Epoxy Mold Compound Cleaning Cycle Cleaners & Conditioners

How to Clean Epoxy Molding Compound with Melamine and Rubber Cleaning Sheets


When using Epoxy Mold Compound (EMC), what is the proper cleaning procedure to follow to ensure a proper mold cleaning, while avoiding wasting valuable production uptime?  How many shots of melamine and/or mold conditioner are needed for a proper cleaning?  These are the standard questions that we get asked regularly by new process engineers and operators.

Below is the recommended cleaning procedure:

Please visit us at www.caplinq.com to learn more about our whole range of epoxy molding compounds including our semiconductor-grade epoxy molding compounds, our fiberglass-reinforced industrial molding compounds, and our optically clear epoxy mold compounds (CMC).

We can also help support you to select and use the proper melamine-based epoxy mold cleaners, as well as rubber-based cleaners and conditioners.  If you have any other questions about how best to clean your molds, the products you can best use to clean them, or the application methods of these materials, please feel free to leave a comment below, or don’t hesitate to contact us.

About Chris Perabo

Chris is an energetic and enthusiastic engineer and entrepreneur. He is always interested in taking highly technical subjects and distilling these to their essence so that even the layman can understand. He loves to get into the technical details of an issue and then understand how it can be useful for specific customers and applications. Chris is currently the Director of Business Development at CAPLINQ.

21 thoughts on “How to Clean Epoxy Molding Compound with Melamine and Rubber Cleaning Sheets

  1. I’ve read your website regarding the cleaning procedure here.

    I want to ask the type of melamine and conditioner that supposes to be use for the cleaning, thanks.

  2. hello! i’m a process engineer in one of the semiconductor companies here in the philippines. the steps 1 – 4 you have posted are the normal die cleaning in semiconductor molding process. but most in the molding process, after die cleaning, after the operator have conducted 2 shots dummy, there are presence of incomplete mold/incomplete filling (or mizyuuten, in japanese term) especially in the corners of each cavity. it will only remove if the operator/technicians/engineers will manually clean the cavity that are affected by using a copper rod. one of our countermeasure is that, we substituted the melamine (cleaning resin) and conditioner (wax resin) with a rubber cleaning materials but after die cleaning using rubber cleaner, there are presence of plastic compound at the walls of each cavity. and again, it will only remove if the operator will clean manually the affected cavity. we use KTMC rubber cleaner here in our company. can you give me other makers or suppliers of rubber cleaning materials? thanks

  3. I would’t suggest rubber clean becasue that quite high release odor when compare with melamine which high risk operator get it and accumulate became toxic into health.

  4. Yazid

    You can ask Melamine supplier to get the suite cure time.
    note: Different melamine supplier so that different curetime….

  5. Hello,

    I am working for a company that is just starting to get into plastic assembly. How often do people typically perform cleaning procedure (every couple hours, every working shift, every day?) ? I am using Hitachi CEL-9240-HF10 for our mold compound and have only been able to achieve roughly ~30 shots on our semi auto-mold, but the supplier says upwards to 100 shots is possible. Any suggestions on how we can improve this? Any feedback/knowledge that would be helpful on someone just getting into the semiconductor industry would be helpful. Thank you

  6. Hello Russell,

    Epoxy mold compound cleaning cycles vary depending on many variables, including but not limited to: epoxy mold compound, size of part, age of mold, frequency and quality of the epoxy mold conditioning compound and the epoxy mold release agent used. The Hitachi CEL-9240 epoxy mold compound is a well-known epoxy for QFP, SOP, QFN, PLCC on leadframe devices. I agree with the supplier (Hitachi) that it is possible to run upwards of 100 shots before cleaning, but this depends a lot on how small the parts are and how tight the cavities are.

    The first thing I would do is look at the age and quality of the molds. Before you start, are the molds new or already pretty used? (Older molds need more frequent cleaning). Next, how clean are the molds? Are they really very clean before you start running epoxy mold compound again? (You should typically run 2-3 cycles of cleaning). And next, are you using any epoxy mold conditioning after cleaning? (Conditioning pre-conditions the mold with wax to make cleaning cycles less frequent. Finally, are you using any Epoxy Mold Release Agent? (If you use a spray between molds, you will decrease the frequency of the mold cleaning cycles required.

    Caplinq now supplies Cleaners, Conditioners and Lubricants for Epoxy Molding Compounds including our own brand of Linqsheet Mold Cleaning and Conditioning Sheets, our LinqWax Carnauba Wax Aerosol Spray and our LinqSil Silicone Mold Release Spray. Please contact us for any questions related to cleaning or conditioning products for epoxy or thermoset molding.

  7. Hey Chris

    Thanks for the feedback that is much appreciated. May be off topic, but I have been trying to find a standard in which determines how much desiccants should be used to when de-thawing the materials (mold compound, cleaner conditioner). Not sure what would be used to determine that whether it would be amount of materials, or size of bag. If anyone had information on this it would be greatly appreciated.

  8. Hi Russell,

    Yes, this is off-topic, but happy to help 🙂 I also do not know of any standard, but I really don’t think it’s necessary. Epoxy Mold Compounds, or Epoxy Mold Conditioners should always come inside a plastic bag inside a secondary packaging (either a cardboard box or a plastic pail). The thaw time needed to thaw even the largest (25kg) packaging is 24 hours. You shouldn’t thaw either epoxy mold compound or Epoxy mold conditioner longer than this (for 5-10 kg packing 8 hours is also plenty).

    When you take out the box to thaw DO NOT OPEN THE PLASTIC BAG. This is the most important. Moisture can absorb into the epoxy mold compound during the thaw period, but only if the plastic bag is open. Moisture comes from the condensation of the (warm) atmosphere onto the (colder) plastic packaging. Moisture will not penetrate the plastic bag, so there are no additional desiccants necessary. Hope this answers your question.

  9. Hey Chris

    Thanks for the feedback that helps clear a lot of information up. Due to production size being quite small at this moment, as well as not having a cold room, there are a couple concerns that arise for me.

    As a result of our production size being quite small, we generally have to weigh out the amount of materials from the packaging, so we do not waste unused materials. As a result, the plastic packaging is opened to weigh out the materials. What method would you consider best in reducing the probability of moisture getting inside the mold compounds? As I stated, we do not have a cold room so that is not currently a option.

    Thanks a lot Chris. I just found this blog and have found extremely helpful information already.


  10. Glad you find the information useful, Russell. Please come back often 🙂

    I’m concerned if you do not have a cold room at all. For small volume production, even a chest fridge or freezer is perfectly suitable. For a couple hundred bucks, you should consider the investment (I’m sure the small volumes of epoxy mold compound will cost as much!). Anything that goes to 10C (standard fridge) is fine, but a -20C chest freezer, will do no harm to the epoxy and can even extend shelf life. If you need to open the packaging to weight out material, you should do this in the cold storage. This isn’t the “ideal” advice as opening and closing plastic bags is not ideal (though all small volume manufacturers do it anyway), but if your epoxy mold compound is in the freezer, you are better off to open and close the plastic in the freezer. This way, there is no moisture as a result of condensation.

    What you could do if this is available to you, is to put the material you have removed into a “nitrogen chamber” (a so-called dry-box), which is even better than any desiccant. Considering you said the volumes were small, this should be possible. If there is no nitrogen chamber – then I find a desiccant is pretty useless. There won’t be enough time to “suck the moisture” out.

  11. Hey Chris

    Great information. Currently we have a freezer (-50C) that all the material is stored in. I am going to see if we can incorporate the dry box, as well as change the procedures to weighing the material in the freezer itself.

    In addition, currently we are using transfer cleaner + transfer conditioning pellets. As a result, the cavities of our mold tend to be quite clean, but the outside of the cavities itself is starting to get dirty. Because we are using the transfer cleaning pellets, what methods do people use in cleaning the outside of the cavities when using cleaning pellets? The reason we are using cleaning pellets, is our mold has vacuum holes, thus compression grade cleaners + conditioners have been clogging the vacuum holes, and making it hard to clean. Thanks guys


  12. Hi Russell,

    Weighing the material in the freezer is not a terrible idea – but -50C is a cold place to do it!

    Transfer cleaning and transfer conditioning is a standard practice for sure. As you mention though, it will not clean the outside of the cavities.

    Even manufacturers with vacuum holes (most molds do have vacuum holes) use compression cleaners to clean the outside of the cavities. You do not need to do it every cleaning cycle, but it’s still a good idea to do it to clean the areas outside if the runners.

  13. Thanks for you share. we are know that the mould dirty resin consists of two layers , the second layers can be removed by using melamine and sheet, but the first layer is abnormal stubborn, how to release this layer by simply method. thanks.

  14. Hello,

    I have originally just been using a transfer grade cleaner + conditioner + two dummy shots prior to going into production. However, it has been noticed that the outside surfaces of the mold are starting to build up a good amount of staining, and has been transferring onto the shoulder leads of the packages.

    As a result of our mold having vacuum holes, it was recommended that we use a rubber based compression sheet vs a melamine based. In terms of reducing the clogging in the vacuum holes, what can we do to reduce the possibility of the holes getting clogged other than turning off the vacuum draw?

  15. We have a new product and it requires overmold,the 1st shot using dummy the appearance was good, no sign of defectt but when we proceeded to a good units after mold it becomes more in the surface and most likely not acceptable anymore. Now my concern is is it advisable to clean the lower mold chase frequently or it has a frequency of cleaning,By the way we use dow corning as a rubber sheet cleaning.

  16. The frequency of cleaning is dependent on many variables including the type of epoxy molding compound used, the design of the mold chase and the cleaning compounds used. Typically, the frequency is determined by a trial-and-error method – starting with fewer cleanings and then going to more regular cleaning. If the mold is cleaned, extend the number of cleanings done until you get insufficient results and then dial it back. If you can advise the Epoxy Mold Compound used, the package type and the grade of Dow Corning Rubber Cleaning Sheet, we might be able to advise more specifically.

    Alternatively, CAPLINQ also offers Epoxy Molding Compound and Rubber Cleaning Sheets that we have designed to work well together.

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