An IC substrate is used for carrying bare integrated circuits (IC) and connects the IC to the main printed circuit board (PCB). An IC probe card is used to test the IC in IC fabrication. In the PCB industry, we consider an IC substrate board and probe card as two of the most advanced PCBs.
What is an IC Substrate
To let a bare IC work and protect it from thermal, vibration, dust, moisture, and chemicals, you will have it assembled with an IC substrate and a plastic/ceramic/metal enclosure.
An IC substrate is an advanced PCB used to support the IC and connect it to the bottom PCB board electrically. Besides, it conducts thermal from the IC to the bottom PCB and protects from overheating.
With the IC substrate, the whole IC is a surface mount device (SMD) and can easily be mounted on the PCB with other SMDs. Sometimes, an IC substrate can even be embedded with passive and active components to achieve some system functions.
An IC substrate is a double-sided ultra HDI PCB. It is very thin with a line width/space of 30 microns, even as low as 10 microns.
On the top of the IC load board, the IC is bonded with it by gold wires or flip-chip. On the bottom of the load board, there are solder balls that will melt to connect the whole IC package to the PCB by reflow soldering.
You can refer to wire bonding and flip-chip bonding from the article Wire Bonding VS Flip Chip Bonding: How to Customize COB LEDs.
Types of IC Substrates
According to different substrate materials, IC substrate boards are classified into three types -- rigid, flexible, and ceramic IC substrates.
Rigid IC load boards are the most common IC substrate boards. The substrate materials for rigid IC substrates include bis maleimide triazine resin (BT resin), Ajinomoto build-up film (ABF), and molded interconnect substrate (MIS). BT IC substrates are used for FPGA (field-programmable gate array) and high-reliability network chips. ABF IC substrates are used for large high-level chips such as CPU, GPU, and chipset. MIS ICsubstrate boards are used for analog and power ICs.
Flexible IC load boards are polyimide (PI) and polyethylene (PE) based PCBs. The applications of flexible IC substrate boards are automotive, high-end consumer electronics, and military fields such as launch vehicles, cruise missiles, and space satellites.
Ceramic IC load boards are aluminum nitride (AlN), aluminum oxide (alumina), and silicon carbide (SiC) PCBs. The applications of ceramic IC substrate boards include semiconductor lighting, laser, optical communications, aerospace, automotive electronics, and deep sea drilling.
What is An IC Probe Card
On a wafer, after the photolithography process, circuits are printed and irons are added to control the conductivity. Engineers make hundreds to millions of transistors on it and pour copper for wiring. A bare IC is manufactured.
After the wafer manufacturing, it is necessary to test the IC before IC packaging.
In testing the IC, bare ICs are placed on an IC probe card to inspect the circuit conductivity and functions to ensure their quality.
As you can see, an IC probe card is critical for the IC industry.
Currently, IC probe cards take up about 10% of the PCB market value. The IC probe card has top complexity and is considered one of the most advanced PCBs.
What Functions Does An IC Probe Card Play?
After the wafer manufacturing, it is necessary to exclude the not-good wafers to prevent economic losses from packaging the not-good wafers.
The IC probe card is used to connect the test machine and the Pad on the Die during IC testing. In testing, it acts as the physical interface of the IC substrate.
Sometimes, the probe card can connect to the IC substrate through a socket or other interface circuit.
Features of IC Substrates and Probe Cards
An IC Substrate and probe card feature a thin thickness, small size, high density, and high precision.
High-density PCBs have microvias, including buried and blind vias. HDI vias are drilled by laser and copper filled through electroplating.
IC substrates and probe cards belong to HDI PCBs but are more complex. The finest pitch (center-to-center distance between adjacent pins or balls) is only 10 microns.
Besides the HDI microvias, IC substrates and probe cards require conformal shielding to protect them from electromagnetic interference.
A conformal shielding is a conductive mask connecting with the ground layers of the IC substrates and probe cards so that the board won't be affected by electromagnetic from the external.
Solder mask of IC Load Boards
IC substrates and probe cards require a very good flatness of the solder mask. For the fabrication of IC substrates, probe cards, and high-density PCBs, the one-stop PCB manufacturer PCBONLINE uses the PSR-800 AUS SR1 dry film solder mask ink for solder mask coating.
The excellent performance of the PSR-800 AUS SR1 ink can ensure the integrity of the solder mask bridge and the flatness and gloss of the overall solder mask surface.
IC Substrate and Probe Card PCB Manufacturer -- PCBONLINE
For IC substrates and probe card fabrication without a quantity limit, you can work with the one-stop advanced PCB manufacturer PCBONLINE. PCBONLINE, founded in 1999, has two large advanced PCB manufacturing bases and one PCB assembly factory.
Here are PCBONLINE's advantages in IC load boards and other advanced PCBs:
- PCBONLINE grasps mature wire bonding and flip-chip bonding technologies.
- PCBONLINE has successful experiences in IC substrate and probe card fabrication.
- PCBONLINE fabricates all types of PCBs from prototype to bulk production, including IC substrates, probe cards, AlN PCBs, alumina PCBs, MCPCBs, HDI PCBs, high-frequency PCBs, FPC, and rigid-flex PCBs.
- The minimum pitch (center-to-center distance between adjacent pads) and solder mask bridge tolerance from PCBONLINE are 0.05mm, which is of high accuracy.
- Free one-on-one engineering support and customer services throughout your project.
PCBONLINE is a private-owned PCB company certified with ISO, IPC, IATF, REACH, RoHS, and UL. If you need IC load boards or any other PCBs, PCBA, or box-build assembly, you can send your Gerber and requirements to info@pcbonline.com to get a quote.
Conclusion
IC substrates and probe cards are the most advanced PCBs. IC substrates are the base board in IC packaging to connect the IC with the PCB. Probe cards are used in IC testing. They are high-density and require conformal shielding and very flat solder masks. The fabrication of IC substrates and probe cards is extremely complex. For IC substrates and probe cards, you can consider the one-stop advanced PCB manufacturer PPCBONLINE.
© This article is an original work of the PCBONLINE team. Please indicate the author PCBONLINE if you reprint. If the article is reproduced without permission or indicating the author's source, PCBONLINE reserves the right to investigate the infringement.
