely positioning the screen relative to the wafer. The entire process, from the entry to the exit of the wafer, takes about 15 seconds and is controlled by a computer throughout. A constant temperature and humidity are maintained in the machine, and the screen is systematically cleaned.
PCB multiblocks with solder paste applied, are subjected to inspection in the process of automatic inspection through the SPI machine from the “Solder paste inspection” PARMI SIGMA-X using a fast and precise laser for inspection. The inspection takes a few seconds. The machine is capable of verifying a 60cm2 area in one second with paste printing up to 10 µm x 10 µm. The machine’s task is to verify the precision and correctness of the solder paste application on the PCB. This, after verification, is transferred to the assembly of passive components, which is carried out in Panasonic NPM-D2 machines.
NPM-D2 machines have a modular design. This means that each module has two assembly heads in a configuration selected according to the type of product.
In each of them there are suction nozzles, the so-called “nozzles”, which are used to retrieve components. Each component, which is taken from the rolls placed on the so-called “feeders”, is subjected to a verification process by the machine vision system consisting of 2 cameras and a height sensor. The capacity of the NPM (3 modules) is 360,000 components per hour, which means that the machine needs only 0.01 seconds to apply one element (component). Between 4,500 and 7,000 GOODRAM Industrial modules can be produced daily on the production line.
The same machines are also used to assemble memory chips, so-called “memory dice,” which come in two types of housing: TSOP and BGA. Memory dice can be fed from rolls, as well as from special trays. These components are also 100% inspected by the machine’s vision system.
Surface mount machines are fully safe for operators and the production process itself. A sudden power outage does not damage the workpiece that is currently being assembled, as when the machine resumes operation, it automatically starts from where the outage occurred.
The memory production process ends with the soldering of the assembled packages.
This is done in a special ERSA HotFlow 2/14 SMT production furnace, with 7 top and bottom soldering zones and 2 cooling zones for reflow soldering. During this process, the solder paste, consisting of a suspension of tin balls, silver and copper in flux, under the influence of temperature forms a solid connection between the board and the components, the so-called “solder paste” is formed.
Depending on the solder paste used and the components applied to the board, a special soldering profile is set via a specialized instrument – ECD SUPER MOLE GOLD 2 profilometer. The temperature in the furnace is about 260°C and varies in each zone. The wafers passing through the furnace move at a speed of 60 to 120 cm/minute, after which the wafers go to the buffing machine, from which they are further transported to the process of automated visual inspection AOI from. “Automatic optical inspection.”
Then the panels, via the highly efficient AOI PARMI Xceed machines, are subjected to an automated inspection using a laser, the machine checks the correctness of the soldering and the quality of the welds, as well as the height of the placement of passive components, and the mechanical damage of the PCB soldermask is verified. The machines operate at a very high capacity of 65cm2/s for components with a dimension of 14 µm x14 µm. For BGA bones, modules are checked in an X-ray machine, X-Ray, which works in 3D.
The culmination of the assembly process is the selection conducted by the AOI device via an automated magazine. The AOI separates PCB multiblocks into those without defects, known as PASS, and multiblocks where a non-conformance has been found, known as Fail.
After this stage comes the EEPROM programming, where the SPD program and lot number information is loaded. The next stage is the functional test, where computer operation is simulated on stands specially designed by Wilk Elektronik, and the memory is subjected to dynamic loads. On separate functional workstations, in turn, the compatibility of individual products is tested. The system used in RAM verification was developed from scratch by the company’s Development Department. The developed software is an operating system integrated with network card drivers, communication protocol and memory management system. This solution makes it possible to indicate a possible defect even in a single memory chip. In addition, the software takes full advantage of the test platform’s capabilities, forcing the maximum load on the memory system. The conditions created are designed to test the module under conditions of maximum duty cycle load. On separate functional stations, in turn, the compatibility of individual products is tested.