Further information about the different categories of IC packages can be found below:. The foremost example in this regard is the BGA package, which comes in various formats, including the tiny chip scale packages — sometimes referred to as QFN packages — and larger packages.
BGA construction involves an organic substrate, and its best application is in multichip structures. Multichip modules and packages are the leading alternatives to solutions that use a system-on-chip format. Other options include the two-stepped and double-surface interconnection packages. Additionally, a category for wafer IC assembly, known as wafer-level packaging WLP , has caught on in industry parlance.
Choosing the right IC package for your applications starts with knowing technical information about the wide range of design considerations that go into producing IC packages.
Many companies also consider using laminates as alternatives to lead frames and select substrates that work well with metal conductors. The performance of an IC package relies largely on its chemical, electrical and material makeup. Despite their functional differences, lead-frame and laminate packages both rely heavily on material composition. Lead-frame packages, the prevailing format, use silver or gold wire-bond finishes , attached with a spot-plating method.
That makes the process simpler and more affordable. On ceramic packages, Alloy 42 is a widely used metal type because it works with the underlying material. On plastic packages, the copper lead frame is preferable because it safeguards the solder joint and offers conductivity.
Due to policies in certain territories, the material is also one of the critical factors on surface mount plastic packages. Because of revisions in European standards, the lead finish has been a matter of intense scrutiny on next-level packaging assembly. The aim has been to find viable replacements for tin-lead solders, which are easily applied and have been a longtime staple throughout the industry. However, manufacturers have yet to unify around a single solution, due in part to the widespread competition among suppliers.
The lead issue is unlikely to resolve itself for some time to come. Starting in the late s, laminates emerged as an alternative to lead frames in chip-to-board assemblies.
Today, laminates are widespread throughout the IC packaging solutions industry, due to their relative cost-effectiveness when compared to ceramic substrates. The most popular laminates are the organic, high-temperature types, which provide superior electrical characteristics and are also more affordable. Amid the rise in popularity of semiconductor packages, there has also been an increased demand for applicable substrates and interposers.
A substrate is the part of an IC package that gives the board its mechanical strength and allows it to connect with external devices. The interposer enables connective routing in the package. Package substrates come in rigid and tape varieties. Rigid substrates are firm and defined in their shape, whereas tape substrates are slim and flexible. In the early days of IC manufacturing, substrates consisted of ceramic material. Today, most substrates are made of organic material.
If a substrate consists of multiple thin layers stacked to form a rigid substrate, it is known as a laminate substrate. The former consists of epoxy, while the latter is a high-grade resin material. Due in part to its insulation qualities and low dielectric constant, BT resin has emerged in the IC industry as one of the favored laminate materials.
BT has also become the favored resin for chip scale package CSP laminates. Meanwhile, competitors around the globe are manufacturing new epoxy and epoxy-blend alternatives, which threaten to give BT a run for its money, possibly reducing prices overall as the market becomes more competitive in the years ahead.
As an alternative to rigid substrates, tape substrates are mostly made of polyimide and other types of temperature-tolerant, durable materials.
The advantage of tape substrates is their ability to simultaneously move and carry circuits, which makes tape substrates the preferred choice in disk drives and other devices that carry circuits amid fast, constant movement. The other main advantage of tape substrates is their low weight, which means they do not add even the slightest dimension of heaviness to an applied surface.
IC packages must also come with metal conductors that can route signals to various interconnecting features. Therefore, it is essential for substrates to help facilitate this process. Substrates route the input and output signals of a chip to other features on a system in packages. The placement of foil, typically copper, that is bonded to the laminates in the substrate achieves the metal conductivity. Immersion layers of gold and nickel often get applied as finishes over the copper to prevent interdiffusion and oxidation.
Lead frames are the most common IC packages. You would use these packages for wire-bond interconnected dies, with a silver or gold-plated finish. For surface-mount plastic packages, manufacturers often use copper lead-frame materials. Copper is highly conductive and extremely compliant, so it can be beneficial for this purpose. Many manufacturers are trying to move away from actual lead finish lead-frame IC packages, but they have been in such frequent use for so long that it is a difficult transition for some.
The most common packages include the following:. Substrate packages, such as ceramic-based packages, will require an alloy that is similar in coefficient of thermal expansion CTE to ceramic, like Iconel or Alloy In the die attachment process, we bond the die to the substrate with special die-attach materials, which we can use in face-up wire-bond assembly.
Good die-attach material is electrically and thermally conductive, making it ideal for substrate packages. Laminate packages are an excellent low-cost alternative to ceramic substrates and have a lower dielectric constant as well. Media New media New comments Search media. Blogs New entries New comments Blog list Search blogs. Groups Search groups. Log in Register. Search only containers. Search titles only. Search Advanced search….
New posts. Search forums. Log in. Install the app. Contact us. Close Menu. Welcome to EDAboard. To participate you need to register. Registration is free. Click here to register now. Register Log in. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. They do build on some previous knowledge, though, so if you aren't familiar with these topics, consider reading their tutorials first When we think integrated circuits, little black chips are what come to mind.
But what's inside that black box? The guts of an integrated circuit, visible after removing the top. The real "meat" to an IC is a complex layering of semiconductor wafers, copper, and other materials, which interconnect to form transistors, resistors or other components in a circuit.
The cut and formed combination of these wafers is called a die. While the IC itself is tiny, the wafers of semiconductor and layers of copper it consists of are incredibly thin. The connections between the layers are very intricate.
Here's a zoomed in section of the die above:. An IC die is the circuit in its smallest possible form, too small to solder or connect to. To make our job of connecting to the IC easier, we package the die. The IC package turns the delicate, tiny die, into the black chip we're all familiar with. The package is what encapsulates the integrated circuit die and splays it out into a device we can more easily connect to.
Each outer connection on the die is connected via a tiny piece of gold wire to a pad or pin on the package. Pins are the silver, extruding terminals on an IC, which go on to connect to other parts of a circuit. These are of utmost importance to us, because they're what will go on to connect to the rest of the components and wires in a circuit. All ICs are polarized , and every pin is unique in terms of both location and function.
This means the package has to have some way to convey which pin is which. Most ICs will use either a notch or a dot to indicate which pin is the first pin. Sometimes both, sometimes one or the other. Once you know where the first pin is, the remaining pin numbers increase sequentially as you move counter-clockwise around the chip. One of the main distinguishing package type characteristics is the way they mount to a circuit board. Through-hole packages are generally bigger, and much easier to work with.
They're designed to be stuck through one side of a board and soldered to the other side. Surface-mount packages range in size from small to minuscule. They are all designed to sit on one side of a circuit board and be soldered to the surface. The pins of a SMD package either extrude out the side, perpendicular to the chip, or are sometimes arranged in a matrix on the bottom of the chip. ICs in this form factor are not very "hand-assembly-friendly.
DIP, short for dual in-line package, is the most common through-hole IC package you'll encounter. These little chips have two parallel rows of pins extending perpendicularly out of a rectangular, black, plastic housing. The overall dimensions of a DIP package depend on its pin count, which may be anywhere from four to The area between each row of pins is perfectly spaced to allow DIP ICs to straddle the center area of a breadboard.
This provides each of the pins its own row in the board, and it makes sure they don't short to each other. They're inserted into one side of the board and soldered into place on the other side. Sometimes, instead of soldering directly to the IC, it's a good idea to socket the chip. Using sockets allows for a DIP IC to be removed and swapped out, if it happens to "let its blue smoke out.
There is a huge variety of surface-mount package types these days. In order to work with surface-mount packaged ICs, you usually need a custom printed circuit board PCB made for them, which has a matching pattern of copper on which they're soldered. Here are a few of the more common SMD package types out there, ranging in hand-solderability from "doable" to "doable, but only with special tools" to "doable only with very special, usually automated tools".
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