Application Guide for IC Substrates

Integrated Circuit Substrate PCB

IC Substrate is a substrate for packaging integrated circuit (IC) chip, also known as packaging substrate or IC carrier board. It is a medium of silicon, carbon or ceramic, which is fixed to the chip as the bottom plate, and allows the chip and the chip and the circuit board to be connected by power. The IC substrate plays the role of electrical conduction, while providing the chip to provide the chip to protect, support, heat dissipation, and form a standardized installation size. The IC substrate is a key special basic material used in advanced packaging, which is mainly used in mobile smart terminals, service/storage and other fields. According to the packaging process, the nature of the material, and the field of application, the IC substrate can be classified differently.

History of IC Substrate

The IC substrate finds application during the integrated circuit encapsulation phase. As semiconductor technology ascends, the dimensions of IC substrate continue to diminish. Concomitantly, thanks to persistent enhancement in integration, related IC packages are progressing towards ultra-vast multi-pin, compact pitch, and extreme miniaturization. Global integrated circuit encapsulation technology has traversed five distinct developmental phases so far.

Presently, the predominant methodology utilized globally within the packaging sector is Phase III, grounded on CSP BGA, transitioning towards system-level packaging (SiP). Attending to Phase IV and V packaging technologies, represented by Flip-chip packaging (FC) and on-chip Bumping, advancement remains a steady course.

Refining historic 2000 as the node, the packaging industry is bifurcated into conventional and advanced packaging categories.

First Phase: Predating the 1970s (the original DIP epoch). The prevailing encapsulation technique is pin insertion (PTH), with predominant forms being CDIP, PDIP, and transistor package (T0). Due to stringent increased density and frequency impracticalities, it falls short of meeting the enhanced automation demands for production.

Second Phase: Mid-1980s (surface mount era). The transformation from pin insertion package to the surface patch package significantly enhances printed circuit board assembly density, facilitating automated production. Despite remarkable ease in production, its capabilities in terms of package density, connectivity count, and circuit frequency remain limited, posing significant challenges in catering to emerging ASIC and microprocessor development necessities.

Third Phase: The 1990s ushered in the era of area array packaging. Principal packaging formats encompass BGA, CSP, and WLP. BGA technology substantially diminishes the interconnection distance between the chip and the system, sustaining an identical pace with the chip’s ongoing evolution. CSP technology mitigates the protracted fundamental conflict pertaining to the discrepancy between the tiny chip and the large packaging, igniting a revolution within integrated circuit encapsulation technology.

Fourth Phase: By the end of the 20th century, we embarked upon the age of microelectronic packaging technology stacked stacking (MCM), evolving from the basic notion of encapsulated components into comprehensive systems. Significant packaging scenarios embody MCM, and three-dimensional types. SIP, Bumping.

Fifth Phase: Commencing from thefirst decade of the 21st century, the paradigm shifts towards system-level single-chip packaging (SoC), together with microelectromechanical system package (MEMS).

 

What is the main material of ic substrate

1) One of the main raw materials: copper foil

Similar to PCB, the copper foil required for IC carrier board is electrolytic copper foil, and it needs to be ultra-thin and uniform copper foil, with a minimum thickness of 1.5μm, generally 2-18μm, while the thickness of copper foil used for traditional PCB is about 18 or 35μm. The price of ultra-thin copper foil is higher than ordinary electrolytic copper foil, and the processing difficulty is also greater.

(2) The second major raw material: substrate sheet

Carrier plate substrate similar to the PCB copper-clad plate, mainly divided into rigid substrate, flexible film substrate and co-fired ceramic substrate three major types, of which the rigid substrate and flexible substrate has more room for development, while the development of co-fired ceramic substrate tends to slow down.

IC carrier substrate main considerations include dimensional stability, high frequency characteristics, heat resistance and thermal conductivity and other requirements:
At present, there are three main materials for rigid package substrates, namely BT materials, ABF materials and MIS materials;

Flexible package substrate substrate materials mainly include PI (polyimide) and PE (polyester) resin;

Ceramic package substrate materials are mainly alumina, aluminum nitride, silicon carbide and other ceramic materials.

 

What are the advantages of the IC substrate

 

The IC substrate has the following advantages:

1. High -density: IC substrates can achieve high -density integration, so that more circuits and functions can be implemented in smaller spaces.

2. High reliability: The IC substrate adopts advanced packaging technology, which can improve the reliability and stability of the product.

3. Good heat dissipation performance: The IC substrate can effectively transmit the heat generated by the chip, thereby improving the heat dissipation performance of the product.

4. Easy installation and maintenance: IC substrates can be installed and maintained in an automated manner, reducing production costs and labor costs.

5. Long life: IC substrates can use high -quality materials and advanced production processes, thereby extending the service life of the product.

Application Guide for IC Substrates

Application of Integrated Circuit Substrate PCB

We can use IC substrates for the following:

●Memory chip packaging

●Micro-electromechanical systems (MEMS) chip packaging

●Radiofrequency (RF) chip packages

●Processor chip packaging • Integrated circuitry in high-speed communication devices.

●These chips find in real-world applications such as smartphones, laptops, and tablets.

●Laptop computers, printers, and memory devices like RAM modules

●Telecommunications

●Industrial machinery and Automotive applications

●Networking applications in medical care, industrial control, aerospace, military, and telecommunications

 IC Substrates

 

Manufacturing Methods of IC Substrates

First and foremost, we must comprehend three separate PCB manufacturing processes. There are currently three types of PCB and IC substrate manufacturing processes: subtractive process (SP), additive process (AP), and modified semi-additive process (MSA) (MSAP).

Subtraction method (SP)
The most traditional PCB manufacturing process involves first plating a certain thickness of a copper layer on the copper-clad laminate, followed by a dry film to protect the circuit and through-hole, and finally etching the unnecessary copper sheet. This method’s crucial demerit is that the copper layer’s side etches during the etching process. Because of lateral etching, the minimum line width/spacing of PCB can only be greater than 50 m (2mil), limiting its use to ordinary PCB, FPC, and HDI PCB products.

The addition method (AP)
It involves first exposing the circuit to an insulating substrate containing a photosensitive catalyst, followed by selective chemical copper deposition on the exposed thick circuit to create a complete PCB. Because this method does not require lateral etching, it can achieve very high accuracy and fabrication times of less than 20 m; currently, this method has high substrate and process flow requirements, a high cost, and a low output; it comprises primarily produce WB or FC IC substrate, and its process can reach 12 M / 12 M.

MSAP (modified semi-additive process)
At first, the thin copper layer electroplates to laminate the copper-clad. The areas that do not need protection for the electroplating and the more chemical copper layer are removed by flash etching, leaving the required copper layer line. Because the copper layer is very thin at the start of electroplating, the flash corrosion time is very short, so side corrosion has little influence.

Compared to the subtraction and addition methods, the MSAP process has the advantages of high yield and low production cost, making it the most popular fine circuit board manufacturing method. This technology acknowledges commonly used in the production of CSP, WB, and FC IC substrates, as well as other fine-line substrate boards. Although the SLP (substrate-like PCB) is a printed circuit board, its minimum line width/line spacing from a process standpoint is 30 M / 30 m, so it produces by subtraction, and MSAP process technology is also required.

 

Manufacturing Process of IC Substrate PCB

Copper patterning and plating
The first step involves copper patterning and plating technology, which correlates to other aspects of diverse technology. Fine-line fabrication, uniform copper plating thickness, and circuit and control compensation technologies are part of the technology. The copper material prepares by manipulating and shaping it. As a result, this technique necessitates the use of machinery that adjusts the thickness and shape of the copper. As a result, it is the first step in the manufacturing process.

Solder mask
The second process is the solder mask, which consists of an IC substrate solder mask with solder mask printing and hole-filling technologies. Remember that the height difference between the pad and the solder mask on the substrate should be less than 15mm (ideal – 10mm and below). This helps in accomplished by applying a solder mask to the substrate. The substrate manufacturer will employ a combination of solder mask printing technology and through-hole filling equipment.

Surface treatment
This procedure entails buffing and polishing the substrate to ensure a uniform and even surface. It consists of using ENIG and ENEPIG surface finishes (the most common) to achieve a uniform thickness in the surface finish.

Reliability and inspection tests
Finally, design engineers test IC substrates for reliability and inspect their quality using specialised modern equipment. However, the process differs from that used in standard PCBs. The manufacturing company must test the last substrate for reliability and integrity during this process.

 

IC substrates play an indispensable role between the PCB and the IC chip within the realm of electronics engineering. Given their vital function, mastering every aspect of these will significantly enhance the success rate of your designed IC solution. Consequently, kindly incorporate the aforementioned factors when formulating your IC design for optimal results.

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