Page 68 Continued from page 63
finished devices may range from level 3 to the best solutions meeting level 1 requirements. For high-tem-
www.us-tech.com Recent Advances in Die Attach Film
perature applications typically beyond +125 to +150°C, newer non- epoxy-based DDAF materials can withstand long-term use at +200°C
and higher. Traditional flip-chip packaging
employs wire-bonding and solder- bump reflow for most requirements. Growing needs for higher speed, improved performance, and lower costs continue to drive semiconductor
oelectronics/05-Alien.pdf.). It should be noted that these low-cost RFID devices are limited to operating tem- peratures of less than +60°C and they do not provide stable operation in high-moisture environments. That contact resistance can be
July, 2014
The illustrations show the steps of a typical manufacturing process with wafer-level packaging and how devices are integrated using dicing tape and die-attach films that are directly laminated on the wafer before dicing.
packaging towards shorter paths of interconnections between each level of a stacked-chip package.
Drive for Lower Costs The drive for lower packaging
costs has led to many innovative packaging solutions. The lowest-cost electronic devices, such as UHF radio- frequency- ident i f icat ion (RFID) tags, have been produced suc- cessfully in large volumes using direct flip-chip mechanical compres- sion contact. (More on this on RFID manufacturing from Alien Tech - nology is available from NIST at:
http://usms.nist.gov/workshops/macr
properly maintained for long-term use within specified temperature and environmental constraints provides hope that solutions for high-perform- ance applications can be achieved with more engineered materials and packaging. For successful flip-chip packaging, the flip-chip underfill must also perform as a stable die bonding adhesive. For this to hap- pen, a number of characteristics are required:
easily placed either on the substrate or on the interconnection front side of the chip. DDAF will still be appli- cable. If paste underfill adhesive is to be useful, it must stay in place after being dispensed onto the sub-
l The underfill adhesive must be
strate or chip. l
when forming interconnections. l
The underfill adhesive must not prevent contact when the chip and package substrate interconnections are lined and compressed for bond- ing. Unlike the use of Z-axis, uniaxi- al, conductive adhesive, any particu- late matter could prove detrimental
well above +150°C. l
have a high glass transition temper- ature (Tg) and modulus to maintain good electrical contact and charac- teristics. For commercial and mili- tary applications, the Tg should be
as low in coefficient of thermal expansion (CTE) as the CTE of higher filled traditional epoxy
to +250°C in less than 10 seconds. l
For acceptable productivity, the un - derfill adhesive should cure at +175
underfills (<30 ppm/°C). l
To meet the JEDEC/ IPC Level 1 moisture sensitivity requirements, the moisture absorption should be well below 0.5 percent in saturation.
There are now non-epoxy-based,
high temperature, underfill-adhesives in paste or film format in thickness of 25 to 75µm for such applications.
Continued on next page See at SEMICON West, Booth 1225 The underfill adhesive should be Flip-chip underfill adhesive should
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96