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March, 2020

Scanning Acoustic Microscopy Analyzes 3D Packages in the Z-Dimension aperture of the transducer. The fre-

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single-layer views to tray scans and cross-sections. Multilayer scans can include up to 50 independent layers. Images from different depths can be combined into a single scan as well, called tomographic acoustic micro imaging (TAMI). When even higher throughput

is required, up to four transducers can simultaneously scan for higher throughput. Multiple transducers can be used on a single substrate and the images then stitched together, or multiple transducers can simultane- ously scan multiple substrates. “Scanning acoustic microscopy

provides nondestructive imaging of defects and delaminations in die and package materials,” says Lisa Logan, applications manager, scanning acoustic microscopes, PVA TePla Analytical Systems. “SAM is particularly useful for

inspection of small, complex, three- dimensional devices,” adds Logan. “The equipment is highly sensitive to the presence of delaminations and air gaps at sub-micron thicknesses.” The most common defects in 3D

packaging are delamination, cracks in substrate, die tilt, misalignment, and voids in micro-bumps, bump defects, solder bridging, popcorn cracks, voids in underfill, and voids and delamination in TSVs. The resolution of microscopic

image depends on the acoustic fre- quency, the material properties and

quency of the ultrasonic signals gen- erated for 3D package inspection is typically within 15 to 300 MHz. Transducers, the heart of all

SAM systems, play such a critical role that manufacturers like PVA TePla Analytical Systems design and manufacture the transducers used in the equipment in a proprietary thin film technology process. The frequency of the ultrasonic

signals can even be increased into GHz range, which makes it possible to detect defects even in the sub- micron range. PVA TePla’s high-res- olution, GHz-frequency SAM tool, for example, successfully detects voids in TSVz of 5 µm diameter and 50 µm depth, immediately after plating. According to Logan, several

leading suppliers of programmable logic devices have already evaluated and purchased high-resolution SAM equipment for nondestructive analy- sis of next-generation 3D products to scan for packaging anomalies. “3D chip manufacturers are try-

ing to push the limits on what they can detect, in terms of defects,” says Logan. “So, today, the evaluation of scanning acoustic microscopy equip- ment often comes down to which equipment delivers the highest reso- lution at the fastest throughput speeds for 100 percent inspection.” Contact: PVA TePla America,

Inc., 251 Corporate Terrace, Corona, CA 92879 % 951-371-2500 E-mail: Web: r

Industrial Flash Memory with Security Features

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example, require a reliable logging mechanism. Each event that must be logged is stored permanently and is unmodifiable. Hash-chains of datasets in

write once read multiple (WORM) memories ensure the detection of any tampering or deletion of data elements. Exported data is sealed, using a digital signature. It is a per- fect solution for securing fiscal applications in cash registers. Asymmetric encryption with secure elements can also be simply used for data protection. The application saves pass-

word-protected data so that it can only be read by authorized personnel or a specific system — for example, images from surveillance cameras or bodycams.

Designating an ID to “Things” If the storage medium allocates

a unique identity to applications and systems, this identity can be used in other ways as well. More and more devices are connected within the IIoT and are accessible from the internet. Remotely services systems,

such as industrial controls or IIoT gateways, become vulnerable. In the future, networked systems must be protected from misuse and “identity theft.” Data access must be restrict- ed. The neatest solutions are data encryption and clearly identifiable machine-to-machine (M2M commu- nication participants).

Similar to the protection of

online communications in IT, where users identify themselves as part of a two-factor authentication using a smartcard token, the memory mod- ules with secure elements provide the option to give M2M communica- tion participants a unique ID. This way, a “thing” knows that the data or data queries received from another “thing” are correct and that the source is truly the system component that it claims to be. Integrating smartcards on memory cards allows non-cloneable identities to be allocat- ed to the systems. These systems are then able to authenticate themselves and to send and receive cryptograph- ically secured data. The secure flash media offered

by Swissbit for these tasks are exten- sions of proven SD and microSD memory cards for industrial require- ments. These are available with extremely durable SLC flash or with the more cost-effective “durabit” MLC — a Swissbit brand that encom- passes special firmware features that prolong endurance and retention of the MLC NAND chips far beyond what is commonly feasible. The firmware also includes

many security features, such as an integrated AES encryptor, or the option to apply the WORM mode to the medium. For applications that require a unique, non-forgeable iden- tity, the memory card includes an additional smartcard as a secure ele- ment. It assumes the function of a

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