The links to previous discussions are at the foot of this article. In Part 2 reference was made to six chips plus memory and how small scales integration in mobile phones was evolving, and even more quickly from year 2000 onwards. Today, we rarely see the term small scale integration used as it is all about interconnection (e.g. high density interconnection (HDI) etc) and embedded ICs. Moreover, such advancements have not been limited to working with 'um' sizes but also envolving from 2D packaging to 3D packaging.
Looking at the changes mentioned in Part 2 and the presentation by National Semiconductors illustrated six chips as separate entities. An important step forward with Fine Line Interconnection and embedded ICs was shown in year 2000 arising from a GE development called 'Embedded Chip Build-Up' (ECBU). Using materials from 1998 GE demonstrated ECBU's capability could bring scale and reformation to 'packaging' chips and enhance integrated technology for PCB manufacturing. Why is this relevant? GE's development shows how six chips are capable of inclusion in an embebbed module:
Peeling back the cover, six chips in an assembly can be revealed:
This type of GE assembly is not the only 'package'. Another notable one, below, is Freescale's Redistribution Chip Package (RCP) radio-in-a-package (2006) using four chips in an assembly with an embedded module.
So from the original six separate chips illustrated in Part 2 we see how manufacturing development, scale, and integration have migrated to chips-in-a-chip packaging. Of course, as examiners, and for the purposes of forensic discovery, how are we to approach examination of PCBs and chips used in the latest smartphone's such as iPhone, Samsung, Nokia, Android, SonyEricsson etc?
As a start a useful guide to chip usage can be found at hardware evaluation websites, such as UBM TechInsights. The latter produce a useful overview of component identification following a mobile phone 'teardown'.
Germane and relevant to this discussion primer is which of the iPhone chips shown in the above images are single chips and which are embedded modules containing more than one chip? If we do not understand what is inside an embedded chip how do we know whether we are missing where memory may reside?
When the term memory is referred to it does not mean memory solely relevant to data that an examiner may extract and harvest, such as 'text messages', 'phonebook' or 'internet links' etc. Mobile forensics requires and in numerous instances demands that the examiner not only know software/data memory locations but equally hardware memory locations, too.
Links
Mobile Examination HW / SW Considerations Pt1 - http://www.trewmte.blogspot.co.uk/2012/10/mobile-examination-hw-sw-considerations.html
Mobile Examination HW / SW Considerations Pt2 - http://trewmte.blogspot.co.uk/2012/10/mobile-examination-hw-sw-considerations_15.html
GE - http://www.ge.com
Freescale - http://www.freescale.com/
UBM TechInsight - http://www.teardown.com/
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