Integrated Circuit Board

The use of integrated circuits is very interesting, especially when it comes to programmable integrated circuits because of the endless possibilities that a microcontroller can offer. The possible combination and advantages of programmable integrated circuits are only limited to the designer capability. However, intermittent interchange of ICs between the prototype base and the programming board when playing microcontrollers can lead to incontinence and a slight reduction of the interesting part.

As a solution, a number of IC development boards existed which combine prototype and programming together to make it a single unit. Most IC development boards use USB as the primary power supply and programming port. Therefore, no additional power conditioning circuit and programming interface are required to allow the project to proceed. Almost no boards are made as per industry standards with high-end processors and common interfaces that can be used directly for practical applications. However, IC development board has the necessary components to connect boards to various modules and gadgets that are commonly available on the market. Development PCB board mainly uses SMD components to make it compact.

The PCB is made to fit various shields that can be used to further extend the functionality of the development board. The traditional IC development board has small versions which cover almost all of its features and can be installed anywhere in the project. Some advanced boards like raspberry pi can run on an independent operating system which can be used as a microcomputer system with some basic computer functionalities.

PCB Solder Mask

The printed circuit board uses copper as the main conductive path. Since copper has the high probability of reacting with the atmosphere and producing oxides, the conductivity reduces and the PCB performance will be destroyed. Also during the soldering process, the liquid solder may flow and form a solder bridge commonly referred to as two closed traces and lead to short circuit interconnection. To protect the copper from oxidation and to avoid soldering bridges, a thin coating is applied to the traces commonly referred to as solder mask.

There are few types when choosing solder mask. Depending upon the need and cost, appropriate solder mask is selected.

EpoxyEpoxy is a basic and cheap solder mask which is mainly used in low precision and prototyping PCBs. Since epoxy is semi solid in nature, it is usually applied through the silkscreen printing.

DFSM

DFSMs are like dry film photo resists used in copper etching. Prepared PCBs are vacuumed pressed with the sheet of DFSM. The solder pad is eliminated by covering the corresponding area with an anti-UV developer. The settings were then exposed to UV light to cure the DFSM. After a few minutes of exposure, the solder mask is transferred from the sheet to the PCB. The photoresist is then removed with a solvent.

LPSM

This is a liquid solder mask much like an ink which can be spray painted or immersed on a marked laminate. The solder cutouts are done by placing a temporary ink marks which is removed after the solder mask application. The applied PCB are exposed to UV light to dry out the ink. The dried PCBs are cleaned and re-inserted in to the exposure for a final cure.

3 Factors for Faulty PCB Soldering

Reviewing PCB board soldering technology development in the electronics industry, it can be noted that reflow technology has developed fast and stable. How to ensure the quality of PCB soldering is the major concern among electronics manufacturers, so in this article we outline three major reasons for faulty PCB board soldering.

Soldering quality is affected by the solderability of PCB board holePoor solderability of PCB board hole will make soldering defects, which can affect the parameter of circuit components, cause poor stable connection between components and inner layer in the multi-layer board, even worse, the entire circuit will be out of work. The so-called solderability is the property by melting the metal surface, that is, a relatively uniform continuous smooth film is formed by the solder on the solder surface.

Soldering defects caused by PCB warpage During the soldering process, PCB board and components may be warping due to the stress, and then short circuit, deformation and other defects may be caused. Warping is often caused by the imbalance temperature given to the upper and lower layers. Sometimes, large size of the PCB board may be warping due to its own weight. Distance from ordinary PBGA to the PCB board side is about 0.5mm. If components are larger on the board, then it is easily to cause faulty soldering when PCB board restore to its normal shape after cooling down. 

Soldering quality is affected by PCB designIf your board size is too large, the soldering is easy to control, but the printed line length and impedance will increase while the anti-noise ability will decrease, finally the cost will increase. If your board size is too small, the heat dissipation ability will decrease, the soldering is difficult to control, and adjacent lines tend to interfere with each other. Therefore, your PCB board design must be optimized.

Integrated Circuit Board

The use of integrated circuits is very interesting, especially when it comes to programmable integrated circuits because of the endless possibilities that a microcontroller can offer. The possible combination and advantages of programmable integrated circuits are only limited to the designer capability. However, intermittent interchange of ICs between the prototype base and the programming board when playing microcontrollers can lead to incontinence and a slight reduction of the interesting part.

As a solution, a number of IC development boards existed which combine prototype and programming together to make it a single unit. Most IC development boards use USB as the primary power supply and programming port. Therefore, no additional power conditioning circuit and programming interface are required to allow the project to proceed. Almost no boards are made as per industry standards with high-end processors and common interfaces that can be used directly for practical applications. However, IC development board has the necessary components to connect boards to various modules and gadgets that are commonly available on the market. Development PCB board mainly uses SMD components to make it compact.

The PCB is made to fit various shields that can be used to further extend the functionality of the development board. The traditional IC development board has small versions which cover almost all of its features and can be installed anywhere in the project. Some advanced boards like raspberry pi can run on an independent operating system which can be used as a microcomputer system with some basic computer functionalities.

Benefits of Flex and Rigid-Flex PCB

Flex PCB and rigid-flex PCB board allow you to design the circuitry to fit the device, instead of building a device to fit the circuit board. They are largely used in the industry of aerospace, medical and military applications thanks to dependable reliability.

Flex circuits offer multiple advantages, and the following will show you some key benefits of using flex and rigid-flex circuit technology.

Component/Connector Assembly1.Flex circuits can accept any component or connector that can be assembled to a rigid PCB design.2.Integrated ZIF contacts provide simple modular interfaces to the system environment.3.Additional options are available such as, ZIF Connectors, crimped contacts, direct solder to PCB, etc.

Cost Savings1.Thin and flexible polyimide film requires a much smaller area, reducing the overall finished assembly packaging size and material requirement costs.2.Reduced assembly costs are also seen as fewer parts are needed for the final assembled product.3.A simplified PCB assembly processes can reduce assembly errors as the flex circuit can only be installed one way.4.Flex circuits can eliminate wire routing errors, and reduce test time, rework, and rejects.

High Density Applications1.Flex material properties work very well in high speed controlled impedance designs, which allow better control of impedances.2.Flexible PCB allow for narrow lines giving way to high density device population. Denser device populations and lighter conductors can be designed into a product, freeing space for additional product features.

High Temperature Applications1.Flex circuits materials (polyimide) dissipate heat at a better rate than other dielectric materials while providing the added benefits of vastly improved flexibility.2.Exposed to extreme temperature applications (up to - 200C to 400C) is ok.3.Expansion and contraction are minimized when using polyimide material.4.Good chemical resistance to oils, acids, gases etc.5.Flex circuits boards offer excellent radiation and UV exposure resistance.

High Density Interconnect Board

High density interconnect board or HDI board is one of the fastest growing technologies in PCB industry. HDI boards contain blind and/or buried vias and often contain microvias of .006 or less in diameter. They have a higher circuitry density than traditional circuit boards.

There are 6 different types of HDI boards, through vias from surface to surface, with buried vias and through vias, two or more HDI layer with through vias, passive substrate with no electrical connection, coreless construction using layer pairs and alternate constructions of coreless constructions using layer pairs.

HDI technology is the leading reason for electronic products transformation like camera, mobile, computer, pad, etc. Products do more, weigh less and are physically smaller. Specialty equipment, mini-components and thinner materials have allowed for electronics to shrink in size while expanding technology, quality and speed.

As consumer demands change, so must technology. By using HDI technology, designers now have the option to place more components on both sides of the raw PCB. Decreased component size and pitch allow for more I/O in smaller geometries. This means faster transmission of signals and a significant reduction in signal loss and crossing delays.

While some consumer products shrink down in size, its quality remains at its best level. Using HDI technology is possible to reduce an 8 layer through-hole PCB to a 4 layer HDI microvia technology packed PCB. The wiring capabilities of a well-designed HDI 4 layer PCB can achieve the same or better functions as that of a standard 8 layer PCB. Although the microvia process increases the cost of the HDI PCB, the proper design and reduction in layer count reduces cost in material square inches and layer count more significantly.

A Flexible Circuit Coverlay

In the flexible printed circuit board manufacturing process, a flex circuit coverlay or coverfilm is used to protect the external circuitry of a flexible circuit board.

A flexible circuit coverlay serves the exact same function as soldermask that is used for rigid printed circuit boards. The difference with the flexible coverlay is the flexibility required for flexible circuit boards and the required components for durability.

The coverlay consists of a solid sheet of polyimide with a layer of flexible adhesive that is then laminated under heat and pressed to the circuit surfaces. The required component feature openings are mechanically created using drilling, routing, or laser cutting.

Typical coverlay thickness is 0.001" polyimide with 0.001" of adhesive. 0.0005" & 0.002" thicknesses are available, but only used as needed to meet specific design requirements. 

Polyimide coverlay and flexible liquid photoimageable (LPI) solder mask are two primary options for encapsulating the external circuit layers of a flex circuit board.

Of the two, polyimide coverlay is the most commonly used and preferred solution throughout the industry. It provides a much more robust and durable solution with very good flexibility and a high dielectric.

Flexible LPI solder mask is essentially the same formula that has the same capabilities and is applied in the same manner as on rigid circuit boards.