Low-cost, wafer level underfilling and reliability testing of flip chip devices

Author(s):  
A. Grieve ◽  
M.A. Capote ◽  
H.A. Lenos ◽  
A. Soriano
2016 ◽  
Vol 2016 (S1) ◽  
pp. S1-S46
Author(s):  
Ron Huemoeller

Over the past few years, there has been a significant shift from PCs and notebooks to smartphones and tablets as drivers of advanced packaging innovation. In fact, the overall packaging industry is doing quite well today as a result, with solid growth expected to create a market value in excess of $30B USD by 2020. This is largely due to the technology innovation in the semiconductor industry continuing to march forward at an incredible pace, with silicon advancements in new node technologies continuing on one end of the spectrum and innovative packaging solutions coming forward on the other in a complementary fashion. The pace of innovation has quickened as has the investments required to bring such technologies to production. At the packaging level, the investments required to support the advancements in silicon miniaturization and heterogeneous integration have now reached well beyond $500M USD per year. Why has the investment to support technology innovation in the packaging community grown so much? One needs to look no further than the complexity of the most advanced package technologies being used today and coming into production over the next year. Advanced packaging technologies have increased in complexity over the years, transitioning from single to multi-die packaging, enabled by 3-dimensional integration, system-in-package (SiP), wafer-level packaging (WLP), 2.5D/3D technologies and creative approached to embedding die. These new innovative packaging technologies enable more functionality and offer higher levels of integration within the same package footprint, or even more so, in an intensely reduced footprint. In an industry segment that has grown accustomed to a multitude of package options, technology consolidation seems evident, producing “The Big Five” advanced packaging platforms. These include low-cost flip chip, wafer-level chip-scale package (WLCSP), microelectromechanical systems (MEMS), laminate-based advanced system-in-package (SiP) and wafer-based advanced SiP designs. This presentation will address ‘The Big Five’ packaging platforms and how they are adding value to the Semiconductor Industry.


2010 ◽  
Vol 2010 (1) ◽  
pp. 000548-000553
Author(s):  
Zhaozhi Li ◽  
Brian J. Lewis ◽  
Paul N. Houston ◽  
Daniel F. Baldwin ◽  
Eugene A. Stout ◽  
...  

Three Dimensional (3D) Packaging has become an industry obsession as the market demand continues to grow toward higher packaging densities and smaller form factor. In the meanwhile, the 3D die-to-wafer (D2W) packaging structure is gaining popularity due to its high manufacturing throughput and low cost per package. In this paper, the development of the assembly process for a 3D die-to-wafer packaging technology, that leverages the wafer level assembly technique and flip chip process, is introduced. Research efforts were focused on the high-density flip chip wafer level assembly techniques, as well as the challenges, innovations and solutions associated with this type of 3D packaging technology. Processing challenges and innovations addressed include flip chip fluxing methods for very fine-pitch and small bump sizes; wafer level flip chip assembly program creation and yield improvements; and set up of the Pb-free reflow profile for the assembled wafer. 100% yield was achieved on the test vehicle wafer that has totally 1,876 flip chip dies assembled on it. This work has demonstrated that the flip chip 3D die-to-wafer packaging architecture can be processed with robust yield and high manufacturing throughput, and thus to be a cost effective, rapid time to market alternative to emerging 3D wafer level integration methodologies.


2015 ◽  
Vol 2015 (DPC) ◽  
pp. 000248-000271 ◽  
Author(s):  
Qun Wan

The QFN package dominates IC industry with a small number of IOs due to its simplicity, maturity and low cost in mass production. However, as the industry progresses toward portability and smaller size, thinner and more compact packages such as Fan Out Wafer Level Package (FOWLP) is a better option/solution than QFN package. Due to its flip chip configuration, imbedded redistribution (RDL) interconnection and elimination of die attach layer, the FOWLP package has potential to surpass QFN package in thermal performance. This paper utilized a typical 3-stage RF power amplifier die as a thermal test vehicle, packaged with FOWLP and QFN, built FEA (Finite Element Analysis) thermal models and analyzed the thermal performance by thermal resistance breakdown and thermal bottleneck identification. Comparison of FOWLP and QFN shows that the heat paths and bottlenecks within each package are quite different. In QFN package, bottleneck lies in the die attach layer while in FOWLP package, it lies in the backend layers on the die and the RDL vias. FOWLP package may also require better thermal vias performance in PCB due to smaller footprint of LGA/Solder. Large horizontal heat spreading in a poorly design PCB may offset the thermal advantages in FOWLP package. The simulation results of both packages have good correlation with Infrared (IR) measurement of corresponding thermal test vehicles.


2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001095-001119
Author(s):  
Gillot Charlotte ◽  
Jean-Louis Pornin ◽  
Christophe Billard ◽  
Emannuelle Lagoute ◽  
Mihel Pellat ◽  
...  

Thin Film packaging (TFP) is now well known at CEA/LETI and mainly used as a protection for MEMS against degradation which can occur during back end processes: TFP is strong enough to endure the mechanical constraints due to grinding, handling and protects the device from water during the sawing step. Our TFP process is also compatible with under bump metallisation, balling and flip chip processes. The main advantages of our TFP is a very low lost of silicon area, a low cost process with 3 mask levels, and is performed on equipments commonly used in IC fab. In this paper we will speek about process improvement for a TFP overmolded. The thermo-mechanical constraints due to the standard overmolding step (100 bars and 200°C) are much more challenging for TFP: the cavity is about 5 μm high, the cap layer 2μm thick and the polymer plugging layer 6μm thick. So TFP needs to be reinforced to withstand these high constraints. Two processes using conventional IC manufacturing technologies have been developed at wafer level with two materials. 200μm and 500μm wide cavities with TFP were reinforced with these processes and first tested under pneumatically pressure at room temperature: in case of contact between the cap and the substrate, a short circuit is measured between one electrode on the substrate and another electrode behind the cap. Then, the same devices were overmolded at 75 bars and 100 bars at 185°C. In the same run, BAW resonators with TFP and one type of reinforcement were overmolded at 100 bars. The electrical performances of these resonators after overmolding fit very well to the modelling of the test card and are very good. This Compatibility between TFP and overmolding constraints could be a cost effective solution in MEMS packaging.


2010 ◽  
Vol 2010 (1) ◽  
pp. 000197-000203 ◽  
Author(s):  
Eric Ouyang ◽  
MyoungSu Chae ◽  
Seng Guan Chow ◽  
Roger Emigh ◽  
Mukul Joshi ◽  
...  

In this paper, a novel flip chip interconnect structure called Bond-On-Lead (BOL) and its ability to reduce stress in the sensitive sub-surface ELK (Extra Low K) layers of the die is presented. BOL is a new low cost flip chip packaging solution which was developed by STATSChipPAC to dramatically reduce the cost of flip chip packaging. The BOL solution allows for efficient substrate routing by virtue of the use of narrow BOL pads and the removal of solder mask in the area of the BOL pads, which eliminates the limitations associated with solder mask opening sizes and positional tolerances. In addition to the compelling cost benefits, modeling results are confirmed with empirical reliability testing data to show that BOL is superior to the traditional Bond-on-Capture Pad (BOC) configuration from a mechanical stress and reliability perspective. The focus of this paper is on the theoretical analysis of the stress, strain, and warpage associated with the BOL configuration compared with the traditional BOC structure. For the package deformation, the global finite element method is used to simulate the package warpage. For the local bumping reliability, the focus is on the ELK layers which are the critical locations affecting the package's reliability. The local finite element simulation is conducted to compare the critical ELK layers stresses with BOL structure vs. with traditional BOC structure.


2010 ◽  
Vol 2010 (DPC) ◽  
pp. 000708-000735 ◽  
Author(s):  
Zhaozhi Li ◽  
John L. Evans ◽  
Paul N. Houston ◽  
Brian J. Lewis ◽  
Daniel F. Baldwin ◽  
...  

The industry has witnessed the adoption of flip chip for its low cost, small form factor, high performance and great I/O flexibility. As the Three Dimensional (3D) packaging technology moves to the forefront, the flip chip to wafer integration, which is also a silicon to silicon assembly, is gaining more and more popularity. Most flip chip packages require underfill to overcome the CTE mismatch between the die and substrate. Although the flip chip to wafer assembly is a silicon to silicon integration, the underfill is necessary to overcome the Z-axis thermal expansion as well as the mechanical impact stresses that occur during shipping and handling. No flow underfill is of special interest for the wafer level flip chip assembly as it can dramatically reduce the process time as well as bring down the average package cost since there is a reduction in the number of process steps and the dispenser and cure oven that would be necessary for the standard capillary underfill process. Chip floating and underfill outgassing are the most problematic issues that are associated with no flow underfill applications. The chip floating is normally associated with the size/thickness of the die and volume of the underfill dispensed. The outgassing of the no flow underfill is often induced by the reflow profile used to form the solder joint. In this paper, both issues will be addressed. A very thin, fine pitch flip chip and 2x2 Wafer Level CSP tiles are used to mimic the assembly process at the wafer level. A chip floating model will be developed in this application to understand the chip floating mechanism and define the optimal no flow underfill volume needed for the process. Different reflow profiles will be studied to reduce the underfill voiding as well as improve the processing yield. The no flow assembly process developed in this paper will help the industry understand better the chip floating and voiding issues regarding the no flow underfill applications. A stable, high yield, fine pitch flip chip no flow underfill assembly process that will be developed will be a very promising wafer level assembly technique in terms of reducing the assembly cost and improving the throughput.


Author(s):  
John Hunt

Many mobile applications strive for the thinnest package possible, and therefore benefit from the high density of basic Fan Out technology. At the same time, Fan Out has evolved from a simple, single die packaging solution into a high-density solution enabling more complex 2D and 3D connectivity. Fan Out first went into volume manufacturing in 2009 with a simple, single die package using eWLB. For the next few years, it was only thought of in this context. Then in 2016, two packages came into production that broke this stereotype. The first was a hybrid, very high-density Fan Out combined with a BGA package called FOCoS for server applications. The second was a 3D PoP structure for mobile cellular phone applications called InFO. With these structures, Fan Out became a more versatile tool, capable of wider applicability. And since then, multiple manufacturers have continued the evolution of Fan Out's capabilities into more and more packaging opportunities. This presentation will illustrate how the integration of a wide variety of packaging technologies, wafer level processing, substrate evolution and Flip Chip packaging have all come together into both simple and complex packages structures. We will further explore the higher levels of integration and sophistication available using Fan Out as a basic manufacturing technology, describing the evolving functionality and complexity achieved by combining low cost materials and innovative process flows. By using such combinations of tools and processes, the resulting packages are only limited by our imagination and creativity.


Author(s):  
Lewis(In Soo) Kang

The market of Connectivity, Internet of Things (IoT), Wearable and Smart industrial applications leads Fan Out Wafer Level Package (FOWLP) technologies to a promising solution to overcome the limitation of conventional wafer level package, flip chip package and wire bonding package in terms of the solution of low cost, high performance and smaller form factor packaging. Moreover, FOWLP technology can be extended to system-in-package (SiP) area, such as multi chip 2D package and 3D stack package types. nepes Corporation has developed several advanced package platforms such as single, multi dies and 2D, 3D packaging by using FOWLP and embedding technologies. To fulfill SiP (system-in-package) with FOWLP, several dies and components have been embedded into one package which offers 40~90 % of volumetric shrink compared to the current module system with the flexibility of product design for end users. 3D package technology of PoP (Package on Package) structure will be introduced for communication module and system control application.


2010 ◽  
Vol 7 (3) ◽  
pp. 146-151 ◽  
Author(s):  
Zhaozhi Li ◽  
Sangil Lee ◽  
Brian J. Lewis ◽  
Paul N. Houston ◽  
Daniel F. Baldwin ◽  
...  

The industry has witnessed the adoption of the flip chip for its low cost, small form factor, high performance, and great I/O flexibility. As three-dimensional (3D) packaging technology moves to the forefront, the flip chip to wafer integration, which is also a silicon-to-silicon assembly, is gaining more and more popularity. No flow underfill is of special interest for the wafer level flip chip assembly, as it can dramatically reduce the process time and the cost per package, due to the reduction in the number of process steps as well as the dispenser and cure oven that would otherwise be necessary for the standard capillary underfill process. This paper introduces the development of a no flow underfill process for a sub-100 micron pitch flip chip to CSP wafer level assembly. Challenges addressed include the no flow underfill reflow profile study, underfill dispense amount study, chip floating control, underfill voiding reduction, and yield improvement. Also, different no flow underfill candidates were investigated to determine the best performing processing material.


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