Manufacturing in Poland was a long-term goal of the company. That’s why in 2003, Wilk Elektronik S.A. started producing RAM modules there. At its new headquarters in Łaziska Górne the company manufactures products of the highest international quality. The decision was taken to equip the production lines with Fuji machinery, because they have been recognized for years as the best in their class, setting the present-day production standard.

Production in close-up

The production of memory modules starts with a feeding device, which transfers printed circuit boards (PCB), also known as multiblocks, to the surface mounting (SMT) line.

The next step consists of printing the soldering paste. Wilk Elektronik S.A. applies DEK Infinity equipment, which through a precisely made screen places on PC boards a special soldering paste, at the point where passive and active (memory chips and EEPROM) elements are fastened. The precision of printing is 25 µm (CPK = 2.0); by comparison, the thinnest human hair is 0.2 mm. This allows the placing of very tiny passive elements and memory chips very close one to another.

The specially-designed screen makes it possible to prevent the placement of an incorrect amount of soldering paste and to locate it in the appropriate places. Before applying the paste the PCB and the screen are scanned by a camera, which looks for reference points – in order to set the screen precisely towards the PCB. Next the paste is applied. The whole process, from the entry to the exit of the board, lasts a dozen or so seconds and is controlled throughout by computer. A constant temperature and humidity are maintained in the machine, and the screen is regularly cleaned.

After leaving the machine, the multiblocks are inspected under a microscope.

The checked board is next transferred for the assembly of the passive elements, which takes place in a FUJI CP-643E machine, known colloquially as a chipshooter. Its capacity is 42,000 components per hour, which means that to attach one element the machine needs only 0.09 of a second. The machine has as many as 20 heads, each equipped with a “small head” that contains in turn 6 smaller suction nozzles used for collecting the components. The process of assembling the passive elements starts from scanning the multiblock by camera, which searches for reference points. Next, the so-called feeders transfer the required elements from rollers that have already been set in the machine by the operator. The components, which are defined in the machine’s program, are subject to a process of verification by the machine’s video system. It checks if the components taken from the rollers are exactly the same as in the program. Only those that have passed the verification process are placed on the PC board. The FUJI CP-643E is also used for placing the EEPROM devices. When this process ends, the next stage of production inspection takes place.

The next process consists of the assembly of the memory chips. Both TSOP and BGA chips are placed by the same machine, a FUJI QP351E – MM, known colloquially as a “pick and place”.  This process, just as with the two preceding ones, starts with searching for reference points, before the memory chips are fed on special trays or rollers by a special unit called an MTU, or by electric feeders. Also at this production stage, the full process of elements verification is performed by the machine’s video system.

Similarly to the earlier stages, the process is checked after the assembly of the memory chips. At that time small manual corrections can be made; however, this is not necessary in practice. The high class of the machines eliminates the likelihood of any errors.

The machines used for surface assembly are completely safe for their operators, and the production process is secure. Even a minor power cut will not damage the element assembled at a given point, because after restarting the machine begins automatically from the place where production was interrupted.

The process of producing memory chips ends with the soldering of the sited elements, which takes place in a special myReflow oven, made by Vitronics – Soltec. It contains 7 soldering zones and 3 cooling zones, where reflow soldering takes place. At that time the solder paste changes into an alloy containing mostly tin, which permanently connects the PCB with the components. Depending on the applied paste and elements placed on the board, a special soldering profile is set. When lead-based pastes are applied the temperature in the oven is approximately 215 Celsius degrees, while in the case of lead-free pastes it is 235? C. The boards passing through the oven move at a speed of 60 to 120 cm a second, after which a special discharging device deposits the products in containers. From there the modules pass on to visual inspection, where the accuracy of the soldering and the quality of the seams are checked under a microscope. In the case of the BGA chips the modules are controlled in a 3D X-Ray device, which makes it possible to scan even a single BGA chip and perform a volume analysis by dividing it into layers.

The final stage of production is the marking of the memory chips with a Vectomark Compact laser. This does not, however, mean the end of the efforts to ensure the highest product quality for our company. After leaving the production line the modules are subject to a series of tests. Electric tests are carried out to check the quality of the soldering connections. The memory modules are also programmed at that time – the memory configuration and number of series are written in the EEPROM. Any memory modules that depart from the test requirements are sent to the RMA repair stands, where they are subject to very thorough inspection and possible correction.

Functional tests are conducted at stands, which have been specially designed for Wilk Elektronik S.A., where the memory module’s operation in a computer is simulated. This process allows the detection of memory chips with weaker parameters, which are later replaced. The compatibility of separate products is tested at additional stands.