What Is a Backing Board?

Backplanes have always been specialized products in the PCB manufacturing industry. The backplane is thicker and heavier than conventional PCB boards, and its heat capacity is correspondingly larger. Given the slower cooling of the backplane, the length of the reflow oven should be longer. It also needs to be forced air-cooled at the outlet to reduce the temperature of the backplane to a safe operating level.

Backplane

(Technical term)

Right!

Backplanes have always been specialized products in the PCB manufacturing industry. The backplane is thicker and heavier than conventional PCB boards, and its heat capacity is correspondingly larger. Given the slower cooling of the backplane,

Definition 1: Ossification area on the back of the somite.
Definition 2: Generic term for the ossified part of the dorsal part.
Definition 3: Large or even ossified part of the back of the body, smooth or textured and setae.
Definition 4: It is installed on the periphery of the support (well circle), so that the ground pressure is evenly transmitted to the support and prevents debris from falling.
Definition 5: A circuit board or frame that supports the interconnection of other circuit boards, devices, and devices, and provides power and data signals for the supported devices.

Backplanes have always been specialized products in the PCB manufacturing industry. The backplane is thicker and heavier than conventional PCB boards, and its heat capacity is correspondingly larger. Given the slower cooling of the backplane, the length of the reflow oven should be longer. It also needs to be forced air-cooled at the outlet to reduce the temperature of the backplane to a safe operating level.

The need for thinner cores and more backsheets has brought opposite requirements to the conveyor system. When a high-power-consumption application card is inserted into the backplane, the thickness of the copper layer must be moderate to provide the required current to ensure that the card can work properly. All of these factors result in an increase in the average backplane weight, which requires that conveyor belts and other conveying systems must not only be able to safely move large-sized raw material boards, but also take into account the fact that they are gaining weight. Because the backplane is thicker than conventional PCBs, and the number of drilled holes is much, it is easy to cause processing fluid to flow out. In order to minimize the amount of liquid carried and to eliminate the possibility of any drying impurities remaining at the pilot hole, it is extremely important to use high pressure flushing and air blowers to clean the borehole.

As user applications require more and more board layers, inter-layer alignment becomes very important. Inter-level alignment requires tolerance convergence. As board size changes, this convergence requirement is more demanding. All layout operations are performed in a controlled temperature and humidity environment. The exposure equipment is in the same environment. The registration tolerance of the front and rear images of the entire area must be maintained at 0.0125mm. After etching, a four-drilling system is used to perforate the inner plate. The perforation passes through the core plate, the position accuracy is maintained at 0.025mm, and the repeatability is 0.0125mm. Then use a pin to insert the perforation to align the inner layer after etching, and at the same time glue the inner layer together. The use of this post-etching perforation method can fully ensure that the drilled holes are aligned with the etched copper plate, forming a strong ring-shaped design structure. However, as users require more and more wiring in a smaller area in terms of PCB routing, in order to keep the fixed cost of the board unchanged, the size of the etched copper plate is required to be smaller, which requires better inter-layer copper plate alignment. Jigs and conveying equipment must be able to transfer large and heavy boards simultaneously.

In addition to drilling holes that require uniform plating thickness, backplane designers generally have different requirements for copper uniformity on the outer surface. Some designs etch few signal lines on the outer layer. On the other hand, in the face of high-speed data rate and impedance control circuit requirements, it is necessary to provide a solid copper foil in the outer layer for EMC shielding. Since users require more layers, it is important to ensure that the defect identification and isolation of the inner etched layer is performed before bonding. In order to achieve effective and repeatable control of the backplane impedance, the etch line width, thickness and tolerances have become key indicators. At this time, the AOI method can be used to ensure that the etched copper pattern matches the design data. Using the impedance model, the line width tolerance is set on the AOI to determine and control the sensitivity of the impedance to line width changes.

Traditionally, passive components have tended to be used on backplanes for reliability reasons. However, in order to keep the fixed cost of active boards, BGAs and other active devices are increasingly designed on the backplane. Component mounting equipment must not only be able to house smaller form factor capacitors and resistors, but it must also be able to operate additional silicon packaged components. In addition, the large-scale backplane requires a large installation equipment bed, and the heavy backplane can also be shifted with fine position tolerances. ^[1]