{"id":3428,"date":"2023-09-22T12:22:10","date_gmt":"2023-09-22T12:22:10","guid":{"rendered":"https:\/\/smans.falkor.alcor.cloud\/?post_type=knowledgeportal&p=3428"},"modified":"2024-01-25T05:05:45","modified_gmt":"2024-01-25T05:05:45","slug":"why-step-stencils-are-indispensable-in-your-pcb-assembly-5","status":"publish","type":"knowledgeportal","link":"https:\/\/smans.com\/en\/knowledgebase\/why-step-stencils-are-indispensable-in-your-pcb-assembly-5\/","title":{"rendered":"Why Step Stencils are indispensable in your PCB assembly"},"content":{"rendered":"

Miniaturization of electronic devices and components is a real trend. Designers are constantly working on the edge of the physical limits of manufacturability. As a result of this the apertures in stencils are always getting smaller. Who still remembers the times that a chip component of 2 by 3mm was really small? Nowadays components of 0,2 by 0,4mm are no exception!<\/p>\n

As soon as the design is made and the PCB\u2019s and components are purchased, assembling all the parts on a production line is the next mayor step. In this step stencils play a very important role.<\/p>\n

\"PCB

Miniaturisation of PCB components over the years.<\/p><\/div>\n

<\/h2>\n

Traditional stencils vs. Step Stencils<\/h2>\n

The common traditional stencils have a certain thickness along their entire surface. Because of miniaturization an increasing need for stencils with areas of lesser or more\u00a0 thickness has grown.
\nThese type of stencils are called stepped stencils.<\/p>\n

The minimum dimensions of the stencil apertures are depending on the stencil thickness. Smaller apertures require thinner stencils. As a result the choice of solder paste has to be reviewed.<\/p>\n

 <\/p>\n

\"Stepped

Example of Step Stencil<\/p><\/div>\n

\"Step

–<\/p><\/div>\n

<\/h2>\n

The importance of a solder paste<\/h2>\n

Solder paste is a mixture of fine grain solder powder and a gel flux. A solder paste is continuously subject to evolution. The grain size of the solder paste determines the filling of the apertures. The thinner a stencil, the better the release of paste from the stencil and the better the transfer of paste to the PCB will be.<\/p>\n

Two decennia ago the standard powder in solder paste had a grain between 25 \u2013 45 \u00b5m, nowadays the grain size has dropped to 15 -25\u00b5m.<\/p>\n

The current solder paste machines have to be able to print complex electronic boards with a repeatable accuracy and very high precision. A robust, stable and high technological machine design is crucial in this process.<\/p>\n

To excel in PCB assembly with the ESE stencil printer<\/h2>\n

The US-X series of stencil printers of the renown South Korean brand ESE has it all to fulfil and even surpass the highest production requirements.<\/p>\n

The hart of the machine is their unique and robust printing table which has 4 ball screws along with 3LM guides. This design is unique and crucial and enables stable print accuracy of within 10\u00b5m and these are combined with a 12,5\u00b5m repeatability.<\/p>\n

\"Print

ESE\u2019s robust, accurate and unique design print table<\/p><\/div>\n

ESE\u2019s US-X series is a very comprehensive machine with some very interesting features:<\/p>\n