In a previous article, we talked about how epoxy molding compound pellets have specific aspect ratios. In this article, we will explain in more detail how epoxy molding compounds pellets have their sizes defined.
As you can imagine, each pellet diameter requires a new mold tool. The only way to get other diameter pellets is to have a whole new mold made. Epoxy Mold Compound manufacturers have many such molds made, namely in sizes ranging from 10mm to 70mm in diameter.
The weight of the pellet on the other hand are determined by packing more or less material into the diameter hole. More weight makes the pellets “taller” while less weight makes them shorter. “Tall” pellets are susceptible to breakage as the aspect ratio does not lend itself to very tall pellets before they start breaking in delivery. The reason the weight is given as opposed to the height of the pellet is because the inspection machine checks the weight of each pellet, not the height. Furthermore, each epoxy molding compound has its own specific gravity (density), so the height could be different for different epoxy mold compounds.
The table below gives a typical selection of available pellet sizes, diameters and weights.
| Pellet Diameter | Pellet Weight Range (grams) | |||
|---|---|---|---|---|
| Millimeters | Inches | Minimum | Maximum | |
| Micro Pellets | 5 | 0.197 | 0.5 | 1.9 |
| 5.7 | 0.224 | 0.6 | 2.2 | |
| 8.5 | 0.335 | 0.9 | 3.3 | |
| Mini Pellets | 10 | 0.394 | 1.1 | 4.1 |
| 11 | 0.433 | 1.3 | 4.5 | |
| 12 | 0.472 | 1.6 | 5.7 | |
| 13 | 0.512 | 1.7 | 6.5 | |
| 14 | 0.551 | 2.1 | 7.8 | |
| 14.3 | 0.563 | 2.2 | 8.2 | |
| 16 | 0.63 | 2.5 | 10.2 | |
| 18 | 0.709 | 3.5 | 12.9 | |
| 20 | 0.787 | 3.7 | 15.9 | |
| 25 | 0.984 | 4.9 | 20.3 | |
| Conventional Pellets | 35 | 1.375 | 14 | 105 |
| 38 | 1.496 | 16 | 125 | |
| 40.6 | 1.6 | 20 | 150 | |
| 45 | 1.75 | 25 | 175 | |
| 48 | 1.9 | 28 | 280 | |
| 55 | 2.165 | 36 | 360 | |
| 58 | 2.28 | 40 | 400 | |
| 61 | 2.4 | 45 | 445 | |
| 70 | 2.75 | 55 | 580 | |
| Note 1: Pellet weight specification tolerances and epoxy mold compound specific gravity must be considered when determining capability. | ||||
According to the table above, the limit to the weight (and thus height) of a 20mm epoxy pellets is 15.9 grams. In order to offer larger weights, we need to offer different diameters that allow for the weights you require. So if there is a diameter you can work with, the weight can be adjusted upward until a certain maximum. There is also a necessary minimum as the table explains, below which the opposite aspect ration has a similar negative effect of broken pellets.
Please visit us at www.caplinq.com to learn more about our whole range of epoxy mold compounds including our semiconductor-grade epoxy mold compounds, fiberglass reinforced epoxy mold compounds, optically clear epoxy mold compounds. If you have any other questions about epoxy molding compound pellet sizes, please feel free to leave a comment below or don’t hesitate to contact us.
