Lead Free Hasl PCB Assembly Service Audio Amplifier Through Hole Prototype Board

Protection and packaging After Assembly

PCBs intended for extreme environments often have a conformal coating, which is applied by dipping or spraying after the components have been soldered. The coat prevents corrosion and leakage currents or shorting due to condensation. The earliest conformal coats were wax; modern conformal coats are usually dips of dilute solutions of silicone rubber, polyurethane, acrylic, or epoxy. Another technique for applying a conformal coating is for plastic to be sputtered onto the PCB in a vacuum chamber. The chief disadvantage of conformal coatings is that servicing of the board is rendered extremely difficult in PCB assembly service.

Many assembled PCBs are static sensitive, and therefore they must be placed in antistatic bags during transport. When handling these boards, the user must be grounded (earthed). Improper handling techniques might transmit an accumulated static charge through the board, damaging or destroying components. The damage might not immediately affect function but might lead to early failure later on, cause intermittent operating faults, or cause a narrowing of the range of environmental and electrical conditions under which the board functions properly. Even bare boards are sometimes static sensitive: traces have become so fine that it is possible to blow a trace (or change its characteristics) with a static discharge. This is especially true on non-traditional PCBs such as MCMs and microwave PCBs.

Test After PCB Assembly Service

After the board has been populated it may be tested in a variety of ways:

• While the power is off, visual inspection, automated optical inspection. XHT guidelines for PCB component placement, soldering, and inspection are commonly used to maintain quality control in this stage of PCB manufacturing.
• While the power is off, analog signature analysis, power-off testing.
• While the power is on, in-circuit test, where physical measurements (for example, voltage) can be done.
• While the power is on, functional test, just checking if the PCB does what it had been designed to do.

To facilitate these tests, PCBs may be designed with extra pads to make temporary connections. Sometimes these pads must be isolated with resistors. The in-circuit test may also exercise boundary scan test features of some components. In-circuit test systems may also be used to program nonvolatile memory components on the board.

Specification

Company Profile

XHT Technology Co.,Ltd located in Huizhou, China.The company is strong and professional technical, with perfect quality assurance system and advances test-analyzed instrument. XHT is one of the Professional PCB manufacturer from China. We have professional PCB designer for your PCB layout requirement. We design single, double, and multi layers , Rigid, flexible, Flex-Rigid printed circuit boards, and PCB assembly.Through data management, XHT has greatly improved production efficiency in a system-driven mode, and achieved completion within 24 hours from order placement to delivery, helping users shorten the research and development cycle. As a promoter and practitioner of Industry 4.0, XHT will accelerate its own digital and intelligent iteration, and actively create a "new lighthouse" for intelligent manufacturing in the electronics industry.

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