Wire bonding has been inextricably linked to semiconductor assembly and connecting the chip with its package.
Today, wire bonding technology is used in PCB assembly simply because OEM demands are for increasingly smaller products and the boards they’re based on. Products like IoT devices and wearables are based on small rigid or a combination of rigid-flex circuits. Since the real estate is so small and limited, bare chips go on these boards and are connected via wire bonding (Fig. 1) to substrates or on the small board iteself.
Of utmost importance is wire bond reliability. To get more detail on wire bonding, check out our blog.
In the meantime, here are some tips and hints on getting a good handle on wire bond reliability.
- Maintain good metallization between the substrate and the die. This means having a clean surface with no oxidation to maintain good wire bond strength.
- Get assurances you’re using the right type wire for your application, whether it’s gold, aluminum, copper, or silver.
- Make sure chips are mounted properly. You have to make sure they are correctly mounted for the wire bond to be precise.
- Get an understanding of the necessary fixture for laying the substrate flat. The EMS Provider must be savvy enough to create accurate fixtures.
- Make sure the substrate surface is clean and not oxidized. Otherwise, wire bond strength will be jeopardized, resulting in poor reliability.
- A caveat when using gold wire is to get assurances stabilized gold is used. Stabilized gold is a mixture of beryllium and gold to increase wire bond life as long as it’s kept in an inert level like nitrogen.
These and other key aspects are critical when using wire bonding and assembling small PCBs for a variety of increasingly smaller products. It’s best to always collaborate with your experienced EMS Provider to determine which type of wire to use in your application. At the same time, find out more about the equipment and personnel on site that’ll be involved for your wire bonding projects.