How thick is Polyimide Tape?

Chris Perabo

Poly­imide Tape (the gener­ic ver­sion of Dupont© Kap­ton Tape), typ­i­cal­ly comes in var­i­ous poly­imide thick­ness­es. These thick­ness­es are gen­er­al­ly labelled as 1‑mil, 2‑mil, 3‑mil or even 5‑mil thick poly­imide tape. Each of these vari­a­tions serves dif­fer­ent pur­pos­es and is there­fore used for dif­fer­ent appli­ca­tions. Of course, the thick­er the poly­imide film used, the more expen­sive the tape too.

Each lay­er has a thick­ness and the sum of these thick­ness­es makes up the total tape thickness.

What is often mis­un­der­stood by cus­tomers is what exact­ly “1‑mil thick” poly­imide tape implies. Cus­tomers are not sure whether “1‑mil” (25µm) thick poly­imide tape refers to the poly­imide film thick­ness or the total thick­ness, since ulti­mate­ly poly­imide tape is made up of both the poly­imide film lay­er plus the sil­i­cone adhe­sive lay­er (read more about why we believe in sil­i­cone-based tapes here).

Polyimide Kapton Tape Silicone Build

As can be seen in the pho­to (click to enlarge), poly­imide tape is made­up of two dis­tinct layers:

  1. The poly­imide (kap­ton) film layer
  2. The adhe­sive (sil­i­cone) layer

Each lay­er has a thick­ness and the sum of these thick­ness­es makes up the total tape thickness.

The Polyimide (Kapton) Film Layer

This is the lay­er that is spec­i­fied in the prod­uct descrip­tion. For exam­ple, 1‑mil tape (referred to as LINQTAPE PIT1 by CAPLINQ) has a poly­imide film lay­er of 1 mil (25µm). Sim­i­lar­ly, 2‑mil tape has a poly­imide film lay­er of 2 mil (50µm), 3‑mil tape has a poly­imide film lay­er of 3 mil (75µm) and so on. This is in fact the lay­er that deter­mines the thick­ness used in the description.

The Adhesive (Silicone) Layer

This is the lay­er of sil­i­cone adhe­sive applied to the back­side of the poly­imide (kap­ton) film. Though this lay­er thick­ness can vary, the stan­dard aver­age thick­ness is 1.6 mil (40um). Of course, there is some vari­a­tion in this adhe­sive thick­ness and the thick­ness can actu­al­ly range between 35µm — 45µm (1.4 — 1.8 mil) though his­tor­i­cal data sug­gests that the actu­al range is betweeen 40µm — 45µm (1.6 — 1.8 mil). For all intents and pur­pos­es, 1.6 mil (40µm) can be used as the sil­i­cone adhe­sive lay­er thickness.

Of course, this assumes sin­gle sided poly­imide (Kap­ton) tape. Since CAPLINQ also sup­plies dou­ble-sided Poly­imide (Kap­ton) Tape (referred to as LINQTAPE PITD2 by CAPLINQ) this tape would have adhe­sive lay­ers on both sides of the poly­imide film lay­er in fact dou­bling the adhe­sive thick­ness of the dou­ble-side poly­imide tape from 1.6 mil (40µm) to 3.2 mil (80µm).

The total thick­ness is then the sum of these two lay­ers. For exam­ple, as can be inferred by the name, LINQTAPE PITD1 is 1‑mil dou­ble-sided poly­imide (kap­ton) tape that has a poly­imide film lay­er of 1 mil (25µm) and two adhe­sive lay­ers of 1.6 mil (40µm) each for a total thick­ness of 4.1 mil (25µm + 40µm + 40µm = 105µm) . Like­wise, 1‑mil (LINQTAPE PIT1) tape has a total thick­ness of 2.6 mil (65µm), 2‑mil (LINQTAPE PIT2) tape has a total thick­ness of 3.5 mil (90µm), and so on.

Con­tact us or vis­it us at www.caplinq.com today for more infor­ma­tion on these or oth­er products.

Relat­ed posts:

  1. PIT0.5S: 0.5mil Poly­imide Film with Sil­i­cone Adhe­sive Many cus­tomers have request­ed whether CAPLINQ can offer thin­ner poly­imide tapes. CAPLINQ is pleased to announce LINQTAPE PIT0.5S a 0.5mil (13…
  2. How is Poly­imide Pres­sure Sen­si­tive Tape Made? Poly­imide pres­sure sen­si­tive adhe­sive (PSA) tape is actu­al­ly made up of two sep­a­rate steps. The first is the man­u­fac­ture of…
  3. Dou­ble-sided poly­imide tape with ultra-thin sil­i­cone adhe­sive lay­er Recent­ly, we were asked if CAPLINQ sup­plied a tape with the fol­low­ing spec­i­fi­ca­tions: Adhe­sive: 17um Sil­i­cone adhe­sive Poly­imide Back­ing Car­ri­er: 25um…

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.
See all posts by Chris Perabo 

4 thoughts on “How thick is Polyimide Tape?”

  2. Poly­imide tape (Kap­ton) is a very rigid mate­r­i­al and can sup­port a great deal of com­pres­sion. Even a heavy com­pres­sion like the one men­tioned above will do lit­tle to reduce the thick­ness of a poly­imide tape. This is par­tic­u­lar­ly true of thin­ner (ie. 1 mil or 25um) Poly­imide Tape backing.

    This being said, the adhe­sive will see some dis­place­ment, and will make up most of the thick­ness reduction. 

    As with most bond­ing appli­ca­tions under pres­sure, even high pres­sure will not com­plete­ly dis­place the adhe­sive, and we would expect the bond­line (ie the adhe­sive lay­er) to main­tain at least 20µm of thickness.

    There­fore, to answer your ques­tion: a 65µm Kap­ton tape under heavy com­pres­sion should still have a total thick­ness of 40µm.

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