PCBA Box Build Assembly

PCBA Box Build Assembly

The world of electronics is very vast. There are countless products in the world that contains PCBs inside. Although we know that PCBs are the core of any electronic product but have we ever thought of how their enclosures were made ? Yes enclosure or simply we can say "box" is the mechanical compartment where PCBs reside. These boxes can be in different shapes and sizes. Variety of complexity of mechanical designs of enclosures can show how advanced the product is.

2. PCBA

For example a simple enclosure/box that is rectangular shape, small in size, having small LCD display and 2 push button on front panel and one power socket and temperature sensor probe input connector on rear panel is a simple example of box assembly. There can be multiple or single PCBs fitted inside and a few wire cables inside for interconnectivity.

 

On the other side a complex enclosure is the one having complicated process of dismantling the assembly, having various kinds of wiring harness, special kinds of nuts and bolts like Allen key or star key bolts, having a proper guide book how to open the unit like in hp Synthesized signal generator disassembly, Anritsu or Shimadzu Spectrum analyzer dismantling and other kind of complicated machines disassembly having complicated PCBs mounted / fitted inside.

 

There are numerous gigantic electronic manufacturing companies means OEM like Hp, Dell, Samsung, Huawei and others who have dedicated mechanical engineering teams who are expert in mechanical enclosure designing, fitting sub-assemblies, integration and testing of a final product before it is forwarded to quality control checks and then floating product in  market for sell.

Typical Box Build Assembly Services:

In every electronic product or equipment you would find the box assembly that provides the solid casing, safety and good aesthetic look to the end product. The CEM providing this service usually works on following domain

Simple box for PCB

1- 3D CAD Model Design

There are numerous software available for mechanical design of 2D and 3D modeling. Normally Solid Works and PTC CREO are used by many design engineers and CEM companies hire those mechanical engineering experts having full command on these CAD software. There are too many things like clearances, dimensions, pitch, inner and outer diameter and other to consider in order to make a perfect 3D model that will be used in fabrication or box build assembly.  The design and validation engineers will make sure that 3D models must comply with the standards being set by QC engineers and that when assemblies and sub-assemblies are integrated with each other, they will not become loose, tight and disoriented.

2- Material of Enclosure Selection:

There are various types of materials available for PCB enclosure like ABS plastics, plastic, acrylic plastic, sheet metal and wood. Special dies and molds are made for plastic body making however for sheet metals and acrylic plastics, simple laser cutting can be used.

3- System Level Integration:

The most important service of the box building assembly company is the combination and interfacing of various sub-level assemblies like power supply board, mother board PCB, heat sinks, fans, display panels PCBs, memory card slots, Input/output interface circuits, electromechanical assemblies and many other assemblies that may be the part of overall product. Interfacing requires many things like ribbon cables, multiple or single stranded electrical wire, RF coaxial connectors, wire grips, headers, BNC connectors, lugs, earth or ground connections to metal body, apply thermal paste to heat sinks components, use tie wraps,

4- Product Assembly:

As soon as the sub-assemblies are assembled, now is the time to pack them in final enclosure by riveting, screws hole drilling, tightening nuts and bolts, using washers and mechanical locks on sheet metal plates. The sheet metal plates are done Insulation, polishing,  blasting, cutting, welding, straightening and then finishing and then these plates are combined with each other to form a complete box. After this the subassemblies are placed inside and final screws are tightened to properly secure the enclosure. Many renowned CEMs use too many screws to fasten the top, bottom, side metal sheet covers to make strong and robust body of product as shown in previous figures of HP spectrum analyzer.

5- Programming /Configuring:

Now that the complete product is assembled and properly enclosed, it is time now to do initial factory programming or configurations. Most of the high end electronic equipment require programming like date and time setting, manufacturer codes, system file configuration and BIOS update. This is all done by normally available external LCD screen in most of the products and the program is fed in the memory ROM once and for all. After this OTP (One Time Programmable) chip is ready to do self test whenever the product is turned ON. This self test allows the product to scan its subassemblies for any malfunctions that may be possible and if found OK it goes ahead otherwise it shows error messages. The error message details are usually defined by OEM or ODM in their catalog/user manual for users. The memory ICs like RAMs and other re-programmable SRAM can be used by user to feed their customizable programs to make product function accordingly. Note that these functionalities are only applicable to high end advance electronic equipment or instruments like the one shown in figure below and not for casual/usual electronic products.

6- Labeling and Logo Mark:

Another important task is to emboss or print logo and stamp label on the body of the product as desired. The logo can be a high voltage danger logo with skull or electric arc showing, labeling the power outlets, keypads, display screen readings like volt, ohm, ampere, signal levels, frequency, counter values, etc. The significant label is indeed the logo of the company that shows the intellectual property rights of that particular ODM

7- Testing:

The box build assembly manufacturers must also do final testing to check the functionalities of the product after all above prior steps are done. This test can be anything from (talking about the Function Generator) power on/off test, signal output waveforms analysis, impedance matching test, keypad input testing, frequency, amplitude, DC offset and phase test etc etc.

8- Warehousing:

Next step is to properly store the product in a well maintained warehouse where temperature and humidity is controlled. Proper cleanliness of warehouse should be assured.

 

9- Order from Client:

The next step will be to fulfill the order that is raised from client promptly. Product must be delivered with complete warranty card, user manual, service manual, assembly and disassembly guideline to user, Comprehensive parts list detailing the minute to largest components either mechanical, electrical or electromechanical that is used in the product. Some product service manuals have huge details of components used and even the details of screw and its size, dimension, orientation and placement. The parts list is a tricky thing and every component/part must be given unique identity so it can be traced by trained technicians when dismantling the product when needed. Usually it is recommended that these sophisticated electronic equipment must not be dismantled by common users except for the well trained professional technicians or by service support team of ODM/OEM/EMS.

10- After Sales Services and Repairs:

As the product is now sold to user, the box building assembly company that is usually the EMS or CEM (Contract Electronics Manufacturer) must also provide value added services like repairs, calibration, periodic maintenance under warranty.

Product-Assembly

Conclusion:

Mostly the CEMs are working on the product from A to Z. Like starting from design files either the design files of PCB circuits or 3D design files of box building assembly and completing till the complete product is finished and delivered to user. Even after sales, the CEM provides services as mentioned in paragraph 10 above. Hence it is recommended to choose a CEM that can provide professional services in both electronics and mechanical side considering extensive expertise in above mentioned ten services.