Troubleshooting Resin bleed in Die attach

How to identify and fix resin bleed in Die attach applications

Resin Bleed is the migra­tion of liq­uid com­po­nents from the adhe­sive onto the sur­round­ing sur­face due to sur­face ener­gy dif­fer­ences between the resin and substrate.

It can be caused by sur­face con­di­tions such as the rough­ness or the clean­li­ness of the sub­strate. It can also be a result of unop­ti­mised process para­me­ters such as a wrong cure pro­file or too long dwell time.

Bleed onto the bond sur­face may cause poor wire bond­abil­i­ty. It may also improve or lessen the adhe­sion of encap­su­lants and mold­ing compounds.

Bleed or outgassing?

The first thing to check is to see if the issue is resin bleed or out­gassing. Under­stand­ing exact­ly what you are look­ing at will help make sure that it is being addressed prop­er­ly. Ask your­self these questions:

  • Is the dis­col­oration one sided or sym­met­ri­cal with­out a clear bound­ary between the lead­frame and the bleed?

Then it is like­ly out­gassing. You could increase the air­flow to try and resolve this.

  • Does the pat­tern run along the etches/ridges of the substrate? 

Then it is most like­ly bleed. In this case there should be clear sep­a­ra­tion between the dis­coloura­tion and the lead­frame. Try mod­i­fy­ing the cure pro­file, clean the sur­face area or exper­i­ment with oth­er materials.

One side, Sym­met­ri­cal and sep­a­rat­ed discoloration


We can gen­er­al­ly attribute resin bleed to 3 main fac­tors. Equip­ment, Process­es and Mate­ri­als. Fol­low­ing up we are list­ing the most com­mon caus­es and the cor­rec­tive actions that you could take to reduce resin bleed.


Pos­si­ble Caus­esCor­rec­tive action
Sur­faces may be too warmEnsure that the die attach is not warmed-up until ready for cure

 Make sure sur­faces are not overheated



  • Sur­face may be too rough
  • Sur­face may be dirty or unclean
  • Dwell time before cure is too long
  • Cure pro­file is too slow
Scan­ning elec­tron micro­scope (SEM) image of resin bleed


  • Mod­i­fy sur­face if pos­si­ble to reduce roughness
  • Clean sur­face pri­or to appli­ca­tion of die attach
  • Plas­ma clean­ing often helps reduce bleed
  • Increas­ing cure speed can help reduce bleed
  • Increas­ing cure tem­per­a­ture can help reduce bleed


Pos­si­ble Caus­esCor­rec­tive action
Die-attach may be par­tic­u­lar­ly sen­si­tive to bleed on a spe­cif­ic substrateDis­cuss with your CAPLINQ rep­re­sen­ta­tive to make sure you have made the cor­rect prod­uct selec­tion for your process

Over­all resin bleed and sep­a­ra­tion should not be an issue if the cor­rect mate­ri­als have been cho­sen and the process is opti­mised. There are mul­ti­ple mate­ri­als that have been devel­oped to almost elim­i­nate the chance of bleed­ing such as LOCTITE ABLESTIK QMI536NB and LOCTITE ABLESTIK 84–1LMISNB. Keep in mind that bleed­ing is not observed only in die attach but it can be found in any mate­r­i­al that uses a base resin.

Caplinq offers a Huge range of Henkel Elec­tron­ics Die Attach mate­ri­als, Encap­su­lants, Under­fills and Elec­tron­ics assem­bly adhe­sives. We can help you choose the ide­al non-bleed­ing mate­r­i­al for your appli­ca­tion. Con­tact us for more information. 

Did you find this blog inter­est­ing? Sign up to be noti­fied when­ev­er some­thing new comes up. We won’t spam you with ran­dom stuff. We hate it as much as you do.

About George Kountardas

George is a Jack of all trades with an unappeasable inquiring mind. Obsessed with new products and technologies, he is always pushing forward for better, faster and more efficient applications. Always learning something new.

Leave a Reply

Your email address will not be published. Required fields are marked *