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The Most Advanced PCB: IC Load Board amd Probe Card


Thur, Oct 20, 2022

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An IC load board is used for carrying bare integrated circuits (IC) and connects the IC to the main printed circuit board (PCB). In the PCB industry, we consider it the most advanced PCB. As a one-stop advanced PCB manufacturer, how can we not introduce IC load boards to you?

IC tester load board

What is an IC Load Board

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.

To let a bare IC work and protect it from thermal, vibration, dust, moisture, and chemical, you will have it tested and packaged with an IC load board and a plastic/ceramic/metal enclosure.

IC packaging structure

An IC load board, a double-sided ultra HDI PCB, is the base board used in IC testing or packaging. 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.

IC load board bonding

In IC testing, bare ICs are placed on an IC load board to inspect the circuit conductivity and functions to ensure their quality.

After testing, a bare IC is packaged with an IC load board and plastic/ceramic/metal enclosure.

As you can see, an IC load board is critical for the IC industry.

Currently, IC load boards take up about 10% of the PCB market value. Together with a high-frequency base station backplane, the IC load board has top complexity and is considered the most advanced PCB option.

What Functions Does An IC Load Board Play?

ICs are thermally sensitive components. Too much thermal accumulated in the IC can reduce the IC efficiency and even burns it. With an IC load board, thermal dissipates quickly through it to the main PCB and the air so that the IC can work efficiently without thermal affection.

Besides thermal dissipation, an IC load board provides mechanical protection to the IC from vibration and stress.

The main function of an IC load board is connecting the IC with the PCB. With the IC load board, the whole IC is a surface mount device (SMD) and can easily mount on the PCB with other SMDs.

Sometimes, an IC load board can even be embedded with passive and active components to achieve some system functions.

Types of IC Load Boards

IC load boards belong to PCBs, and they are also composed of a PCB substrate, copper conductive layers, and prepreg layers.

IC load board

According to different substrate materials, IC load boards are classified into three types -- rigid, flexible, and ceramic IC load boards.

Rigid IC load boards are the most common IC load boards. The substrate materials for rigid IC load boards include bismaleimide triazine resin (BT resin), Ajinomoto build-up film (ABF), and molded interconnect substrate (MIS). BT IC load boards are used for FPGA (field-programmable gate array) and high-reliability network chips. ABF IC load boards are used for large high-level chips such as CPU, GPU, and chipset. MIS IC load 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 load 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 load boards include semiconductor lighting, laser, optical communications, aerospace, automotive electronics, and deep sea drilling.

Features of IC Load Boards

IC load boards 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 load board HDI

IC load boards belong to HDI PCBs but are more complex. The finest pitch (center-to-center distance between adjacent pins or balls) is only 0.05mm. Besides the HDI microvias, IC load boards require conformal shielding to protect the IC load boards from electromagnetic interference.

A conformal shielding is a conductive mask connecting with the ground layers of the IC load boards so that the board won't be affected by electromagnetic from the external.

Solder mask of IC Load Boards

IC load boards require a very good flatness of the solder mask. For the fabrication of IC load boards and fine-pitch 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 Load Board and One-Stop Advanced PCBA Manufacturer -- PCBONLINE

For IC load board production without a quantity limit, you can turn to the one-stop advanced PCB manufacturer PCBONLINE. PCBONLINE, founded in 1999, has two large advanced PCB manufacturing bases and one PCB assembly factory.

IC load board supplier

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 load board fabrication.
    • PCBONLINE fabricates all types of PCBs from prototype to bulk production, including IC load boards, AlN PCBs, alumina PCBs, MCPCBs, HDI PCBs, high-frequency PCBs, FPC, rigid-flex PCBs, and high-Tg FR4 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-own 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.


IC load boards are the most advanced PCBs and are the base board in IC packaging to connect the IC with the PCB. It is high-density and requires conformal shielding and very flat solder masks. The fabrication of IC load boards is extremely complex, and for IC load board fabrication, 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.