Embedded passive component

Embedded passive component Embedded passive component (Formed type) (Inserted type)... 

As explained above, in LTCCs that incorporate a variety of materials with embedded passive components, especially where fine wiring is used, it will be beneficial to develop LTCCs that use mainly silver. However, in circuit board applications consisting of conductor and insulating materials with fine... 

A surface-mounted LTCC RF band-pass filter (bottom half of Figure 1.11) operates at 942 MHz and, by embedding inductors and capacitors in the 17-layer structure, replaces 9 individual passive components (top half of Figure 1.11). Some layers in the stackup are 50 pm (2 mil) thick for use as the capacitor dielectrics. This filter was designed for cellular phone applications and significantly reduced board space over its discrete equivalent. In addition, assembly time was reduced and, with fewer solder joints for this function, reliability was improved. 

This module (Figure 1.24) is an antenna switch/filter module designed for dual-band portable wireless telephones. It combines GSM/DCS/PCS diplex-ing and receiving/transmitting antenna functions. The 8.9 x 9.9 mm (0.35 x 0.39 in.) LTCC module uses a 26-pad EGA format. In addition to the surface-mounted passive components, the six-conductor-layer structure incorporates 13 embedded capacitors and inductors to form the diplexer and 2 low-pass filters. 

Passive integration is an effective technique to increase the component density. It is defined as a combination of circuit carrier (substrate, board, and interconnections) with passive components like resistors, capacitors, inductors, and line elements in one technology. Passive elements may be integrated on the surface or embedded in a multilayer structure of the substrate. The goal is to achieve ... 

In Reference 1, it is stated that the ratio between passive and active components is about 9 1 for a mobile phone. Furtirermore, the passives occupy 80% of the space and account for 70% of the cost. Three hxmdred components is tire average passive component count in cellular phones. Road maps for these applications show a clear trend toward higher integration on tire chip side. From six ICs necessary for the phone fimction in 1998, it decreased to one for the third generation of cell phones in 2004 [2]. According to a study by Prismark [3], the need for the embedded component density will grow to about 30 passives/cm in the year 2010. 

Prismark Partners LLC, Pushing the Shrinking Envelope — A Status Report on Embedded Passives in PCBs, Cold Spring Harbor, NY, December 2000. Thust, H., Thelemarm, T., Ehrhardt W, Driie, K.-H, Muller, J., Embedded components and functions in LTCC - review and prospect. Proceedings of Ceramic Interconnect Technology The Next Generation, Denver, CO, April 2003, invited paper. 

The trend in surface-mount technology is to use smaller passive devices such as capacitors, resistors, and inductors. Also, there is the use of embedded passive devices, that is, resistors and capacitors that are located within the circuit board laminate. Embedded passive devices free up additional surface area for larger, active components. 

Various new processes have been developed to build functional elements and devices on the flexible substrates. They have been generating more functions than wiring or assembling board of the discrete components. They are the similar ideas as embedded passive technologies of multilayer boards, but they generate more values with flexible substrates. Table 66.2 shows several material examples and applications. 

Figure 1.6 Passive components embedded in substrates [LTCC (a), and printed resin board (b)].

The stratum comeum is usefully thought of as a brick wall , with the fully differentiated comeocytes comprising the bricks , embedded in the mortar created by the intercellular lipids. A layer of lipid covalently bound to the comified envelope of the comeocyte contributes to this exquisite organization. The intercellular lipids of the stratum comeum include no phosphohpids, comprising an approximately equimolar mixture of ceramides, cholesterol and free fatty acids. These non-polar and somewhat rigid components of the stratum comeum s cement play a critical role in barrier function. On average, there are about 20 cell layers in the stratum comeum, each of which is about 0.5 fim in thickness. Yet, the architecture of the membrane is such that this very thin structure limits, under normal conditions, the passive loss of water across the entire skin surface to only about 250 mL per day, a volume easily replaced in order to maintain homeostasis. 

Integration of passives in LTCC is also used to build components. Several elements can be combined in a multilayer structure to achieve a specific electrical function (e.g., a band-pass filter). These small-sized components have terminations allowing surface-moimt assembly operations (land grid, castellation, or ball grid array [BGA]). Depending on the nature of diese passive multicomponent devices, they are referred as monolithic (only LTCC elements) or hybrid [58] (mixture of embedded components and additional surface-mounted elements). Reasons for not implementing all passives in the hybrid type are ... 

Embedded components Components formed or inserted inside the primary interconnect substrate are said to be embedded. Embedded components can be either passives or actives (see the preceding definitions). 

Placed embedded components In contrast to formed components, components (both discrete passives and small actives) can also be placed inside the board using conventional placement machines and technologies. This manufactming technique integrates very well with the any layer via type of contruction. 

FIGURE 21.1 Cross section of a multilayer board showing the use of all types of embedded components, both passive and active. (Courtesy of Jisso International Council [JICJ.)... 

For passivation treatments other than for scale removal, less aggressive acid solutions are used. The purpose of these treatments is to remove any contaminants that may be on the component s surface that could prevent the formation of the oxide layer locally. The most common contaminant is embedded or free iron particles from forming or machining tools. A10% nitric add solution is effective in removing free iron. For martensitic, ferretic, and predpitation-hardening grades, a nitric acid solution inhibited with sodium dichromate is used so as not to attack the stainless steel too aggressively. 

Cap In addition to the component of soil resistance acting on piles, the passive pressure soil resistance on the vertical pile cap face can be added to the stiffness and resistance obtained from the pile members. This is contingent on stable level ground conditions. The pile cap stiffness can be estimated as the ultimate soil capacity divided by an estimated displacement to mobilize this capacity. Centrifuge tests (Gadre 1997) showed that the deflection level to reach the ultimate pile cap capacity occurs at about 0.02 times the embedment depth. This equivalent linear secant stiffness can be added to the stiffness of the piles. 

Several AM techniques have been modified to work at a small scale to deposit passive electronic structures (conductors, insulators, resistors, antennas, etc.). These techniques are often known as direct-write techniques and, for instance, use electronic inks that contain nanoparticles or other additives that result in electronic properties after drying, thermal decomposition, or other post-treatment. By combining direct-write techniques with other AM techniques it becomes possible to create multifunctional 3D-embedded electronic structures on a layer-by-laycT basis that combine structural, thermal, electronic, and other functions into a single component. 

---