A Process for Increasing the Bonding Productivity of Thermally Conductive Tapes Using a Seamless Die-Cut Design and Simultaneous Bonding of Multiple Parts
Publication Date: 2014-Jun-05
The IP.com Prior Art Database
This article describes a convenient bonding process for various substrates using thermally conductive tapes. The process is demonstrated by bonding a series of voltage regulators and heat sink pairs, simultaneously. The process employs a jig to bond the components, simultaneously, to improve productivity. Another benefit is to improve tape utilization by using a seamless die-cut design during tape converting to avoid/minimize the amount of wasted tape (weed) in the die cutting process. By using this process, bonding productivity may be increased 40% or greater.
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Thermally conductive adhesive transfer tapes are used to provide not only a bonding solution, but also a preferential heat-transfer path between heat-generating components and heat sinks. The tapes are typically acrylic pressure sensitive adhesives (PSA) containing thermally conductive ceramic fillers. The tapes can be used in power supply, hand-hold electronics, panel television and high-power light emission diode (LED) applications to provide a cleaner process, replacing other thermal interface solutions such as thermal grease. Figure 1 shows one specific application, the use of a thermal interface material in a regulator of a power supply.
Thermal conductive tape
Figure 1. Regulator in power supply and (b) thermal conductive solution.
In order to improve the contact of the tape to the substrates to be bonded, some thermally conductive tapes do not have a carrier. However, in these configurations, it is sometimes difficult to delaminate the first release liner from the adhesive, due to the softness of the adhesive. This is particularly true when the application requires a seamless design of the die-cut, to maximize tape usage, i.e. minimize waste, due to cost concerns. In the seamless die-cut design, there is no gap region available between die cut to facilitate removal of the release liner. This can lead to assembly issues that can have a significant effect on productivity. In these cases, an appropriate tab to facilitate liner removal along with an optimized assembly procedure may be desired.
New Assembly Process:
The new process to attach several seamless die-cuts simultaneously, with minimal/no tape loss, is shown in Figures 2 to 5. The adhesive transfer tape is first die-cut seamlessly and the top release liner is removed and replaced by a new release liner having the appropriate alignment holes that will match with the pins of a series of regulators. Tabs are added to the top and bottom liners, to facilitate liner removal at the appropriate time, Figures 2a and 2b.
Figure 2. Design of tape die cut for jig assembly (a) tape with top & bottom liners and
(b) top liner.
Figure 3a shows a typical regulator and corresponding slider. Figure 3b shows the next step in the process which is to align a series of sliders adjacent to one another and mounting the regulators on them, followed by applying the tape. After removing the bottom release liner, the
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transfer tape is applied to the regulators, aligning the alignment holes of the tape with the pins of the regulators to ensure that the tape is positioned properly. Although not shown in Figure 3, the sliders are mounted on a guide/jig.
Figure 3. (a) Slider for a regulator and (b) aligned regulators and attached tape with corresponding seamless die-cuts, the pins of regulators align with the alignment holes of the tape.
After removing the top release liner, the sliders are separated by expanding the jig which slides the regulators/slide...