When it comes to die attach processes in semiconductor packaging, precision is everything. High-performance epoxies like Henkel’s LOCTITE ABLESTIK 84-1LMI and LOCTITE ABLESTIK 8361J are trusted for their reliability in bonding microchips and ensuring long-term performance in electronics. But even the best materials can underperform if the dispensing process isn’t dialed in.
One question that often comes up: Should you remove the syringe plunger before loading it into your die attach equipment?
The answer isn’t a simple yes or no—it depends on your equipment, the material, and how you handle the process. In this blog, we’ll explore the pros and cons of removing the syringe plunger, share best practices for dispensing Henkel’s die attach epoxies, and offer troubleshooting tips for common issues like dripping. Whether you’re using a high-precision die bonder like the ESEC S2100 or another system, these insights will help you optimize your workflow.
Removing the syringe plunger before setting it on a dispensing machine is a practice some manufacturers follow for specific reasons:
- Relieving Pressure: It can help vent trapped air, ensuring a smoother flow of material.
- Machine Control: Some systems, like the ESEC S2100, use time-pressure or positive displacement dispensing, applying pressure directly from the top of the syringe barrel. Removing the plunger allows the machine to take full control without interference.
- Preventing Overdispensing: Dual pressure from both the plunger and the machine can lead to messy overdispensing.
For equipment like the ESEC S2100, which is widely used in advanced semiconductor packaging, manufacturers often recommend removing the plunger to ensure the system operates as intended. However, this step comes with risks that need to be carefully managed.
Risks of Removing the Syringe Plunger
While removing the plunger can make sense for certain setups, it’s not without potential pitfalls. Here’s why most dispensing systems—and Henkel—generally advise keeping the plunger in place:
Exposing the die attach paste to the environment increases the risk of contamination, which can compromise the performance of epoxies like LOCTITE ABLESTIK 84-1LMISR4. Additionally, removing the plunger can introduce air bubbles, leading to dispensing inconsistencies and potential voids after curing—issues that can affect reliability in critical applications.
In highly filled systems like LOCTITE ABLESTIK ABP 8064T, leaving the syringe upright without a plunger might allow heavier filler components to settle, altering the material’s consistency and allow material separation. Also, some systems rely on vacuum to hold the epoxy in place when idle. Without the plunger, this vacuum can be disrupted. Finally, mishandling during plunger removal can lead to spills or leaks, wasting valuable material.
The plunger plays a crucial role in maintaining material integrity, preventing air exposure, and keeping the epoxy stable during storage and transport. For these reasons, Henkel typically recommends leaving the plunger in place unless your equipment specifically requires its removal.
Best Practices for Plunger Removal
If your die attach equipment, like the ESEC S2100, requires removing the syringe plunger, follow these steps to minimize risks:
- Prepare a Clean Workspace: Clean the area around the machine and wear electronics-grade, silicone-free gloves to avoid contaminating the epoxy.
- Keep the Syringe Upright: When removing the plunger, ensure the syringe is upright to prevent material from spilling or separating.
- Cap Immediately: After removing the plunger, quickly insert the cap and load the syringe into the machine to limit air exposure.
- Purge the System: Prime or purge the system to eliminate any trapped air, ensuring consistent dispensing.
By following these steps, you can safely use epoxies like LOCTITE ABLESTIK 8361J in systems that require plunger removal, while reducing the risk of issues like air entrapment or contamination.
If you’re experiencing dripping during dispensing—whether the plunger is removed or not—the issue likely isn’t related to the plunger itself. Here are some common culprits and how to address them:
- Barrel Pressure: Excessive pressure, especially when the machine is idle, can cause dripping. Reduce the pressure to find a balance that prevents leaks while maintaining flow.
- Needle Gauge Size: A larger needle opening (lower gauge number) can lead to uncontrolled flow. Try a smaller opening (higher gauge number) for better control, especially with lower-viscosity epoxies.
- Suck-Back Pressure or Vacuum: Enable or fine-tune the suck-back pressure or vacuum settings on your machine. This is particularly effective for preventing tailing and dripping.
- Material Condition and Handling: Ensure you’re following the thawing procedure outlined in the Technical Data Sheet (TDS). Improper thawing can affect the epoxy’s viscosity and dispensing behavior.
- Purge After Installation: Fully purge the material after loading the syringe to release any internal pressure or imbalances in the dispensing system.
By addressing these factors, you can achieve precise, drip-free dispensing with Henkel’s die attach epoxies, ensuring clean and reliable bonding for your components.
The way you handle the syringe plunger can make or break your die attach process. Keeping the plunger in place offers key benefits, like maintaining material integrity and preventing air exposure, which are essential for the performance of epoxies like LOCTITE ABLESTIK 84-1LMI in high-stakes applications. However, if your equipment requires plunger removal, strict handling procedures can help mitigate the risks.
Why Consider Removing the Syringe Plunger?
Deciding whether to remove the syringe plunger when dispensing Henkel’s die attach epoxies comes down to your equipment and process requirements. For most systems, keeping the plunger in place is the safest bet to maintain material integrity and avoid issues like contamination or air entrapment. But if your setup—like the ESEC S2100—requires plunger removal, following strict handling procedures will help you get the best results.
If you’re dealing with dispensing challenges like dripping, take a closer look at your machine settings and material handling practices. Products like LOCTITE ABLESTIK 8361J and LOCTITE ABLESTIK 84-1LMI are engineered for precision, and with the right approach, you can ensure they perform at their best.
For more guidance on optimizing your die attach process, reach out to our technical support team.
Disclaimer: This blog is a general guide. Always refer to Henkel’s Technical Data Sheets (TDS) and your equipment manufacturer’s guidelines for specific instructions. Henkel makes no warranties, expressed or implied, regarding product use.
