Browse Prior Art Database

LTCC Module Array Transfer Mold Process Improvement

IP.com Disclosure Number: IPCOM000018884D
Original Publication Date: 2003-Aug-19
Included in the Prior Art Database: 2003-Aug-19
Document File: 5 page(s) / 785K

Publishing Venue

Motorola

Related People

Mark Gerber: AUTHOR [+2]

Abstract

The increasing interest for smaller and more integrated wireless solutions has led companies like Motorola to investigate LTCC based module array solutions. Low Temperature Co-fired Ceramics (LTCC) substrates offer a number of benefits when used in RF applications. The primary benefit is the high level of integration that LTCC based modules can provide over the standard organic based solutions. Specifically, the passive components that are used with an integrated module can be embedded into the LTCC substrate to reduce the amount of top surface area required. One application that has utilized LTCC substrates as their electrical interconnect technology is Power Amplifier modules. To ensure tight package case outline tolerances are kept, an array transfer mold may be utilized but there are a number of challenges when implementing this type of encapsulation process.

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LTCC Module Array Transfer Mold Process Improvement

Mark Gerber, Nicholas Cheng

Abstract/Introduction:

The increasing interest for smaller and more integrated wireless solutions has led companies like Motorola to investigate LTCC based module array solutions. Low Temperature Co-fired Ceramics (LTCC) substrates offer a number of benefits when used in RF applications.  The primary benefit is the high level of integration that LTCC based modules can provide over the standard organic based solutions.  Specifically, the passive components that are used with an integrated module can be embedded into the LTCC substrate to reduce the amount of top surface area required.  One application that has utilized LTCC substrates as their electrical interconnect technology is Power Amplifier modules.  To ensure tight package case outline tolerances are kept, an array transfer mold may be utilized but there are a number of challenges when implementing this type of encapsulation process.

This paper discusses one specific assembly process step that helps to enable the array transfer mold process with LTCC modules while ensuring a maximum LTCC strip utilization.   This process step addition addresses the issues associated with the high transfer mold pressure and works well with a no-LTCC contact mold tool clamping process that virtually eliminates in mold ceramic breakage.  This paper also suggest an enabling design feature on the LTCC strip that work in conjunction the mentioned process step to further eliminate the possible yield loss issue caused by the high transfer mold pressure effect.

Body:

Two alternate methods for encapsulating RF LTCC devices are using a standard glob top encapsulation method or utilizing a metal cap for RF shielding.  Each one of these solutions has both advantages and disadvantages and the disadvantages are the drivers for investigating the array transfer mold process.  The glob encapsulation process is typically a very difficult process to control the package height, especially when there are low profile requirements.  In addition, component ghosting, required substrate strip periphery keep out areas and encapsulation voiding are all considerations that must be considered for high volume production. For the metal lid solution, two main disadvantages are readily seen.  First, utilizing a metal lid requires extra substrate area, which also increases the unit package size.  The second item is final module durability. Depending on the thickness of the LTCC substrate, the rigidity of the package may prohibit handling due to substrate breakage.

The transfer mold process addresses some of the issues discussed with the previous encapsulation methods but also requires a number of other challenges that must be addressed. The method of transfer mold that Motorola has investigated includes the use of a disposable carrier to assembly the LTCC substrate strip through the backend assembly process-Die Bond through Singulation.  This carrier is typic...