BGA Packaging Technology and Traditional SMT/SMD

Posted on 2024/07/26 by PCBX 273

Compared to THT, SMT offers better miniaturization and weight reduction in any electronic application. With the use of BGA packages, high-assembly density, reliability, and improved performance are achieved; on the other hand, this requires a rework and inspection that is not really common. PCBX specializes in the area of advanced SMT and BGA assembly to help drive modern requirements of compact electronic devices.

The surface mount technology is generally viewed as directly opposite to its traditional through-hole technology because, in relative comparison to THT assembly, the space is reduced by 60% to 70% and the weight by 70% to 80% since the electronic components are soldered directly on both sides of the PCB without drilling any holes. These, together, make SMT have a critical impact on miniaturization, lightness, and thinness in electronic products. In particular, for applications with fine-pitch SMT where the pitch is less than 0.65 mm, appliances such as cell phones, PCs, and video cameras show the trend.

SMDs come in various packages: SOP (Small Outline Package), LCC (Leadless Chip Carrier), PLCC (Plastic Leadless Chip Carrier), SOJ (Small Outline J-Lead) package, SOIC (Small Outline Integrated Circuit), QFP (Quad Flat Package), etc., of which QFP is the most commonly used. In a PLCC (Plastic Leaded Chip Carrier), there are either no leads from the device at all or very small leads coming from the package.

BGA Packaging Technology - PCBX

With constant aggressive innovations in IC, more functions with more I/O pins are demanded. Electronic products also have to be as dense as they can be. Conventional SMT packaging technologies, such as QFP, make it difficult for traditional technologies to meet these demands explicitly because of their inherent characteristics as the linearly distributed leads of QFP and the limit of pitch reduction of leads.

BGA packaging technology can provide a better solution. When there are a lot of I/O pins, it's difficult to maintain expanded functionality while also lowering product volume, eventually providing a symmetric solution. The BGA packages give way to the most technical breakthroughs in application and manufacturing.

• Comparing BGA Packaging Technology to Traditional SMT/SMD Packaging

Comparison of BGA packaging technology is also always provided with some views on traditional SMT/SMD packaging. Among them, the most important is lead structure.

Items	Gull wing	J lead	I lead	BGA
Capability to adapt multi-lead package	Good	Ordinary	Ordinary	Excellent
Package thickness	Good	Ordinary	Ordinary	Excellent
Lead rigidity	Ordinary	Good	Ordinary	Excellent
Capability to adapt multi-soldering	Excellent	Ordinary	Ordinary	Ordinary
Self-alignment capability in reflow soldering	Good	Ordinary	Ordinary	Excellent
Capability to be inspected after soldering	Ordinary	Good	Ordinary	Ordinary
Cleaning difficulty	Ordinary	Good	Excellent	Ordinary
Effective area utilization	Ordinary	Good	Ordinary	Excellent

• Comparison of Package Size

Three types of packages are used as comparison examples with their parameters displayed in Table 2 below.

Package	Lead Count	Pitch(mm)	Package Size(mm)
BGA	625	1.27	32*32
TAB	608	0.25	44*49
PQFP	304	0.5	46*46

Based on the parameter comparison in the above table, it’s obvious that BGA features the largest number of leads and the smallest package size.

• Assembly Density Comparison between All Types of Package Structures

Assembly density comparison between all types of package structures is summarized in Table 3 below.

Package	Pitch (mm)	Size (mm)	I/O Pin Count
BGA	1.27	32.5*32.5	625
FPD	0.5	32.5*32.5	240
UFPD	0.4	32.5*32.5	296
UFPD	0.3	32.5*32.5	408
TCP	0.25	32.5*32.5	480
TCP	0.2	32.5*32.5	600

• Assembly Procedure

BGA (Ball Grid Array) package technology is an advanced version of the traditional SMT (Surface Mount Technology) packages, which explains the intrinsic advantages of SMT. Both the fine pitch components and BGA package components are assembled using a similar assembly procedure, which is indicated in the figure adjacent below.

Assembly Procedure - pcbx

• Assembly Defect Rate

BGA packages often have a lower defect rate and are more manufacturable than QFP peripherals.

• Final Inspection

Inspecting fine-pitch QFPs needs additional resources because reliability tests are necessary. Typically, an automated system is required for testing QFP short circuits or open circuits, which increases the cost of manufacturing them. The converse is true for BGA packages, which have a high manufacturing efficiency and a low defect rate. As a result, BGA inspections focus primarily on alignment and placement.

• Rework

Reballing BGA packages is generally more expensive than reworking QFP components for two reasons:

a. Because of the design, rewiring a single short or open circuit in a BGA is nearly impossible; hence, defect-free assembly is uncommon.

b. QFP rework is easier than BGA package rework. Frequently, reworking a BGA package necessitates the use of specialized equipment, which increases the cost.

c. BGA variations do not ensure post-rework functionality; however, some QFP components can be reused if thoroughly dismantled.

The basic comparison between BGA rework and typical SMT rework methods reveals that BGA rework requires full preheating. While the temperatures used for preheating BGA components are likewise used by other SMDs, they have a different temperature ramp rate or transit time between respective heating temperature points. Besides, the heating process for BGA components should be a gradual one if the preheating curve is smooth.

Second, all solder balls in the BGA must be heated simultaneously. Solder paste is precisely applied, and the solder junctions cannot be modified. BGA components have a large pitch, which makes depositing easier.

• Soldering Positions to Be Kept Reserved

The major difference between BGA and QFP in terms of reserved soldering position comes from their respective hidden array and lead configurations. Each enjoys a variety of benefits related to enhancing PCB design with superior trace density, tracing activity, and general performance.

Good heat dissipation properties of the BGA packages make them exhibit the best conditions even though the confinement in the PCB design rules demands narrow spacing between thermal parts.

• Solder Joint Reliability

The following are some of the factors that have a significant impact on board and assembly rates of solder joints: board solderability, component soldering performance, component coplanarity, and solder paste volume. The ultimate product's quality would be the result of these aspects being combined.

QFP is one of the traditional microelectronic packaging technologies. Technically speaking, it is already going to give way to one modern packaging technology as far as new expectations: the feature sets and I/O pin counts.

PCBX Specializes in BGA and other types of SMD Assembly

With over two decades of industry expertise, PCBX has successfully assembled electrical components of various packaging types, including BGA, QFN, QFP, CSP, WLCSP, and so on. We can construct SMDs in the PCBX workshop starting with 01005, with a minimum pitch of 0.4mm for BGA and 0.35mm for WLCSP. It is consistent with the current trend of miniaturizing electronics.

With our Advanced PCB Assembly services, we can offer many more, so do not hesitate to get in touch. Quotations are free and always welcome.