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Newest Fine Pitch PCB Assembly Solution Updated for 2021

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Fri, Sept 03, 2021

Fine pitch PCB assembly means assembling the PCBs where the center-to-center distance between adjacent SMD pads and solder balls (BGA pins, IC pins, connector pins...) is extremely small. In other words, the components are close together on a printed circuit board, and the high-speed and functional mounting machines for SMT assembly should have fine-pitch capabilities and accurateness.

What is Fine Pitch PCB Assembly

fine pitch PCB assembly

So what is the exact center-to-center distance between the pads and solder balls on the PCB? Some say the distance is within 0.7mm, some say within 25mils (0.625mm), and some say within 0.5mm. At PCBONLINE's assembly fab, the fine-pitch parts it can assemble on PCBs have a pitch within 0.5mm, and the smallest passive footprint it can handle is 0201 (0.02inch×0.01inch, or 0.5mm×0.25mm).

In fact, in the electronics assembly world, the smallest fine pitch component has the 01005 footprint, and the smallest CSP (Chip Scale Package) devices have only 0.3mm pitch. We call surface mount assembly to this level the ultra-fine pitch assembly.

Components for Fine-Pitch PCB Assembly

Electronic components for fine-pitch PCB assembly can be SMDs, ICs, BGAs, QFPs, and so on, as long as the center-to-center distance between the adjacent pads or solder balls is within 0.5mm. Surface mount devices for fine-pitch assembly are usually 0201, 0402, and sometimes 0603. For fine-pitch components that have solder balls, such as fine-pitch BGAs (FBGAs) and ICs, the distance between the adjacent solder balls is within 0.5mm. For example, the distance between the adjacent pins of the fine-pitch IC as below is 0.3mm.

fine pitch IC for fine pitch PCB assembly

SMT Stencils for Fine-Pitch Assembly

SMT stencil for fine pitch assembly

SMT stencils for fine-pitch assembly are laser-cutting stainless stencils with apertures for the fine-pitch PCB pads. As the fine-pitch SMDs are so small, the pads on the PCB are also small, so solder paste printing through the small holes on the PCB pads is a challenge.

Due to stress concentration, solder paste may be insufficient on the fine-pitch ICs and QFPs. For 0402 and 0201 SMDs, solder paste can be distracted and insufficient as well. Fine-pitch assembly fabs have to specially design the SMT stencils. The apertures cannot be the exact shape and size of the PCB pads.

PCBONLINE designs the apertures of the fine-pitch ICs and QFPs to have the round ends, and the apertures of the 0402 and 0201 SMDs to be square and a little larger than than the pads. This effectively solves the poor soldering problem in fine-pitch assembly. For more SMT design tips, you can refer to 5 Best Tips to Create Openings on PCB Stencils in 2021 - 100% Useful.

Pick-and-Place Machines Having Fine-Pitch Assembly Capability

If you are looking for a fine-pitch PCB assembly fab, you should know the SMT assembly capabilities of its pick-and-place machines -- high-speed assembly machine and functional assembly machine. For fine-pitch assembly, the high-speed assembly machine should have the capability to pick and place 0201 SMDs, and the functional assembly machine should be able to pick and place FBGAs, QFPs, etc.

Fine-Pitch PCB Assembly Fab Recommended -- PCBONLINE

PCBONLINE's assembly fab has fine-pitch PCB assembly capabilities. Below is PCBONLINE's PCB assembly services capabilities:

Placement accuracy
±0.035mm (Cpk≥1)
Min. component size
0201
PCB thickness
0.3mm to 4.0mm
Min. board size
50mm×50mm
Max. board size
1,200mm×370mm
Max. square part size
74mm×74mm
Max. component height
25mm
Max. rectangular part size
50mm×150mm

The 30 SMT lines of PCBONLINE's assembly fab are equipped with Yamaha high-speed assembly machines and functional assembly machines.

SMT machine for fine pitch PCB assembly

PCBONLINE has decades of ≤0.5mm fine-pitch PCB assembly experience for clients around the globe. In fact, PCBONLINE provides turnkey fine-pitch PCB assembly. The PCB manufacturing, SMT stencil designing and manufacturing, fine-pitch component sourcing, and fine-pitch PCB assembly can be done cost-effectively under one roof.

Besides the quality and cost-effective fine-pitch PCB assembly, solution experts at PCBONLINE provide one-on-one engineering support from the fine-pitch PCB designing to batch PCBA manufacturing and testings. Now get an instant quote for fine-pitch PCB assembly online, or contact PCBONLINE by email or online.

Four-Terminal Sensing to Test Fine-Pitch PCB Assemblies

Fine-pitch PCB assemblies are used for high-density applications with high requirements for circuit performances and precision, and they are often used in military, space, automotive, and medical applications. According to IPC 9252 requirements, the Kelvin four-terminal sensing should be conducted to PCBAs using in these fields.

At PCBONLINE, the four-terminal sensing to fine-pitch PCBAs has the testing accurateness of ±0.1mΩ and inspects 2,000 to 32,000 test points per time. All PCB assembly houses would appreciate it if their clients provide test points for the signals associated with the fine-pitch components.

Benefits of Fine-Pitch PCB Assembly

PCBONLINE fine pitch assembly for medical

Fine-pitch PCB assembly saves the PCB space dramatically, and this allows the PCB to carry more components. Products will have more functions and higher performances.

Fine-pitch components such as FBGAs package more circuits than the normal TSOP (thin small outline package) in the same size.

Fine-pitch PCB assemblies also have better thermal dissipation, because solder balls of the fine-pitch components have more contact areas with the PCB than the normal component pins do.

Conclusion

This article introduces what fine-pitch PCB assembly is, fine-pitch components, SMT stencil tips for fine-pitch assembly, and the benefits of fine-pitch PCB assembly. It also tells you to ask about the fine-pitch PCB assembly capabilities before you decide to hire a PCB assembly house. If you want reliable and cost-effective fine-pitch PCB assembly services, PCBONLINE is recommended to consider.