Engineering Solutions
PCB Design Capablity
PCB design is the process of creating the layout (physical arrangement and electrical connections) for a Printed Circuit Board (PCB) using specialized software. It involves placing electronic components and routing conductive copper traces on a non-conductive board to mechanically support and electrically connect them.
PCBA123 have three professional PCB design engineers who have multinational companies’ working experience and rich practical experience. PCBA123 design and develop all products by its own engineers. We can also customize for customers’ require.
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Max. PCB design layer
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38
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Max. PIN quantity
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63,000
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Max. quantity of design components
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3,600
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Min. trace width/space
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2.4mil/2.4ml
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Min. hole aperture
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mechanical drill: 6mil laser drill: 4mil
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Max. BGA quantity
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48
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Min. BGA pin distance
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0.3mm
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Max. BGA pin quantity
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2912
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Highest speed signal
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25Gbps/28Gbps
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For PCB pad design: a well-designed and manufactured printed circuit board (PCB) is required for optimum manufacturing yields and product performance. Two types of land patterns are used for surface-mount devices: 1) solder mask-defined (SMD) pads have solder mask openings that are smaller than metal pads, and 2) nonsolder mask-defined (NSMD) pads have solder mask openings that are larger than the metal pads. Maxim recommends the use of NSMD pads because they provide a larger metal area for the solder to anchor to the edges of the metal pads. NSMD improves the solder joint reliability. Only one type of a pad (NSMD or SMD) and one type of pad surface finish should be used at a given footprint. Figure 2 illustrates the NSMD and SMD land pattern design.
Land pattern design should follow Maxim’s 90-xxxx series documents corresponding to the specific package code.
PCB Design for Exposed Pads (Thermal Pads)
Thermal pads on the PCB should be designed to take advantage of the exposed pads of the packages provided. For a single-layer board, a thermal pad should be connected to a large surface pad, so that heat can be dissipated through the surface pad. For a multiple-layer board, thermal via(s) should be placed under the thermal pad, so that heat can be dissipated to other metal layers to take advantage of metals in the those layers. The thermal via(s) design should be optimized based on PCB manufacturer capability and other design limitation.
PCB Surface Finish
Organic solderability preservative (OSP), electroless nickel immersion gold (ENIG), electrolytic nickel gold, electroless nickel electroless palladium immersion gold (ENEPIG), immersion silver, and immersion tin finishes are used in the industry. OSP and ENIG are recommended for applications that require drop test reliability.
Stencil Design Guidelines
The stencil thickness and pattern geometry determine the precise volume of solder paste deposited onto the device land pattern. Stencil alignment accuracy and consistent solder volume transfer is critical for uniform solder reflow. Stencils are usually made of stainless steel.
Stencil thickness: 4- or 5-mil thick stencil is recommended for 0.50mm pitch packages. Package pitches > 0.65mm can accommodate a 6-mil thick stencil.
Stencil fabrication: Laser-cut with electropolish for better release than the regular laser-cut stencil.
Stencil aperture: Tolerances must be tightly controlled.
Walls of the apertures should be smooth, with rounded corners and a trapezoidal cross-section enhance the release of solder paste from the aperture.
Stencil Design for Exposed Pads (Thermal Pads)
The exposed pad solder land can be segmented into a pad array. The pad array should be created by segmentation of a full copper area by solder mask webbing. The segmented PCB design facilitates the solder paste flux out gassing during reflow, thereby promoting a lower voids percentage of the completed solder joint. At the same time, the maximum size of a single solder void is limited by the dimensions of a single matrix segment. Figure 3 shows an example of a solder mask design for an exposed pad.
