-
- News
- Books
Featured Books
- smt007 Magazine
Latest Issues
Current IssueComing to Terms With AI
In this issue, we examine the profound effect artificial intelligence and machine learning are having on manufacturing and business processes. We follow technology, innovation, and money as automation becomes the new key indicator of growth in our industry.
Box Build
One trend is to add box build and final assembly to your product offering. In this issue, we explore the opportunities and risks of adding system assembly to your service portfolio.
IPC APEX EXPO 2024 Pre-show
This month’s issue devotes its pages to a comprehensive preview of the IPC APEX EXPO 2024 event. Whether your role is technical or business, if you're new-to-the-industry or seasoned veteran, you'll find value throughout this program.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - smt007 Magazine
Advanced Printing for Microelectronic Packaging
March 11, 2015 | Kenneth H. Church, Xudong Chen, Joshua M. Goldfarb, Casey W. Perkowski, Samuel LeBlanc, nScrypt Inc.Estimated reading time: 16 minutes
A number of important printing factors need to be considered when printing fine lines. One is the diameter of the pen tip. Typically the inner diameter does not set the width of the dispense feature; this is usually set by the out diameter of the pen tip. In addition, there is a slumping issue. Most shear thinning materials will slump after being printed. Therefore to print a fine feature such as 100 microns, it is many times necessary to go to a smaller pen tip such as a 50/75. This implies 50 micron inner diameter and 75 micron outer diameter. Additionally, it will be important to get in proximity of the substrate. Proximity is affected by the pen tip diameter. If the diameter is very large (hundreds to thousands of microns) then the gap set between the pen tip and the substrate can be very large. The volume being dispensed will be very large. If the desire for small features is important, then the small gap will be important. Gaps on the order of microns and tens of microns can have an effect on printing as well. The flow rate for dispensing can be affected by the gap.
The flow rate of the pump (which determines the dispensed feature size) depends on the value of the pressure, the valve opening and the size of the tip orifice. Engineers and researchers at the company also discovered that the dispensing height (the gap between the dispensing nozzle tip and the substrate) plays a crucial role in the dispensing volume and especially when the feature size gets smaller or thin lines are printed. For these types of features the nozzle tip needs to be closer to the substrate. This will increase the flow resistance and thus reduce the flow rate. It is expected that the pressure drop will be dominated by the dispensing gap when the gap is 50% smaller than the tip size. By applying the above mentioned CFD (Computational Fluid Dynamic) model at various dispensing heights (Figure 2), the flow rates were calculated [5].
Figure 2. Schematic drawing of the CFD model.
The pressure drop with different dispensing heights is plotted in the Figure 3. At a very small gap (Figure 3a), the pressure
drop is dominated by the substrate. At a large gap (Figure 3c), the pressure drop is mainly determined by the tip orifice.
There is a transient region (Figure 3b) where the pressure drop is affected by both of them.
Figure 3. Pressure drop vs. different dispensing height. (a) 5 microns. (b) 15 microns. (c) 30 microns.
The flow rate vs. dispensing height is plotted in the Figure 4. It can be seen that the flow rate increases to a steady state value at the dispensing height that is proportional to the value of the pen tip diameter. The pressure moves the steady state flow rate with the lowest pressure achieving steady state the fastest. It is also obvious that the flow rate is sensitive to a change in dispensing heights if they are below a certain value (50 microns in this case). The lower the dispensing height, the more it affects the flow rate.
Figure 4. Flow Rate versus Dispense Height
Page 2 of 3
Suggested Items
Indium Corporation Expert to Present on Pb-Free Solder for Die-Attach in Discrete Power Applications
04/30/2024 | Indium CorporationIndium Corporation Product Manager – Semiconductor Dean Payne will present at the Advanced Packaging for Power Electronics conference, hosted by IMAPS, held May 8-9 in Woburn, Massachusetts, USA.
Taiyo Circuit Automation Installs New DP3500 into Fuba Printed Circuits, Tunisia
04/25/2024 | Taiyo Circuit AutomationTaiyo Circuit Automation is proud to be partnered with Fuba Printed Circuits, Tunisia part of the OneTech Group of companies, a leading printed circuit board manufacturer based out of Bizerte, Tunisia, on their first installation of Taiyo Circuit Automation DP3500 coater.
Vicor Power Orders Hentec Industries/RPS Automation Pulsar Solderability Testing System
04/24/2024 | Hentec Industries/RPS AutomationHentec Industries/RPS Automation, a leading manufacturer of selective soldering, lead tinning and solderability test equipment, is pleased to announce that Vicor Power has finalized the purchase of a Pulsar solderability testing system.
AIM Solder’s Dillon Zhu to Present on Ultraminiature Soldering at SMTA China East
04/22/2024 | AIMAIM Solder, a leading global manufacturer of solder assembly materials for the electronics industry, is pleased to announce that Dillon Zhu will present on the topic: Ultraminiature Soldering: Techniques, Technologies, and Standards at SMTA China East. This event is being held at the Shanghai World Expo Exhibition & Convention Center from April 24-25.
AIM to Highlight NC259FPA Ultrafine No Clean Solder Paste at SMTA Wisconsin Expo & Tech Forum
04/18/2024 | AIMAIM Solder, a leading global manufacturer of solder assembly materials for the electronics industry, is pleased to announce its participation in the upcoming SMTA Wisconsin Expo & Tech Forum taking place on May 7 at the Four Points by Sheraton | Milwaukee Airport, in Milwaukee, Wisconsin.