High-speed PCB design guidelines flour
The first article high-density (HD) circuit design
In this paper, many people consider chip scale BGA encapsulation as required by the portable electronic products of a space restrictions feasible solution, it also satisfy these products higher requirements of function and performance. For portable products high-density circuit design for assembly process should consider.
When the market for today worth promoting development electronic products, performance and reliability is the priority. In order to compete in the market, developers must also pay attention to assembly efficiency, because it could control the manufacturing cost. Electronic product technical progress and growing complexity is producing the higher density circuit manufacturing method needs. When the design requirements SMT, dense spacing and vector encapsulates the integrated circuit IC, may require has a fine line width higher density is dense spacing circuit board. But, in the future, some have in supply micro bypass hole, sequence assembly circuit board company is a large investment to expand capacity. These companies realize portable electronic products to more small encapsulates the current trends. Sheet is communication and personal computing products industry was enough to lead the global market.
High density of electronic product developers more and more be several factors challenge: physical complex components of pins on more dense spacing, financial mounted must be very precise, and environmental many plastic packaging absorption of moisture, cause the rupture during assembly processing. Physical factors including installation process complexity and the reliability of the final product. Further financial decision must consider product will be how to manufacture and assembly equipment efficiency. A fragile pins components such as.50 0.020 "with usd mm with 0.016" pin on SQFP spacing of quad, probably in pack to maintain a constant rate of the assembly process to assembly experts suggest a challenge. The most successful development plan are those who have implemented the circuit board design process qualification authentication of guidance and craft pad geometric shapes.
In the environment, welding plate geometric shape, it may be different on the installation of electronic parts used welding type. When possible, welding plate shape in a to use should the installation process transparent way to define. Whatever parts is installed on board side or both sides, undergo peaks, backflow or other welding, pad and parts size should be optimized, to ensure proper welding point and inspection standards. Although welding plate design is in the size defined, and because it is part of the PCB circuit geometry, they can be productive level and by plating, corrosion, assembly or other conditions related tolerance limit. Productive with resistance welding layer also the use and in resistance welding aligned with conductor design related between orientation.
1, welding plate requirements
International electronic technology Commission (IEC) Eletrotechnical 61188 standards of International top of the welding rounded or realize the pad bump conditions the needs of different goals. The new international standards for developing confirmed two pad shape the basic method: provide information
1.) based on industrial component specifications, circuit board manufacturing and component placement accuracy ability. Precise data These welding plate shape confined to a specific components, a logo pad shapes of Numbers.
2.) some equation can be used to change the given information, in order to achieve a more stable welding connection, it is used for some special cases, in these cases for mounted or install equipment in determining pad details than when the accuracy is that more or less difference.
This standard is used for pasted on various pin or components terminal pad defines the largest, medium and minimum material conditions. Unless otherwise specified, this standard will all third "hope target" tags for level, level 2 or 3.
Level 1: the biggest - used for low density product application, "the biggest" pad for wave or flow welding conditions without pin slices of components and a pin fins of fractal components. For these components and inward "J" type pin the geometry of components configuration for manual welding and reflow soldering provide a wider process window.
Level 2: medium - with the medium level element density of product can consider adopting this "medium" welding plate geometric shapes. And the IPC - SM - 782 standard pad geometric shapes are very similar, for all components of medium welding plate type allocation for reflow soldering process provides a steady welding conditions, and should be no pins
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